Introducing Renewable Energy Small scale solar, wind and hydro-electric micro-power www.IntroducingRenewableEnergy.com
Paul Matthews
Greenstream Publishing Limited 5 Palmer House Palmer Lane Coventry CV1 1FN United Kingdom www.greenstreampublishing.com Published by Greenstream Publishing Ltd, July 2015. Copyright Š 2015 Paul Matthews. All rights reserved. ISBN 978-1-907670-50-3 Paul Matthews asserts the moral right to be identified as the author of this work. A catalogue record for this book is available from the British Library. While we have tried to ensure the accuracy of the contents of this book, the author or publishers cannot be held responsible for any errors or omissions found therein. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the publishers.
Table of Contents Introduction ............................................................................................................ 1 www.IntroducingRenewableEnergy.com........................................................... 1 About the Author ................................................................................................ 2 About the proceeds from this book ................................................................... 2 Greedy for Power .................................................................................................... 3 How to use small scale renewable energy ........................................................... 5 What is your motivation for using renewable energy? ..................................... 5 Setting expectations........................................................................................... 6 Location, Location, Location.............................................................................. 8 Harnessing the Power ........................................................................................ 9 How much power do I need? ........................................................................... 13 Making Money from Renewable Energy ............................................................. 16 How much can I earn from installing a renewable energy system? ............. 19 Getting a micro-power station for free ............................................................ 20 Energy Production and the Environment ............................................................ 21 Renewable Energy and Environmental Impact .............................................. 22 Planning Permissions and Objections ................................................................ 24 Community Concerns and Objections ............................................................. 25 Common objections to micro-power projects ................................................. 26 Building Control ................................................................................................ 32 A brief introduction to electricity ......................................................................... 33 How to measure electricity .............................................................................. 34 The relationship between volts, amps, ohms, watts and watt-hours ........... 34 Low current and high current systems ........................................................... 37 Wind Power ........................................................................................................... 38 Small Wind ........................................................................................................ 39 Simplified anatomy of a wind turbine ............................................................. 40 Inside the Nacelle............................................................................................. 41 Wind Science .................................................................................................... 42 Types of Wind Turbine ...................................................................................... 56
Mounting Options ............................................................................................. 62 What to look for when selecting a wind turbine ............................................. 69 Understanding the specification sheets ......................................................... 72 Next Steps ......................................................................................................... 76 Solar Photovoltaics .............................................................................................. 77 PV Technologies ............................................................................................... 78 Restrictions and issues with solar energy ...................................................... 79 Pricing and ongoing maintenance................................................................... 80 Connecting Up Solar ......................................................................................... 80 Surveying your site ........................................................................................... 87 How a solar panel gets its energy rating ......................................................... 91 Calculating solar energy in the real world....................................................... 91 What to look for when buying solar panels..................................................... 94 Understanding the specification sheets ......................................................... 96 Buying cheap solar panels ............................................................................... 99 Solar mounting options .................................................................................. 100 Next Steps ....................................................................................................... 104 Hydro-electric power .......................................................................................... 105 Calling in the experts ...................................................................................... 105 Anatomy of a typical small-scale hydro-electric system............................... 106 Small Hydro sizes ........................................................................................... 111 Identifying a suitable watercourse ................................................................ 112 Assessing the production capacity of your watercourse.............................. 113 Power Calculations (a rough formula) ........................................................... 121 Intake design .................................................................................................. 122 Turbine designs .............................................................................................. 126 Drive systems and gearing ............................................................................ 133 Generator options .......................................................................................... 133 Next Steps ....................................................................................................... 134 Wave and Tidal Energy ...................................................................................... 135 Wave Power .................................................................................................... 135 Tidal Power...................................................................................................... 138 Ocean Thermal Energy ................................................................................... 139
Components for a Renewable Energy system ................................................. 140 The power generator ...................................................................................... 140 How to use your energy .................................................................................. 141 Off-grid systems .............................................................................................. 141 Grid Tie systems ............................................................................................. 160 Wiring .............................................................................................................. 163 System Protection and Safety ....................................................................... 167 The complete system ..................................................................................... 169 Off-grid solar caravan (travel trailer) ................................................................. 176 Choosing your components ........................................................................... 176 Suppliers ......................................................................................................... 180 Putting everything together ........................................................................... 181 Congratulations! You’ve got a working system! ........................................... 185 Off-grid allotment wind-turbine ......................................................................... 186 Choosing your components ........................................................................... 186 Suppliers ......................................................................................................... 194 Putting everything together ........................................................................... 195 Congratulations! You have a working system! ............................................. 200 Doing it all yourself ............................................................................................ 201 DIY vs Manufactured ...................................................................................... 201 Disclaimer ....................................................................................................... 203 DIY Power Electronics .................................................................................... 204 Building your own wind turbine ..................................................................... 204 Photovoltaic Panels ........................................................................................ 208 Hydro-electric power ...................................................................................... 208 Buying second-hand batteries ....................................................................... 209 In conclusion................................................................................................... 210 Next Steps .......................................................................................................... 211
RENEWABLE ENERGY APP – SOFTWARE LICENCE KEY:
XXX XXXX This license key gives you free access to the online Renewable Energy analysis and design apps for 2015 and 2016*. Visit www.IntroducingRenewableEnergy.com to register your access code. *Usual price £49 / $69 per year.
Introduction This is a book about using renewable energy to generate electricity. It explains what renewable energy is, how it works and how you can use it to generate your own electricity with a small scale project. Renewable energy is a huge subject. This is an introductory guide to give you sufficient grounding to get you started. You will be able to evaluate your site, calculate how much energy you can generate and understand what the experts are saying. For small requirements, the book includes step-by-step instructions for two small off-grid projects: a simple solar installation and a basic wind turbine configuration, so you can put together a simple system yourself. Although I focus on small scale renewable energy systems, I also cover larger scale systems at a high level. So if you are interested in finding out about energy production in general, about larger scale wind, solar and hydro-power or wish to gain some insight into the emerging tidal and wave energy technology, you will gain an understanding of what is possible with renewable energy. I am a professional renewable energy engineer. This is the book I wish I could have read when I was starting out in this industry. It’s written for anyone who needs a basic understanding of the subject: enthusiasts, higher education students, architects, farmers and landowners, and anyone who wants their own renewable energy system and needs to know more before calling in the professionals.
www.IntroducingRenewableEnergy.com The website that accompanies this book provides useful additional resources to help you evaluate and build your own system. Along with general articles and a supplier directory, there are online calculators to assist with the following:
Identify average monthly wind speeds and direction at your location
Identify average monthly sunlight and solar energy at your location
Performance estimators for wind turbines and solar panels 1
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Hydro-electric power generation calculations
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Cable sizing calculations
These apps will help you evaluate the viability and calculate the cost of renewable power for your project. Note:
Many of these tools are professional tools that are usually only available as a paid-for subscription of ÂŁ49 ($69) per year. Full and free access for 2015 and 2016 is provided to purchasers of this book, using the software license key XXX XXXX.
About the Author Paul Matthews originally trained and worked as an electronics engineer. Deciding on a career change, he retrained as a small-scale wind turbine installer in 2006. Horrified by the poor performance, he went back to University and emerged with a degree in Energy Engineering. A spell in India followed, working on a new wind farm and hydro-power station near Bangalore. He also designed a small household solar energy system for Indian homes. Inspired by the potential for small scale renewable systems, Paul returned to the UK. He designed a solar energy system designed to provide remote African communities with electricity, worked with a team designing a hydro-electric system that could be installed on a weir and contributed to the design of a small tidal energy system that will be tested off the coast of Scotland in 2015 and 2016. Today, Paul is working on a wind project in Sweden that aims to eradicate fossil fuels for electricity production in the country by 2020. He divides his time between Sweden and his home in England where he lives with his wife and two children.
About the proceeds from this book The author royalties from this book will be donated to a new fund to design and create a low cost solar energy system for homes in third world countries. The project will create a solar power pack with sufficient lighting to light up a home, a built in radio and small appliance charging that can be built for under $10. More information on this project can be found at the back of this book. 2
Greedy for Power We have a problem in the developed world. We’re greedy for more and more power. We can never have enough. This being a book about renewable energy, I’m not referring to money, wealth or position. I’m talking about energy. We take energy for granted. Plug a hair dryer or a kettle into a socket and switch it on and it just works. Cold? Turn up the thermostat or adjust the timer on the central heating and we’re warm in minutes. We don’t have to think about the amount of energy we want to use, it is there for us whenever we want it at the flick of a switch. It’s the same with our cars. Get in, fire up the engine and you have an enormous amount of power under your right foot. Even a small family car has an engine that could produce enough power to provide electricity for one hundred houses or more. We have so much energy and we’ve taken it for granted for so long, we’ve become wasteful of the energy we have. It is only when it’s is taken away from us – such as a power cut or a petrol strike – that we discover quite how lost we are without it. We are lucky to live in a time when there is an abundance of energy. Our entire lives are shaped around it and we don’t want it to end. What has made all this possible is fossil fuel: oil, gas and coal. These fuels are amazing. They pack a huge amount of energy in a very compact form. The amount of energy in one litre of petrol (gasoline) is around the same as the energy stored in 250kg (550 pounds) of batteries. We’ve become pretty good at transporting fossil fuels around the world and we use them when we need them. As a form of usable energy, fossil fuels are pretty much unbeatable. Of course, there are problems with fossil fuels. Supply and demand, climate change, the occasional war… I’m not going to list them all here. But the issue is this: we have become addicted to oil and the benefits it gives us. We don’t want to lose those benefits. Whatever we use to replace fossil fuels, the public demands that we should be able to carry on doing the same things we currently do. And that is a big mountain to climb. Renewable energies are very good at producing smaller amounts of energy, but harnessing it on a utility scale is a huge undertaking. A single solar photovoltaic panel will produce, at most, around 300 3
watts of power: enough to watch TV, perhaps, but only a fifth of the power required to run a washing machine. Wind turbines can produce far more, but in comparison to the power output of a conventional power station, the numbers are tiny. One of the biggest issues with most sources of renewable power is that we get the power when nature dictates. Solar power relies on sunlight, wind turbines rely on wind. Even hydro-power, which is one of the more reliable and controllable sources of renewable energy, ebbs and flows with the seasons. That simply does not fit in with our demands for energy when we want it. It means that renewable energy technologies have to be supplemented with other forms of energy production. Here in the UK, a huge wind turbine building scheme now means that it is quite common for wind power to supply 20% or more of our nation’s electricity at any time. Yet on a calm day, the power output from wind turbines can be as low as 1% of our demand. The supply of this energy can fluctuate in just a few hours, making it difficult to manage supply against demand. Traditional power stations struggle to manage this fluctuation. Coal and nuclear power stations are at their most efficient when running at a constant rate. In the UK, gas-turbine power stations are being used as load-balancers, increasing production when wind energy is low and reducing it when wind energy is higher. Technology is evolving and we are resolving the issues. Tidal and wave energy, for example, has the potential to provide large quantities of reliable around-the-clock energy, whilst the development of stored solar thermal technologies in Spain demonstrates a way of providing a reliable 24-hour energy source from the sun. Right now in Sweden, I’m working on a wind farm project working with hydroelectricity to handle the peaks and troughs. It has the potential to eradicate the need for fossil fuels for electricity production in Sweden within the next four years. We are getting closer. We have the technology and the ability to generate an abundance of electricity from renewable sources. We will be able to do it cost effectively and we will be able to have energy when we want it, not when nature decides to give it to us. We don’t have all of the answers yet, but we will do. Will fossil fuels be redundant within my lifetime? Probably not. But at least we will have broken our addiction to oil and have a greener and cleaner source of energy, provided by nature, which will never run out. 4
How to use small scale renewable energy There is something quite exciting about creating your own electricity. There is always a buzz of excitement when we switch on a new wind turbine or plug in a new solar energy system for the first time. It doesn’t matter whether it is a huge project generating megawatts or gigawatts of electricity, or connecting a single solar panel to a battery and powering a lightbulb, it is a very satisfying feeling, knowing that you have created electricity out of the air. Of course it has its drawbacks: providing energy when and where nature decides to give it to us, for example, but these issues can be resolved with careful planning and the right design. This is particularly true of small scale systems where you are often producing and using electricity at the same location.
What is your motivation for using renewable energy? For some people, creating a renewable energy system is purely a practical necessity: you have a remote location, it is going to cost a fortune to get an electricity connection to it in any other way, the location makes it suitable for hydro, wind or solar, therefore micro-power is financially and logically the best solution. For others, a micro-power system is part of a bigger dream: to be self-sufficient. To Stop Paying The Man. The exciting Tiny House1 movement in the United States, now starting to gain traction in the United Kingdom too, is part of this dream. Micropower systems can be a perfect complement to a tiny house, allowing you to go completely off-grid for a comparatively small amount of money. The outdoor, camping and caravanning (caravans are called travel trailers in the United States) communities have adopted micro-power as well. If you are backpacking across the mountains, charging a torch and a phone is a great way to The ‘Tiny House’ movement that is sweeping the United States and now making inroads in the United Kingdom are typically 100-300 sq. ft. homes, often mounted on a trailer. You can find more details about tiny houses at www.TinyHouseBlog.com 1
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provide some home comforts. Likewise, adding solar power to an RV or caravan allows you to go further afield whilst keeping some of the comforts of home. Renewable energy can also be a profitable side-line or investment. If you are a farmer with wide open fields or large barns with south-facing roofs, installing a wind turbine or solar panels to sell energy to the power companies can be extremely profitable. If you own a large factory unit, installing solar panels on the roof can be a great way of reducing your own energy bills or generating electricity to sell back to the power companies. A typical payback is between four and ten years. There are a small and growing number of community projects for renewable energy as well. From installing hydro-electricity on a weir to building a community wind turbine or solar farm, communities are clubbing together to create their own renewable energy systems. In Africa, entire villages are providing themselves with electricity for the first time by coming together and building a simple solar electric power station. Their needs are often modest. Lighting for a school or community area, the ability to charge up portable devices like mobile phones or the installation of a small community refrigerator so that medicines can be safely stored at the correct temperature are often the main requirements. These systems can often be built for just a few hundred pounds or dollars, but they transform lives.
Setting expectations A lot of people like the idea of creating their own electricity, with little more than a vague appreciation of the costs, or the capability of the systems that are available. It isn’t difficult to set up a system with a small wind turbine or a couple of solar panels that can generate a kilowatt or two of electricity each day. Running an entire house off your own off-grid system is a very different proposition. The average household in the UK uses around 11½ kWh of electricity and 40½kWh of gas each day. The average household in the USA uses around 30kWh of electricity and 53½kWh of gas each day. Replacing all of this energy with your own micro-power system could be extremely expensive, particularly if this is to be your only source of energy. If your requirements are far more modest however, small scale power can be extremely affordable. Often, it can be the cheapest solution for providing a small 6
amount of power to a remote location. Here are some examples of small renewable energy systems that can be installed, along with an indication of costs:
Under one hundred pounds or dollars:
Build a solar charger for a mobile phone or other portable equipment Install solar powered lighting in a garden shed Set up an experimental wind turbine for educational purposes
A few hundred pounds or dollars:
Provide electricity for a garden shed or workshop Build a portable solar generator Install a power source for a boat, caravan, travel trailer or RV to top up a battery Build a small hydro-electric system for educational purposes Generate sufficient electricity to provide home lighting Provide a community power plant for remote communities in Africa or Asia
A few thousand pounds or dollars:
Supplement your energy use with some home-grown power Go entirely off-grid in a Tiny House, houseboat or mobile home Build a small hydro-electric system on an existing stream Create energy for your own use, selling surplus energy back to the grid
A few tens of thousands of pounds or dollars:
Go completely off-grid in an average family home Set up a small renewable energy community project Install a single wind turbine on a farm Build a small solar farm Build a small hydro-electric power station
A few hundreds of thousands of pounds or dollars:
Build a small wind farm with multiple wind turbines Build a large solar farm Build a hydro-electric power station with small reservoir 7
This book provides an overview of the options that exist. If you want to implement a system that fits into the first two categories listed above, you’ll have enough information by reading this book to install your own system. If you are planning a larger system, this book will help you identify the right solutions, but you will need to need to engage some professional help along the way.
Location, Location, Location Your choice of which renewable energy system is right for you comes down to your location. To harness wind power, you need wide open spaces. Solar energy requires direct sunlight and, preferably, a south-facing location. Hydro-electricity requires a suitable water source. If you’re lucky, you’ll have more than one of these. A farmer, for instance, may well have wide, open fields for wind power and large, south-facing barn roofs for installing solar. If you have none of these things, then your opportunity for making your own electricity is limited. You’ll be able to make a cheap and simple solar energy system for powering a lightbulb in a shed, for example, or create an experimental wind turbine to recharge a mobile phone, but you won’t be able to scale this up to make a bigger, more powerful system. For some people, that is enough. You can still experience the magic of creating your own power and doing something useful with it, even if your end system is only modest. If you don’t know your location – for example, if you want to install micro-power onto a caravan/travel trailer which you then take from place to place, you can still implement a useful renewable energy system. Solar is probably the best solution here, as you can generate reasonable amounts of power from a solar system wherever there is sunlight, even if you cannot get the best out of the location. As part of implementing a renewable energy system, you are going to need to carry out a full assessment and site survey to identify whether or not renewable energy will work in the location you have chosen. If you are planning on spending only a few hundred pounds or dollars on a system, you can do this yourself, and I will explain how in future chapters. If you are planning on spending significantly more money on a system, you can do an initial assessment yourself, but this should then be backed up by a professional assessment. 8
Harnessing the Power Generating power is only one half of the equation. Once you have the power, you need to decide how you are going to use it.
Stand-alone systems Stand-alone systems (off-grid) are the simplest forms of micro-power system. You generate the power you need, you store it in batteries and you use it when you need it. The electricity you use can either be low voltage – 12v is the most common – or you can use an inverter to run at 240v (120v in North America) to run your devices. Here is a simplified schematic that shows the different components of a simple stand-alone system for low-voltage (typically 12 volt) devices: Power Generator (solar, wind or hydro)
Battery Controller
Low Voltage Devices
Batteries
A schematic for a simple stand-alone micro-power system supplying low voltage (typically 12 volt) DC power. A stand-alone micro-power system consists of three components:
The Power Generator The power generator, such as one or more solar photovoltaic panels, or a wind or water turbine, generates electricity. This is fed into a battery controller.
The Battery Controller This is the brains of the operation. The battery controller has two tasks. It takes the energy from the power generator and uses it to charge up one or more batteries. It is also used to supply power from the batteries to any low voltage devices that are being powered by the system. 9
The task of the battery controller is to manage the battery pack: to make sure that the batteries cannot be either overcharged by the power generator or over discharged by the devices using the power.
Batteries The batteries store the energy that has been generated so that it can be used whenever it is required. Even if you are planning on using the electricity when it is produced, your stand-alone system will typically always have batteries as this allows the energy to be provided at a constant rate rather than fluctuating with supply.
Stand alone with AC power The next step up from a low voltage stand-alone system is to create a stand-alone system that incorporates an inverter to provide higher voltage AC power for running larger appliances or devices:
Power Generator (solar, wind or hydro)
Battery Controller
Batteries
High Voltage Devices
Inverter
A schematic for a simple stand-alone micro-power system supplying high voltage (either 120v or 240v) AC power. In a high voltage stand-alone system, the battery controller is responsible for handling the charging of the batteries. The inverter is responsible for taking the low voltage DC supply from the batteries and converting it to a high voltage AC supply. This can then be used to supply AC power to other devices or appliances. The inverter is also responsible of ensuring the batteries do not over discharge and will cut the power supply if the batteries run low.
Connecting to the grid Grid-tie systems allow you to take your power and either use it yourself or sell it to the power companies. Instead of storing the energy you don’t use in batteries, it is 10
absorbed into the power grid and used to supply other homes and businesses in your local area. Here is a simplified schematic for a grid-tie system where the power can either be used by you or supplied to the utility power network: Power Generator
Grid-Tie Inverter
(solar, wind or hydro)
Distribution Panel
Grid-Tie Meter Power Network
Your Premises
A simplified schematic for a grid-tie micro-power system, supplying electricity into a premises and onto the utility power network. A grid-tie micro-power system consists of four components:
The Power Generator The power generator, such as one or more solar photovoltaic panels, or a wind or water turbine, generates electricity. This is fed into a grid-tie inverter.
Grid-Tie Inverter The grid-tie inverter converts the electricity generated by the power generator into an AC supply, matching the voltage and AC frequency and wave form of the power network. This allows it to integrate with power coming from the grid. The power can then be fed into the distribution panel (sometimes referred to as a consumer unit when installed in a home) for providing power into your premises. It also links into a grid-tie meter for supplying surplus power into the grid.
Grid-Tie Meter An ordinary electricity meter measures the quantity of electricity being supplied to your premises. It is measured in kWh, sometimes referred to as ‘units’ of electricity. 11
A grid-tie meter has a minimum of two readings: a measurement of how much electricity is being supplied to your premises, and a measure of how much electricity is being provided to the grid by your micro-power system. Most grid-tie meters also have a third reading, showing the total amount of electricity produced by your micro-power system regardless of whether you use the electricity yourself or sell it back to the power companies.
Micro-Power Station If you are planning a micro-power system purely to generate electricity to sell rather than use, the schematic is similar to the previous one, minus the distribution panel if you do not require any on-site electricity whatsoever. Power Generator (solar, wind or hydro)
Grid-Tie Inverter
Grid-Tie Meter
A schematic for a micro-power station with no local power requirement. All power generated by the system is fed back into the power networks. Below: Solar Farms generating power purely for use by the power networks are becoming a common sight in the US and Europe.
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How much power do I need? If you are planning a complete stand-alone system, you need to make sure that you build a system that provides enough energy for your requirements. You also need to plan for the unexpected. What happens if you end up using more power than you anticipated? What if Mother Nature decides not to co-operate with your solar panels or wind turbine for a week or two and you’re not generating enough power? If you are planning a grid-tie system, the size of your micro-power system is not so critical: sometimes you will be producing a power surplus, and making money selling it to the power companies. Other times you will be producing less power than you need and buying in additional electricity. Either way, the switch between the two power sources is seamless. More importantly, the lights don’t go out if you are not generating enough power yourself. Moreover, if you are installing a micro-power system on your home, you may find that you are restricted as to the size of grid-tie system the power companies will allow you to connect into. For instance, in the United Kingdom, many power companies set a maximum limit of 3.8kWh – 16 amps – for the size of system they will allow. Larger systems require far more complex, and more expensive, threephase grid-tie inverters. These inverters are designed for commercial and utilityscale use and are usually too expensive to justify for a home-based installation. Your criteria is different if you are looking to become your own power supplier and sell all your electricity. The bigger your system, the more money you can make from selling electricity back to the power companies. However, it is not always as easy as that. For example, you may have a vast open field in a windy area that looks perfect for wind turbines, but because it is remote, it may not be possible to get a grid connection for more than a few kilowatts of power. If becoming your own power supplier is something that interests you, you will need to start talking to the experts and engaging with the power companies sooner rather than later.
Working out your power requirements If you are designing a stand-alone system, you will need to be fairly accurate in measuring how much energy you expect to use. One of the most common mistakes 13
is over-estimating actual energy needs and wasting a lot of the energy we consume. Most households’ waste electricity: we use inefficient appliances, leave equipment switched on and take our energy for granted. The trouble with wasting energy and over-estimating energy needs is that it makes the renewable system much larger and a lot more expensive. Few of us have money to burn, so spend some time investigating your true needs and cutting out the waste. If all you are planning to do is power a light for an hour or two in the evening, working out your needs is easy: find the wattage of the light bulb, multiply it by the number of hours you intend to use it for and you have your answer: a 20w bulb for two hours is a 40 watt-hour per day power requirement. If you are planning something more ambitious off-grid, you are going to need to spend a bit more time on your homework. You’ll need to find out the power demand for everything you wish to use, expressed in watts, and multiply it by the number of hours you use it each day. The most accurate way to do this is to buy a plug-in watt meter. You plug it into the domestic power socket, then plug your device into the watt meter. The watt meter then displays the current draw for the device and will record over time the watt-hours of electricity used. Alternatively, you will find that most electrical appliances around the home will show their power requirement on a small label on the back of each unit, either in watts or in amps. If the figure is in amps, multiply this by the voltage in order to find out the wattage. It’s not as accurate as using a watt-meter, but is a useful way of finding out roughly how much power each of your devices needs. If you are planning a grid-tie system, such as powering a house, you do not need to be so accurate with measuring your power requirements. In this case, using a smart meter is a better solution. Now being installed as standard in many homes and available to buy very cheaply, a smart meter measures the electrical current being used by your property in order to show your instant demand and your watthour requirement over a period of time. You can also carry out meter readings every day in order to find out how many kilowatt-hours of electricity you have used on a day-by-day basis. Finally, because your demand for electricity will vary at different times of the year, you can look at your old electricity bills and find out how many units of electricity you have used each month for the preceding year. 14
When people start measuring the amount of electricity they use, they are often shocked how much energy is just wasted. TVs, set top boxes and computers on standby (although brand new TVs are far better than they were three or four years ago) all consume electricity, and as anyone with teenagers will know, TVs, lights and computers are all left on even when they are not being used. Most houses also have a hidden power drain as well. Central heating boilers, timers and pumps all consume electricity, even if the heating itself comes from gas, oil or biofuel. If you are planning an off-grid system, split out your requirements so that heating, hot water and cooking are separate from the rest of your list. Using electricity to generate heat is expensive because you need a lot of energy to create this heat. If you are reliant on electricity for any of these purposes you are going to end up with a very expensive system. Consider, where possible, other alternatives for your heating, hot water and cooking needs such as biomass, solar hot water or gas. Likewise for air conditioning. If you are planning to live off-grid in a hot climate, air conditioning uses a huge amount of energy. It is possible to buy an off-grid solar air conditioning system, but these are not cheap and are best suited to very small buildings. You may also wish to consider other forms of air cooling, such as ceiling fans, passive solar design, ground source heat transfer and whole-house ventilation. There is a big difference between living off-grid, where you are entirely reliant on your power system throughout the year, and holidaying off-grid, where you only use your system for part of the year or for a few days each week. Inconveniences such as running out of power because you’ve miscalculated how much energy you need may be acceptable on holiday. If you are reliant on your system to live, such problems can rapidly become major issues. Consequently, off-gridders will need to make sure they work out their power requirements accurately and then add a healthy contingency. You will also need to plan a contingency system, such as a small generator, that can take over in an emergency. Once you know how much energy you need per day, then you can start to work out what you will need to make your micro-power project a reality.
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Making Money from Renewable Energy Creating your own environmentally friendly energy is not only good for the environment. It can be potentially be good for your bank account too, but only if you are going the grid-tied route. You can make money in various ways from running your own micro-power station:
Feed In Tariffs Feed In Tariffs (often referred to as FITs) are the most common way to make money from your micro-power system. A feed in tariff is the price you are paid by the power companies for every kilowatt-hour of electricity you supply them with. In many countries, the amount of money you get paid is a fixed amount per kWh supplied, with a guaranteed rate for many years to come. This means that you have a clear idea at the start of the contract how much you are going to be paid, safe in the knowledge that the rate will not be cut a few months or years later. In some countries, including the United Kingdom, the feed in tariff is more generous and provides an additional payment for every kilowatt-hour of electricity that you generate, regardless of whether you use that electricity yourself or supply it to the power companies. Consequently, these feed in tariffs usually ensure a payback on investment of between three and twelve years. The three year period may be optimistic for most installations, but some wind turbine operators report a payback period of four to five years in good locations, whilst home owners with a solar installation usually recoup their investment in seven to ten years. Feed in tariffs are available in most countries, although the details do vary from one country to the next. In the United States of America, feed in tariff rates and conditions are set at State level. In the United Kingdom, the scheme is countrywide. Whilst the following explanation of the British system is specific to the United Kingdom, it is worth reading it if you live elsewhere as it will give you a good idea of how most feed in tariffs work in other countries, even if the specifics may be different. 16
Feed in tariffs in the United Kingdom In the United Kingdom, the rates you earn from a feed in tariff varies depending on the size of the system (smaller systems get a higher rate per kWh, in order to encourage householders), what technology you install (solar, wind or hydro) and when your system was installed (early adopters received a much higher amount in order to stimulate demand). There are two elements to the British feed in tariff: 

The generation tariff pays you for every kilowatt-hour of electricity that you generate, regardless of whether you use this electricity or sell it to the power companies. The export tariff pays you for every kilowatt-hour of electricity that you sell to the power companies.
Under this scheme, you can sell up to half of the energy that you generate. You receive payments from your normal electricity supplier. In order to qualify for feed in tariffs, your system must be installed using components and by an installer certified by the UK-based Microgeneration Certification Scheme (MCS). The Microgeneration Certification Scheme is an internationally accepted quality assurance scheme that certifies microgeneration products and installers. For the most up-to-date information on feed in tariffs in the United Kingdom, visit https://www.gov.uk/feed-in-tariffs. Feed In Tariffs allow home owners, business owners and farmers to earn money by installing their own Renewable Energy systems on their property.
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Installation Grants Before feed in tariffs became established around six years ago, there used to be various grant schemes for installing micro-power systems. Some of these covered stand-alone systems as well as grid-tie. In the main, most of these have now disappeared and been replaced with feed in tariffs. However, there are instances where grants for installing micro-power systems are available and it is always worth doing a search on Google to see whether there are any schemes that are available for you. For instance, at the time of writing (May 2015), there are rebates for solar energy systems in various counties in California, covering residential, commercial, agricultural, governmental and non-profit buildings. There are also state-wide rebates available for solar installations for low-income families and for multi-family affordable housing2. In the United Kingdom, the Rural Development Programme currently has a fund to help farmers, land owners and community-based cooperatives pay for the up-front costs of developing their own renewable energy systems. The fund incorporates a grant of up to ÂŁ20,000 for testing the viability of a micro-power system, followed by a low-interest unsecured loan to fund up to 50% of the installation costs of a renewable energy project3.
Renewable Obligation Certificates Renewable Obligation Certificates (ROCs) are specific to the United Kingdom and are designed for larger generators, producing 50kW or more of power. They are in the process of being phased out and replaced by the feed in tariff scheme, but remain open for new generators until 2017. In order to encourage the wide scale production of renewable energy, the British government introduced an obligation for electricity suppliers to source a The California Solar Incentive (CSI) is overseen by the California Public Utilities Commission. You can find more information on their website at http://www.cpuc.ca.gov/PUC/energy/Solar 2
The Rural Community Energy Fund is jointly funded by DEFRA and DECC. For more information, visit http://www.wrap.org.uk/content/rural-community-energy-fund 3
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percentage of their power from green sources in 2002. Initially set at 3%, this percentage has gradually increased year-on-year. For 2015/2016, electricity suppliers must source 15.4% of their electricity from renewable sources. To enforce this, the government introduced the Renewable Obligation Certificate. If you generate green energy, you receive these certificates for each megawatt (MW) of electricity that you generate. You then sell these ROCs to the electricity suppliers on the open market, who present them to Ofgem (the Office of Gas and Electricity Markets) to prove they have reached their obligation. If the power companies cannot supply sufficient ROCs, they are fined. ROCs effectively guarantees that there is a market for the electricity that you generate, with the ROC element ensuring that you receive a premium over more traditional power generation methods. At time of writing, a ROC is trading for £43 on the open market. As a larger power supplier, you would also negotiate a specific contract with a power supplier for the sale of your electricity. These Power Purchase Agreements (PPA) usually offer either a fixed price for your electricity production, or a two-tier price based on the time of day your system is generating power. Payments are either made monthly or quarterly.
How much can I earn from installing a renewable energy system? It is really difficult to provide specific information, because it depends on so many different factors and you will need to do a full survey of your site, consider the different options and investigate the latest feed in tariff information for your area in order to get a reasonable idea of what income you could generate. However, here are some figures based on the United Kingdom feed-in tariffs:
A 4kW domestic roof-top solar installation on a south-facing roof in central England could generate an income of around £470 per year on the generation tariff. Depending on how much electricity you use yourself, you could earn a further £50-100 by selling your surplus electricity. You would 19
also save a similar amount on your existing electricity bills by using your own power. A 15kW wind turbine on a farm in central England could generate around 28,600kWh of electricity per year, providing an income of £4,632 on the generation tariff, and a further £1,375 of electricity, which could either be exported or used by the farm. A 50kWp solar farm in central England could generate around 40MWh per year, providing an income of around £6,400 per year from the generation tariff and around £1,920 each year from the sale of electricity. A 50kW wind turbine on a farm in central England could generate around 63MWh per year, providing an annual income of around £9,135 from the generation tariff, and a further £3,025 each year from the sale of electricity.
Getting a micro-power station for free Free micro-power? It is possible. If you want to install a grid-tie micro power station but do not have the capital to do it, there are companies around that can install a system with no up-front costs. In effect, what they are actually doing is funding the system through the feed in tariff schemes. You are renting them roof space, or a space in a field, in order to erect solar panels or a wind turbine, and have use of the green electricity that is generated. Depending on the deal, you might expect to get some or all of the generated power for free, or you may need to pay for it at a reduced rate. Either way, it can be a good way to ensure that you are using green power without having a big up-front cost. The schemes vary from one region to another, so check carefully to see what is available in your area and shop around. There are free schemes for solar power across the United States, Canada, the United Kingdom and Australia, amongst others.
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Energy Production and the Environment For the past one hundred years, the vast majority of our energy has come from fossil fuels. Whether we are burning it in our cars, heating our homes or using it to generate electricity, fossil fuels are providing us with a way of life that would have been unimaginable to our ancestors. Of course, this energy comes at a cost. Air pollution in our cities is now regarded as an urgent public health issue, responsible for around 60,000 deaths per year in the UK. Greenhouse gases are changing the global climate, increasing the mean surface temperature of the planet and creating extreme weather systems, creating more powerful flooding, drought and tornadoes than ever previously recorded. Once, nuclear energy was regarded as the answer. Back in the late 1940s and 1950s, this wonderful new fuel was predicted to provide so much electricity, at such low cost that it would be too cheap to meter and would provide us with all the heat, light and energy that we could possibly ever need. The 1945 book The Atomic Age predicted that fossil fuels would go unused, with nuclear power being used for powering everything from cars to powering artificial hearts. What, asked the proponents, could possibly go wrong? Of course, today we know what is wrong with nuclear power and despite the promises of nuclear fusion, the dreams of a safe, nuclear powered future are no closer to being achieved than they were in the 1940s. If we are going to move away from fossil fuels, what are we going to replace them with? As mentioned in the earlier chapter Greedy for Power, renewable energy provides us with electricity when Mother Nature decides to give it to us, rather than when we want to use it. That gives us a problem: there is no correlation between supply and demand. Demand for electricity varies throughout the day. In hot climates, demand for electricity increases rapidly after 9am and peaks in the early afternoon, due to the demands for air conditioning, then falls away in the early evening. In cold climates, demand for electricity rises steadily throughout the day, peaks in the early evening and then falls away by around 11pm. 21
A logical fit for hotter climates is solar, particularly because demand for air conditioning is at its peak on sunny days, when solar is also generating peak power. For other climates, however, finding a perfect power source is not so clear cut. The answer is to develop a mix of power sources and to spread them around. Solar, wind, hydro, tidal and wave power all have a part to play. Combining these sources allows us to balance out our power generation capabilities. Hydro-electricity can be one of the most controllable renewable energy sources within this mix, particularly if the water source is a reservoir. Power production can then be increased and decreased according to demand, quite literally at the twist of a tap. Hydro-electricity also provides us with the ability to store huge quantities of energy and release it at a later time when it is required. Called Pumped Storage Hydroelectricity (PSH), it works by having two water reservoirs at different elevations. When demand for electricity is low, water is pumped from the lower reservoir to the higher reservoir. When demand is high, water is then released from the higher reservoir, through the hydro-electric turbines to the lower reservoir, generating electricity to handle the higher demand. Although the net result is less efficiency, the ability to store electricity in this way is a significant advantage: if it is windy in the middle of the night, for example, wind turbines can generate more electricity than there is demand for. By storing the energy in a pumped storage system, the energy can be stored for release later in the day when it is needed.
Renewable Energy and Environmental Impact It is a simple fact that if we want to generate energy, there is going to be an impact on the environment. No form of electricity production is going to be entirely green. In terms of carbon footprint savings, renewable energy systems have an obvious advantage over traditional forms of power production. There is no pollution at the point of use. It is not true, however, to say that the electricity produced is entirely carbon free: the carbon impact is in the production and transportation of the power generation equipment, the installation and maintenance of the system and the decommissioning of the system at the end of its life. Compared to the carbon footprint of a traditional power station, these figures are very low. A typical wind turbine, for instance, is rated at 11g CO2e per kilowatt-hour 22
of electricity produced, compared to 977g CO2e per kilowatt-hour for a coal-fired power station. Similarly, solar photovoltaic panels are rated at 44g CO2e for every kilowatt-hour of electricity produced over the lifetime of the panel. There are other environmental factors to consider, too. Whilst fitting a handful of solar panels onto a roof of a house is unlikely to be a problem, a field of solar panels in a solar farm may cause problems of reflective dazzle that could affect nearby airfields. Installing solar panels on a vertical wall can also cause problems with dazzle that can affect the immediate surroundings. Wind turbines can cause more serious problems. The latest designs are much quieter than previous models, but noise levels do increase as wind speeds increase, and the constant noise can create disturbance. Again, this is unlikely to be a problem if you are just installing one small wind turbine, but if you are planning to install one or more larger turbines, there is an issue: according to a recent US study in Maine, the constant noise from the rotating blades of multiple industrial wind turbines disrupts sleep patterns and can cause stress-related conditions, including depression, anxiety and more severe mental health problems. Living or working in the shadow of a wind turbine can also cause problems. The constant flashing shade of a turbine over a prolonged period can cause headaches and migraines and trigger epileptic fits in sufferers. In the very early days of wind turbines, the reflection of the sun on rotating blades also caused issues. Today, turbines and blades are coated with a non-reflective paint finish to resolve these particular problems. Hydro-electric power generation also has an environmental impact, particularly with regards to nature conservation and the water flow. A hydro installation needs to curtail the impact on wildlife, in particular swimming birds and fish. In some countries, you will require additional licenses to install hydro-electric power as it is regarded in law that water running through a premises in a stream or river is not owned by the landowner. For micro-power generators, if you design and site your system properly, you are unlikely to run into any significant problems. However, the design process does need to take the environmental impact of your project into account, particularly if you require planning permission in order to install your micro-power system. 23
Planning Permissions and Objections Rules and regulations about installing micro-power generation vary tremendously around the world. In very general terms, however:
If you want to install a single solar panel or portable wind turbine onto a temporary building such as a garden shed, you almost certainly do not need planning permission to do so. Likewise, if you want to install a solar panel or portable wind turbine onto a caravan or RV, you will not need permission to do so. However, you will need to ensure that your installation does not compromise the safety of your vehicle or do anything that would cause your vehicle to fall foul of construction and use regulations. If you want to install a small roof-top solar (up to 4kWp capacity) onto a residential, commercial or agricultural building, you are unlikely to need planning permission, but will need to ensure that installation work is carried out in line with building regulations, where these exist. Speak with your local planning office to find out what they say about permissions and regulations. For any other installation, you are likely to require planning permission. If you are planning a hydro-electric installation, there are additional permits and licenses. In the United States, water rights are held by individual states and you will need to get in touch with your county engineer. You will also need to contact the Federal Energy Regulatory Commission and the US Army Corps of Engineers. In the United Kingdom, you will need a water extraction license from the Environment Agency.
In the main, planning departments look on applications for small scale renewable energy projects positively. Many of them have their own renewable energy experts working within the planning departments, who can be a great source of free advice, guidance and support. Involve them at an early stage with your project and you will usually find them extremely helpful, pointing out potential issues and suggesting solutions to you and supporting you through the necessary paperwork.
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If you need to go through a planning application, you may be asked to provide an environmental assessment of your project. This may be requested where your project creates an impact on the landscape and visual amenity, where nature conservation is at risk or where water courses are disturbed. For most micro-power projects, such an environmental assessment is fairly straightforward. If you are planning a bigger system, usually defined as a system with a power generation capacity of over 100kW, then you are likely to have to go into much more detail. In the United Kingdom, you may be asked to do a full formal survey and provide an Environmental Impact Assessment (EIA). From a planning perspective, the biggest issue with wind turbines is siting them, particularly if you are close to a residential area. In the United Kingdom, planning guidance allows a night-time noise level from wind turbines of 42 decibels. This is about the same amount of noise as a hum from a refrigerator or a central heating system. Modern wind turbines are very quiet, but in extreme weather, noise levels can increase. In practical terms, this means that your wind turbine should be at least 380 yards (around 350 metres) from the nearest human habitation, and preferably closer to 550 yards (500 metres). Larger, utility scale wind turbines capable of 500kW or more will need to be significantly further away than this. In the United States, renewable energy systems are classified as residential or small scale systems if they have a rated output below 100kW. Midsized systems are rated as 100kW to 1MW and utility-scale is 1MW plus. Planning regulations for small scale are much easier and simpler than midsized systems and utility scale systems, with virtually all planning being handled at local level. In many cases, the permits required to install a small scale system are handled administratively via the building or zoning permit application process and only take a few days to approve.
Community Concerns and Objections If your micro-power generation project is very small, you are unlikely to have any problems with nearby residents. However, wind turbine and hydro-electric power projects are more emotive and can cause problems with installing a micro-power system. 25
If you are a farmer planning to install a 20-50kW wind turbine on your land, you can reasonably justify this on the grounds that you will use most of the electricity you produce on the farm itself. This is particularly true if you own a dairy or poultry farm, as your electricity usage will already be considerable. Once you go beyond 50kW sized wind turbines, it can be harder to justify your turbine purely on these grounds, and the size of the turbines become considerable. At this point, you run the risk of your project becoming the focus of more determined opposition.
Common objections to micro-power projects Noise This is usually only a concern with wind turbines. We have already touched on this subject, and it is true that older models of wind turbine are noisy. Designs have vastly improved over the past ten years and continue to improve all the time. Today it is quite possible to stand underneath a modern wind turbine and hold a conversation without raising your voice. The noise from a wind turbine comes from three different sources:   
The motion of the rotor blades as they cut through the air, The gearboxes inside the wind turbine that convert the low speed of the blades to high speed for the generator, Long wave propagation: a low resonance sound that is often undetectable to the human ear and entirely inaudible when standing next to a wind turbine, but that can resonate when it comes into contact with buildings some distance away.
All three of these noises have been reduced with the latest designs of wind turbine. Rotor blades have been reprofiled to reduce noise, whilst gearboxes are now far more efficient than before, or have been eliminated completely with new generator designs that can generate electricity from the turbine without a gearbox whatsoever. Many older designs of wind turbines actually amplified the gearbox noise through the steel casing for the turbine and the tower it was mounted on. Modern designs 26
have rectified this problem and now absorb much of the internal noise from the gearbox rather than amplifying it. Long wave propagation is mainly a problem with the much bigger wind turbines and is not normally experienced with the smaller wind turbines discussed in this book. The industry is resolving this problem using noise cancellation technologies. Another way to resolve the problem with long wave propagation is to plant a row of semi-mature trees and bushes between the wind turbines and nearby buildings. This breaks up the sound waves so they do not cause the resonation in the first place. Take care, however, that the trees are far enough away from the wind turbine so that it does not affect the performance of the system.
Aesthetics I am always a little bemused by people complaining about a wind turbine being ugly. I presume they are comparing it to the elegance, majesty and beauty of a coalfired power station? Personally, I find wind turbines elegant and graceful, but I can appreciate that they do have an impact on the landscape and that areas of outstanding natural beauty are not enhanced by installing fifty or sixty wind turbines on it. People love the countryside, and plonking a wind turbine in the middle of a pastoral scene isn’t going to go unnoticed! A 50kW wind turbine has a 29 foot length blade (9 metres) and stands on a tower that is either 80 foot (24 metres) or 120 foot (36.5 metres) tall. That is not too bad, but scale that up to a 500kW system and the blades are around 90 feet in length (28 metres), standing on a tower that can be up to 300 feet (90 metres) tall! Like it or not, if you are going to install a large wind turbine, or if you are proposing a wind farm with half a dozen wind turbines, you are going to get objections because of the aesthetics. You can reduce the visual impact with aesthetics: instead of bright white, many wind turbines are now available in grey, which reduces the contrast between the wind turbine and the sky. Towers do not need to be white, either. You can have a tower with the lower section painted dark green or brown and the upper section in blue or grey in order to help the tower blend in better. Aesthetics also matter for hydro-power as well. Micro-power in hydro-electric terms relates to systems of up to 100kW peak output, which can be quite sizeable. As 27
many streams and rivers are picturesque, how well the system blends into the landscape may be an important factor.
Not In My Back Yard! If people decide they don’t want a wind turbine, hydro-power or a solar farm in their vicinity, you often end up with lots of entirely inaccurate claims being made in order to discredit your plans. Some people have even had objections for even small 4– 6kW wind turbines that are creating electricity for their own smallholding or rural business. In my experience, people who start coming up with these claims do have some legitimate concerns and worries about your project, but instead of saying what they are, they make general objections to wind turbines, gleaned from the internet, which are often inaccurate or entirely irrelevant to your project, The majority of concerns are related to wind turbine projects. If you are only erecting a wind turbine to provide sufficient power for a household or for a small farm, telling people that this is the case is usually enough to persuade people that your plans have merit. To the uninitiated, even a low power wind turbine looks large and people may fear that you are going to destroy their landscape with dozens of huge wind turbines. If you are planning on installing a large wind turbine, or a series of wind turbines, then you are going to have a lengthy planning process, and you may get a lot of resistance from local people. If, on the other hand, you are constructing one wind turbine for your own power production, you are unlikely to have significant problems with planning, so long as your wind turbine is suitably sited, and if you are prepared to make a few some concessions along the way to reduce legitimate concerns from local residents. Having answers ready for the nay-sayers and then moving on to ask questions about their specific concerns and finding ways to accommodate them is constructive. Don’t focus on the negatives. Instead, highlight the benefits of locally produced, green electricity and find ways of resolving any legitimate concerns. Here are a few of the comments and concerns you may come across:
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“They don’t make enough energy to make it worthwhile” It depends what you mean by worthwhile. As a micro-generator, you’re not trying to change the whole world. A 20 – 50kW wind turbine produces enough electricity to provide all the power for a farm, with some to spare. With the current desire from many people to buy local produce, surely it makes sense for the farmers to harvest the wind to produce local energy as well?
“They are financed by our taxes. Why should we pay?” True, subsidies are available, but not necessarily from taxes. Yet nuclear, oil, gas and coal fired power stations are regularly bankrolled by taxes. For example when a new power station is built, it is often with government backed loans and grants that can easily run into hundreds of millions in tax-payers money. In the case of most renewable energy projects, there are usually no up-front grants or loans. Instead, you are paid by power companies for the energy you produce through a feed in tariff. You also earn renewable energy credits (in the United Kingdom) which can be sold to energy providers who are not producing sufficient green energy of their own. This money is paid by the power companies themselves, which means there is little or no subsidies being paid for through government funding.
“They won’t reduce carbon emissions” A few years ago, there was genuine concern that wind turbines simply would not have an impact on improving grid-wide carbon emissions. This was a concern that a number of colleagues and I had personally and it took a lot of calculations and real world testing to prove that wind turbines do improve carbon emissions. The concern was simple: because wind turbines can be intermittent in their power generation, gas-fired power stations would be running less efficiently as they continuously had to ramp up and drop down power generation in order to handle the fluctuations. The argument was that running gas-fired power stations in this way was so inefficient we would end up burning as much, if not more gas and releasing more CO2 than by not having the wind turbines in the first place. However, analysis of power production in the United Kingdom since 2011 has demonstrated that this is not the case. Improved wind forecasting over the past few years allows the National Grid to plan the right mix of energy production a day in advance with high levels of accuracy. Gas-fired power stations have been 29
demonstrated to maintain their levels of efficiency over a wide power generation band. When we have a windy day, the gas usage at gas-fired power stations drops as wind turbines take up more of the power generation. Wind turbines truly are delivering the carbon benefits claimed of them. With hydro-electricity, the more constant production from your watercourse means that the electricity supply is more reliable. There is no doubt that a good hydroelectric system can have a significant carbon benefit.
“If we allow one, in ten years’ time there will be hundreds of them” I have a bit of sympathy for this view. There are lots of examples where the countryside has become inundated with clusters of wind turbines or huge solar farms. Although it is great to see wind and solar power replacing dirtier sources of power production, the planning authorities do have a responsibility to ensure that wind turbines do not overpower an area. If you are only planning one or two turbines, or a small amount of solar, you may be able to allay fears by saying that you will not increase the number of turbines or solar panels on your land. Making a covenant to this effect may help put minds at ease.
“Wind turbines kill hundreds of birds” Much has been made about wind turbines killing birds who are struck by the blades. Each year, around 55 million birds are killed by cats in the United Kingdom, 10 million are killed by traffic, around 30 million are killed by flying into buildings and an estimated 400,000 are killed by flying into power lines. In comparison, between four and six birds or bats are killed each year by a single utility-scale wind turbine, reducing to an average of one bird death per year on a 20–50kW turbine.
“Hydro-electricity damages water courses” If you are planning a hydro-electric power station, you may be asked to do an environmental survey to ensure that you are building your system in an environmentally responsible way. In the United States, water rights are controlled at state level and you will need to speak with your county engineer in order to arrange a permit. In addition, you will need to inform both the Federal Energy Regulatory Commission and the U.S. Army Corps of Engineers. 30
In the United Kingdom, you need to apply to the Environmental Agency for a water extraction license before you are allowed to install hydro-electricity. The agency are likely to refuse you unless you have carried out an assessment and built in mitigation for any issues. However, the agency are also extremely helpful, pointing out potential hazards and issues and often suggesting ways of overcoming these issues, so if you are planning a hydro-electric system it is worth getting the environmental agency involved at an early stage. Many environmentalists and anglers are wary of hydro-electric power, even on a small scale. For hydro-electric power to work, you must have water flowing down. Many small systems are installed on weirs where a head of water then drops down rapidly into a lower pool (called a weir pool) before continuing down the river. The concerns focus around two main areas: Biodiversity Weir pools encourage biodiversity because of the water plunging over the weir. This encourages a wider range of habitats, including spawning grounds, which in turn encourages a greater variety of fish into a river. However, the water pressure from a weir scours the river bed clean immediately after the weir itself. The good habitats within the river are further along the weir pool where the water has slowed down. There is speculation that a small hydropower station on a weir could actually improve the quality of biodiversity within a weir pool because the pressure of water is reduced, thereby reducing the scouring effect. Fish Passage Some species migrate up and down stream whilst others do not go far. Going downstream is no problem: depending on the type of hydro-power system you go, the fish will either travel through the hydro turbine safely or there needs to be a separate route so that the fish can travel past the hydro turbine. To go upstream, fish need a fish pass. Fish passes are often found on rivers, at weirs and locks and are now mandatory for new hydro schemes in Europe (and, I believe, in the United States). A fish pass is a channel that bypasses the turbine, routed so that the outflow is next to the screws so that the fish can find it. 31
Older fish passes were made of concrete with little or no thought to aesthetics. Newer designs often look like natural streams, with pebble bottoms and are quite often used by some species of fish as spawning grounds. In many cases, a careful hydro-electric system design can improve migration for fish, encouraging additional biodiversity in an existing watercourse. This is particularly true if you are using an existing weir where there is no existing fish pass in place, as you will be required to construct one as part of your new system.
Building Control Known as Building Regulations in the United Kingdom and Building Codes in the United States, building controls are a set of rules that specify the minimum standards for construction. It is a legal requirement that any construction that falls within the remit of the building codes is built to the standards specified. Rules and regulations vary around the world, but in the main, you are going to need to follow building controls for your own micro-power project. The only exceptions to this are likely to be small off-grid installations that are either entirely stand-alone or a small off-grid installation fitted to a temporary structure such as a shed, caravan or recreational vehicle. The building controls that you are specifically likely to encounter on a micro-power project include:
If you are installing solar onto a roof, you will need to carry out a structural survey to ensure the roof is strong enough to take the weight of the panels and ensure the panels are installed correctly. If you require additional building work, such as building or modifying a dam for a hydro-electric system or building foundations for a wind turbine, you will need to conform to relevant building regulations. Cable routing and protection. Connecting the high voltage electrics and connecting your system to the grid.
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A brief introduction to electricity If you have not looked at electrics since learning physics at school, you may be a little rusty on terms like voltage, current, resistance, power and energy. This chapter is designed to be a little reminder for people who can wire a plug, but who start to struggle when trying to work out amps and watts. This chapter has been adapted from Solar Electricity Handbook, written by Michael Boxwell and also published by Greenstream Publishing. It has been reproduced with permission of the author. When you think of electricity, what do you think of? Do you think of a battery that is storing electricity? Do you think of giant overhead pylons transporting electricity? Do you think of power stations that are generating electricity? Or do you think of a device like a kettle or television set or electric motor that is consuming electricity? The word electricity actually covers a number of different physical effects, all of which are related but distinct from each other. These effects are electric charge, electric current, electric potential and electromagnetism:
An electric charge is a build-up of electrical energy. It is measured in coulombs. In nature, you can witness an electric charge in static electricity or in a lightning strike. A battery stores an electric charge An electric current is the flow of an electric charge, such as the flow of electricity through a cable. It is measured in amps An electric potential refers to the potential difference in electrical energy between two points, such as between the positive tip and the negative tip of a battery. It is measured in volts. The greater the electric potential (volts), the greater capacity for work the electricity has Electromagnetism is the relationship between electricity and magnetism, which enables electrical energy to be generated from mechanical energy (such as in a generator) and enables mechanical energy to be generated from electrical energy (such as in an electric motor)
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How to measure electricity Voltage refers to the potential difference between two points. A good example of this is an AA battery: the voltage is the difference between the positive tip and the negative end of the battery. Voltage is measured in volts and has the symbol ‘V’. Current is the flow of electrons in a circuit. Current is measured in amps (A) and has the symbol ‘I’. If you check a power supply, it will typically show the current on the supply itself. Resistance is the opposition to an electrical current in the material the current is flowing through. Resistance is measured in ohms and has the symbol ‘R’. Power measures the rate of energy conversion. It is measured in watts (W) and has the symbol ‘P’. You will see watts advertised when buying a kettle or vacuum cleaner: the higher the wattage, the more power the device consumes and the faster (hopefully) it does its job. Energy refers to the capacity for work: power multiplied by time. Energy has the symbol ‘E’. Energy is usually measured in joules (a joule equals one watt-second), but electrical energy is usually shown as watt-hours (Wh), or kilowatt-hours (kWh), where 1 kWh = 1,000 Wh.
The relationship between volts, amps, ohms, watts and watt-hours Volts Current x Resistance = Volts IxR=V Voltage is equal to current multiplied by resistance. This calculation is known as Ohm’s Law. As with power calculations, you can express this calculation in different ways. If you know volts and current, you can calculate resistance. If you know volts and resistance, you can calculate current:
Volts ÷ Resistance = Current 34
V÷R=I Volts ÷ Current = Resistance V÷I=R
Power Volts x Current = Power VxI=P Power is measured in watts. It equals volts times current. A 12-volt circuit with a 4amp current equals 48 watts of power (12 x 4 = 48). Based on this calculation, we can also work out voltage if we know power and current, and current if we know voltage and power:
Power ÷ Current = Volts P÷I=V Example: A 48-watt motor with a 4-amp current is running at 12 volts.
48 watts ÷ 4 amps = 12 volts Current = Power ÷ Volts I=P÷V Example: a 48-watt motor with a 12-volt supply requires a 4-amp current. 48 watts ÷ 12 volts = 4 amps Power (watts) is also equal to the square of the current multiplied by the resistance:
Current² x Resistance = Power I² x R = P 35
Energy Energy is a measurement of power over a period of time. It shows how much power is used, or generated, by a device, typically over a period of an hour. In electrical systems, it is measured in watt-hours (Wh) and kilowatt-hours (kWh). A device that uses 50 watts of power, has an energy demand of 50Wh per hour. A solar panel that can generate 50 watts of power per hour, has an energy creation potential of 50Wh per hour. However, because solar energy generation is so variable, based on temperature, weather conditions, the time of day and so on, a new figure is now often shown specifically for solar systems: a watt-peak (Wp) rating, sometimes shown on a specification sheet as a Pmax rating. A watt-peak rating shows how much power can be generated by a solar panel at its peak rating. It has been introduced to highlight the fact that the amount of energy a solar panel can generate is variable and to remind consumers that a solar panel rated at 50 watts is not going to be producing 50 watt-hours of energy every single hour of every single day.
Direct Current and Alternating Current There are two different types of current that can flow through an electrical circuit. Direct Current is a constant charge flowing in one direction, moving from the high voltage (positive) power source to the low voltage (negative) power source. Batteries and solar panels both work on direct currents. An alternating current is a stream of charges that reverse direction very rapidly. The current switches directions several times each second. This cycle of switching directions is called frequency and is measured in Hertz (Hz). The faster this cycle of switching, the higher the frequency. AC power in Europe cycles around 50 times a second (50 Hz), whilst in the United States, AC power cycles 60 times a second (60 Hz). Grid electricity works on AC power. The vast majority of wind turbines and hydroelectric systems also create AC power.
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Low current and high current systems When we are designing systems, we generally want to keep the currents as low as possible. The reason for this is simple: if we try and put too much current through a circuit, the resistance to this current increases exponentially. This resistance creates heat and reduces the overall efficiency of the system. This resistance builds up over distance, which means that the higher the current, the more issues you will have with power loss, particularly over a long cable runs. To overcome the resistance, you either need to install thicker and heavier cables to overcome the resistance, or increase the voltage of the system. If you double the voltage of a system, you halve the current and therefore reduce resistance significantly. For example, let us say that we have two 12v, 200Wp solar panels that we wish to connect together to charge a battery. We have the choice of connecting them together in a series, to create a 24v, 200 watt circuit, or connect them in parallel in order to create a 12v, 200 watt circuit:
A 12 volt 100Wp solar panel has a current flow of 8.3 amps (100 watts ÷ 12 volts = 8.3 amps). If we connect the two solar panels up in series, the solar array also has a current flow of 8.3 amps (200 watts ÷ 24 volts = 8.3 amps). If we connect the two solar panels up in parallel, the solar array has a current flow of 16.6 amps (200 watts ÷ 12 volts = 16.6 amps).
By and large, it is better to double the voltage rather than double the current. Of course, there are exceptions to this rule: if, for instance, you want to use your system at 12 volts, for example, then you may decide to use thicker cables and keep cable distances to a minimum. This does limit the overall size of your system, but this may not matter. So long as you are aware of the problems and design around them, there is nothing wrong with this approach.
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Wind Power The wind is the oldest source of power harnessed by mankind. Sailing ships have been in use for at least 7,500 years whilst the first ever windmill to power a corn mill was built in Greece during the first century AD. Throughout the middle ages, windmills were used for grinding corn into flour and pumping water for irrigation. Later on, they began to be used for sawing timber and for grinding spices, tobacco, dyes and cocoa. In the latter half of the 19th Century, water pumping windmills became popular in the United States, allowing vast tracts of otherwise inhospitable land to be farmed. Around six million water-pumping windmills were built in the United States between 1850 and 1950. Harnessing the power of the wind is an important part of mankind’s history. With the creation of wind turbines for electricity generation, it is as relevant and important today as it has always been. Wind is one of the most promising sources of renewable energy sources for electricity production, particularly in colder climates where electricity demand is higher in the seasons when wind energy is at its peak. Wind power has a number of benefits for electricity production: it’s environmentally friendly, with the carbon footprint associated with the production, assembly and installation of the wind turbine usually recovered within a few months of production; they can be installed quickly and additional turbines can be added to a wind farm quickly if demand rises. Wind turbines are extremely reliable, requiring minimal maintenance and servicing. Of course, there are disadvantages as well. The wind blows when it wants to, not when we want it, which means that matching supply with demand is more difficult. From a national viewpoint, this is not as great a problem as it once was: improved forecasting has enabled power management planning to accurately predict wind energy volumes one day in advance, allowing wind power to be more easily integrated into the mix of power generation sources. As wind turbines are installed across the country, a lull in wind in one area may be compensated by higher winds 38
elsewhere. Consequently, it has been found that 1,000MW of installed wind power can replace 300MW of power from a coal or gas-fired power station. In the future, large wind farms will be combined with an energy storage system, such as creating hydrogen through electrolysis, then using fuel cells to convert the hydrogen back into electricity on demand. Combining wind power with a hydroelectric pumped storage facility, where water is pumped from a lower level to an upper reservoir when supply is greater than demand and then released when demand is higher, is also an effective way of creating a more constant power source from wind. If you are planning a wind turbine for your own micro-generation project, you have two choices. You can either feed your power directly into the grid and not have to worry about peaks and troughs, or you can use your wind turbine to charge a bank of batteries, thereby smoothing out the peaks and troughs of supply and demand to provide your own reliable power source.
Small Wind From a micro-power perspective, small wind systems are defined as wind turbines with a peak capacity of 100kW or less. 100kW is still a substantial amount of power, capable of powering a small village. In reality, most micro-power wind projects are a fraction of this size, either providing power for one home or a rural business such as a farm, or providing an even smaller amount of power for an off-grid application in a remote location. Farmers are switching on to the commercial benefits of installing small wind turbines on their land. The cost savings can be quite substantial and a well-positioned wind turbine can not only provide most of the electricity a farm uses but pay for itself in just a few years. This photograph shows a 50kW wind turbine. The tower is 25 metres (80 feet) tall. 39
Simplified anatomy of a wind turbine 1 3 4
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The Rotor spins as it catches the wind. In small micro-power turbines, this rotor is often a fixed pitch design, configured for a specific wind speed. In larger systems, the rotor is a variable pitch, which can adjust itself to match the speed of the wind. The aerodynamics of the Nose Cone reduce turbulence around the turbine head. On a variable pitch rotor system, the mechanics for the variable pitch are mounted inside the nose cone. The Nacelle contains the power generator, a gearbox (where used) and, on larger wind turbines, a braking system so that the rotors can be halted if wind speeds get dangerously high or for carrying out servicing. Most of the smaller wind turbines have a Tail Boom so that the turbine can face into the wind. The wind turbine needs to be able to turn to face into the wind. This is known as yawing. The Tail is used on smaller wind turbines to face the turbine into the wind. This is known as passive yawing. Larger wind
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turbines are turned into the wind using a motor, known as a yaw drive. This is known as active yawing. The Yaw Bearing enables the wind turbine to yaw. These are extremely strong bearings that are capable of handling very high loads: not just the weight of the nacelle and rotor, but also the wind force on the turbine. In an active yawing system, the yaw drive is also mounted at this point. The tower can be as simple as a pole or may be an extremely complicated tower. Like the yaw bearing, the tower must be capable of handling very high loads and must be mounted in strong foundations. In many cases, the tower must also be capable of lowering the wind turbine to ground level for inspection and maintenance, or to protect the wind turbine in dangerously high winds.
Inside the Nacelle 1
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Gearbox – used to increase the RPM from the slower speed of the rotors to the faster speed required by the generator – typically around 1,500 revolutions per minute (RPM). Some very small (i.e. sub 1kW) wind turbines do not have a gearbox. Instead, the wind turbines rotate at around 1,000 rpm and power the generator directly. The generator. Also called an alternator. The vast majority of generators produce alternating current (AC) rather than DC. This is true of even very small wind turbines used for charging batteries: a rectifier subsequently converts AC to DC. The brake is used to lock the rotors so they cannot turn in very high winds or for servicing the turbine. On smaller pitch systems, you may not have a mechanical brake. Instead, the system may either have ‘dynamic braking’, which works by shorting out the alternator and locking the turbine in place, or a furling system that turns the rotor blades away from the wind so that they cannot spin too quickly and burn out the generator in stormy weather. Tower.
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Yaw Bearing. In a larger wind turbine, there would be a complete yaw drive and yaw motor mounted here. The wiring leads down the tower to the control equipment at ground level.
Wind Science Wind is created by differences in temperatures and atmospheric pressure. Some of the sun’s energy heats up layers of the earth’s atmosphere. As layers of air warm up, cooler streams of air are drawn in. Temperatures vary around the world, leading to air constantly circulating around the earth. The extremes of temperature in the earth, from the polar icecaps to the tropics, combined with the rotation of the earth on its axis creates global jet streams – massively powerful, fast flowing currents of air, often travelling at hundreds of miles an hour, flowing from west to east around the planet at a height of between four and seven miles. 42
Thank you for reading this extract from Introducing Renewable Energy.
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