Greener boating
Pamela May 2 is an electric-drive trip-boat with batteries charged by eight semi-flexible solar panels. The vessel is operated almost entirely using the solar input, the shore line being connected only when necessary in less favourable weather.
generation electric Alternative Propulsion Boating Group member David Struckett explores the options of solar and wind power on inland waterways craft With the principal aim of promoting a reduction in the use of fossil fuels and their harmful emissions, IWA’s Alternative Propulsion Boating Group has been researching electric drive for inland waterways craft, together with options for power generation (both on and off board) and storage. The topics covered so far have included solar and wind, examined here, together with shore line availability and types of battery storage, for the various cruising boats on our canals and rivers. Existing steel narrowboats, wooden craft and GRP cruisers may present difficult challenges when you’re considering changing the motor from internal combustion to electric drive – but there are many smaller improvements that could also significantly reduce fuel consumption. New or renovated craft, if designed with electric drive and specific choices (note the plural) of energy
source, should aim to be at least ‘net carbon neutral’ – and ideally use no fossil fuels in normal applications. Either way, the improved efficiency that electric drive offers can always be appreciated. In cases where a generator is installed to charge the batteries (sometimes referred to as a ‘serial hybrid’ after motor industry application, as opposed to a ‘parallel hybrid’, which incorporates a conventional engine), there are still choices you can make in terms of types of fuel and technology – a conventional generator adapted for ‘bio’ fuel or powered by a fuel cell, for example. In all cases, however, the possibility of wind or solar power offers the chance to reduce fuel and emissions – possibly to zero.
RUN BY THE SUN Solar panels
While the sun’s energy is free to use, solar panels can present you with a significant upfront cost. Monocrystalline or polycrystalline are the most common types of solar panel available, and usually come fixed in a rigid frame. In practice, polycrystalline panels are slightly less efficient in terms of power per unit area, but are a little cheaper to manufacture. A more expensive alternative – although under continuing development so prices are coming down – are semi-flexible panels, suitable for fixing down onto a curved roof, for example. These are currently between two and four times the price per watt than the rigid types, and require a little more area for each watt generated. They are, however, considerably lighter and, if assembled securely, are durable enough to walk on. They are produced using thin film techniques, sometimes referred to as ‘amorphous’.
Area, power and cost
Solar panels can be fitted to many types of inland craft.
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From current data, the area required is, on average, about 0.5 square decimetres per watt for rigid panels, which is very consistent over the range of about 20W to 360W panels (except a few ‘ideal’ examples that appear slightly lower). It’s worth noting, however, that the nominal power ratings given for the panels are normally the ‘maximum output’ – the amount of energy gathered under ideal sun conditions. This is seldom achieved, of course, but assuming panels are tested under controlled conditions, the ratings are comparable. When installed on a boat, a near-horizontal attitude would face the sky at all times, meaning at least some solar energy can be guaranteed during daylight hours. When moored, however, ensuring the panels are oriented due south and IWA Waterways |
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