A Comparison of New Jersey Tidal Energy Estimates: Georgia Tech Research Corporation and Natural Currents February 20, 2012 Roger Bason, President and Founder Jenai Rohllf, Geologist Natural Currents Energy Services, LLC 24 Roxanne Boulevard Highland, NY 12528 www.naturalcurrents.com
Introduction The Ocean Renewable Energy sector offers great promise to provide clean energy, green jobs and regional economic growth through the production of environmentally benign and economically profitable power generation. US national security and economic health will improve by transforming our coastlines into an environmentally friendly zone that provides naturally renewable energy to accelerate economic growth and national self-sufficiency. To develop this sector, the size and location of the tidal energy resource must be determined to understand its potential for regional development and electric power. After a brief introduction to the various Ocean Renewable technologies and their potential global impact, the focus of the paper is to describe measurement approaches for tidal energy potential and to assess how much tidal energy is available in the estuaries and coastal areas of New Jersey. Two alternative approaches are compared. One study released in June 2011 was completed by Georgia Tech Research Corporation with support from the USDOE. The Natural Currents study was self-funded and also received financial assistance from the NJDOT, Office of Maritime Resources and Office of Research. A Natural Currents estimate of 515 MW of potential tidal energy was presented in 2008 in a report to the NJ DOT Office of Maritime Resources. This was a rough estimate based on a capture of tidal energy across 2.5% (72 km /12 miles) of the New Jersey tidal shoreline (2,884 km / 1,792 miles). The projected output of installing 5,150 Natural Currents 100 kW cross flow tidal turbines would provide a maximum electric power output of 515 MW. During the period of 2010 and 2011, Natural Currents performed site specific surveys of ten (10) sites (Table 2 â€“ Natural Currents Tidal Energy Sites in New Jersey) and identified an additional ten (10) sites of known strong tidal flow speeds that combined identify the top 20 tidal energy sites in New Jersey. Additional factors for potential sites of tidal turbines or fields of turbines in the Natural Currents study included identification of eco-exclusion zones, near shore installation for ease of access, known limitations of 3 MW for grid connections at NJ feeder lines and local project support. A close examination of the tidal power sites in the two studies shows that the potential sites identified are largely complementary. The Natural Currents study indentified tidal site locations near existing infrastructure and power grid interconnections. The Georgia Tech study identified major tidal flows primarily around New Jersey shoreline inlets and the tidal flow out of the Delaware Bay. Using the estimate of 3 MW per site as an average for the 20 sites identified in the Natural Currents study, the complementary location of these sites provides an additional estimate of at least 60 MW to the Georgia Tech study total of 357 MW would provide a 417MW combined total for tidal power potential in New Jersey. This is the most accurate assessment of tidal energy in New Jersey to date. The Georgia Tech Research Corporation performed a coarse, large-scale study for all coastal areas of the United States including Alaska and the Pacific Islands. The estimate for the coastline of New Jersey and Delaware Bay totaled 357 MW. As it did not include areas of the Natural Currents fieldwork, a combined total makes sense as a revised estimate of tidal power potential for the state. 2
The difference in these estimates is due to several factors. The Georgia Tech study was performed as a large-scale coarse estimate of power potential. The analysis was made using mathematically modeled nodes ranging from 300 to 500 meters apart. Natural Currents field studies of ten sites were performed collecting actual tidal data using 1meter bins for tidal water speeds measured with Acoustic Doppler Profiling (ADP) technology. The level of granularity in the Natural Currents field studies was very specific to potential tidal energy sites that were close to grid interconnections. Natural Currents also included estuary river locations that were not measured by the Georgia Tech study but nevertheless are significant tidal sites, closely located to potential grid or dedicated offgrid applications. Generally Ocean Renewable Energy describes five (5) diverse technologies that occupy tidal rivers, estuarine zones and immediate offshore areas. These technologies include: 1. 2. 3. 4. 5.
Offshore Wind Wave Energy Ocean Thermal Energy Conversion (OTEC) Tidal River (Hydrokinetic) Tidal Ocean (Marine Hydrokinetic or MHK)
This paper addresses Marine Hydrokinetic or MHK technologies (items 4 and 5 above) and the application of related technologies to harness flowing waterways generated by near shore coastal tides and flowing waters of rivers impacted by tidal flow patterns. Natural Currents Energy Services, LLC - Background Natural Currents Energy Services, LLC (Natural Currents or NC) has addressed two complementary aspects of Marine Hydrokinetic industry growth by actively pursuing (1) tidal technology testing and (2) tidal site development with equal interest since entering the field in 2001. These efforts include evaluating over 1,000 potential tidal energy sites worldwide during the past decade. A total of 485 potential tidal sites were assessed by Natural Currents around Long Island New York as consultant to LIPA in 2004-2005. The top 20 sites identified are presented in Long Island Tidal and Wave Energy Study: An Assessment of the Resource (January 2007). Natural Currents participated in the design, testing and development of five different types of tidal turbines during this 10-year span. These include demonstration tests of tidal turbines at Roosevelt Island, NY (2002/2003), Shelter Island, NY (2004), Neptune Beach, FL (2005), active flume water tests at the Alden Labs in Holden, MA (2008), advanced system design testing and modifications at the Central Aero-Hydrodynamic Institute (ZAGI) T-2 tunnel in Moscow, Russia (2009 and 2010) with additional field testing completed on the Shrewsbury River, NJ in 2010. During 2011, Natural Currents focused on the re-design of two types of horizontal cross flow tidal turbines to be tested in Europe under the MaRINET (Marine Renewable Infrastructure Network 2012-2016) to meet the evolving European Union tidal equipment standards that will likely define the future tidal energy marketplace worldwide.
Natural Currents achievements during the past decade include: 1.Natural Currents was granted the first Tidal Energy Site Permit in the State when issued NJDEP Waterfront Development Permit (#15525-05-0006.1) on January 14, 2010. 2.Natural Currents was the first MHK project funded by the US Government when it received a line item allocation of $990,000 for the Wards Island Renewable Energy Park in cooperation with the NYC Parks Department as part of EPACT-05 on November 22, 2005. 3.Natural Currents made the first tidal energy presentations to the United Nations Partnership for Small Island Developing States in June 2006. 4.Natural Currents staff presented the first US graduate level courses devoted entirely to tidal energy development at Columbia University School of Public Policy, School of International Public Affairs (SIPA) Center for Energy, Marine Transportation and Public Policy during 2001 to 2003. 5.Natural Currents testimony to the NJ Bureau of Public Utilities (NJ BPU) Energy Master Plan resulted in the highest rating by the Innovative Technologies Working Group on September 19, 2011 among all eleven (11) renewable technologies evaluated. Natural Currents completed a coarse, but fairly accurate estimate of tidal energy potential in a report to the New Jersey DOT, Office of Maritime Resources (2008). It is based on a key assumption that 2.5% (71 km or 12 miles) of the NJ Tidal shoreline (2884 km or 1,792 miles) could be developed for tidal energy production. NC has a known technology in the form of a cross flow tidal turbine that is 14 meters long and can produce 100 kW of tidal energy in a 2.5 to 3.0 meter per second (5 to 6 knot) tidal or river current. The estimate was based on the following; NC 2008 Estimate of Tidal Energy Potential in New Jersey Factor A. 1,792 miles B. 2,884 km C. 2,884,000m D. 72,100m E. 14m F. 140m G. 515 MW H. 5,150 Turbines I. $2.575 B J. $1.030 B K. 10 Years K. 2,060 Jobs
Explanation = miles of tidal shoreline in New Jersey 1 = kilometers of tidal shoreline in New Jersey = meters of tidal shoreline in New Jersey = meters of tidal shoreline using 2.5% of total shoreline = meters long NC 100 kW Sea Dragon cross flow turbine = meters for 1 MW tidal power (10 * 100kW) = Tidal Power Output from 2.5% of NJ Shoreline (D/F) = Number of Turbines necessary to produce 515 MW = Cost to Install 515MW Tidal at $0.5M per System = Labor Cost if 40% of Installed Cost is Labor = Estimated time period to install 515 MW Tidal Power = Jobs Generated (@$50,000/year ave) for 10 years
US Department of Commerce. Coastline of the United States - Length of shoreline to the head of tidewater. NOAA, National Ocean Service. 1939 â€“ 1940. www.infoplease.com/ipa/A0001801.html
Ocean Energy Global Marketplace A number of estimates have been made to predict the overall economic opportunity and power generation that tidal or Ocean Energy can contribute to our collective future at locations worldwide. In 1999 the British House of Commons Technology Assessment Committee stated “if 1/10th of 1% of the energy in the earth’s oceans was converted into electricity, it would supply the world electricity demand five times (5X) over.” To get a sense of overall scale for the Clean Energy Sector, Bloomberg New Energy Research indicates all Clean Energy Investment in 2010 reached $243B, a 30% increase over 2009. The Ocean Renewable sector represents a small but growing portion of this overall investment. A study by Douglas and Westwood (June, 2011) forecast the projected capital expenditure (Capex) on Wave and Tidal energy systems during the period of 2011 – 2015 to be $1.2B based on planned deployments of systems already in the development pipeline for the US, Canada and the UK. This study clearly reveals an historic turning point to an era of commercial growth for Ocean Energy. During this time period the study projects 150 MW of Ocean Energy based on existing pipeline projects (91 MW Tidal, 59 MW Wave). The study identifies the largest market as being the UK, with Canada second and the US third worldwide. A US DOE study reported by Forbes (February 2012) indicated that wave energy along the coastlines of the US could provide fully 50% of US energy needs. This study revealed that available technology wave power could provide 1,170 TW-hrs of electric power or 33%. The Pike Research Report “Hydrokinetic and Ocean Energy” projects a total of 2.4 GW (2,400 MW) of tidal power installed worldwide by 2017. This includes projections in South Korea (750 MW), UK (529 MW), Canada (300 MW), India (200 MW), China (200 MW), New Zealand (200 MW) and Australia (100 MW). This report further analyzes technology and site development for all marine and hydrokinetic resources including wave, tidal, river, ocean currents and ocean thermal gradients (OTEC) to include 760 MW in 2012 and 5,500 MW by 2017. These estimates vary as the studies evaluate different time frames, technologies, and results. However, it is clear that significant growth is predicted for this sector from all estimates and studies. Powerful economic incentives fuel the rapid advance of the emerging tidal energy industry. These incentives are the result of recent policy developments in the UK and Canada providing feed in tariffs with preferred rates for tidal energy production. These include the COMFIT in Nova Scotia ($624 MW-hr) and the UK ($425 MW-hr). US Tidal Assessment – Georgia Tech Research Corporation Study It is critically important to develop and improve upon assessments of the tidal energy resource, as well as identifying the size and location of the resource. The Georgia Tech study identifies tidal energy as one of the fastest growing energy technologies, that it will make a major contribution to carbon free energy and is the most predictable renewable energy resource.
A key element that Natural Currents has championed is the design of tidal energy systems along a coastline that can provide base load power from the tidal flux changes along the coast. This distinguishes tidal energy from intermittent sources such as wind and solar renewable energy systems. The Georgia Tech study presents a well-documented assessment of tidal energy potential for each state of the US based on an advanced ocean circulation numerical model (ROMS). The study also provides a GIS database available that is available to all users over the Internet. (). The study provides a valuable tool to improve our understanding of tidal power opportunities throughout the US including Alaska, Hawaii and the Pacific Islands in a general and coarse scale In the Georgia Tech study, a number of criteria were used to determine tidal potential; • Tidal current velocity and flow rate: the direction, speed and volume of water passing through the site in space and time. • Site characteristics also include: bathymetry, water depth, geology of the seabed and environmental impacts will determine the deployment method needed and the cost of installation. • Electrical grid connection and local cost of electricity: the seafloor cable, distance from the proposed site to a grid access point and the cost of competing sources of electricity will also help determine the viability of an installation. Following the guidelines in the EPRI report for estimating tidal current energy resources (EPRI 2006a), preliminary investigations of the tidal currents can be conducted based on the tidal current predictions provided by NOAA tidal current stations (NOAA, 2008b). There are over 2700 of these stations which are sparsely distributed in inlets, rivers, channels and bays. The kinetic tidal power per unit area, power density, given in this figure were calculated using the equation: Ptide = 1/2 • ρ • V3 Where ρ is the density of water and V is the magnitude of the depth averaged maximum velocity.
Figure 1. Maximum available power per unit area (power density) based on NOAA tidal current predictions in the vicinity of the Savannah River. The diameters of the circles are proportional to the power density. (Haas, Fritz, & French, 2011) Georgia Tech Project Objectives The stated Georgia Tech project objectives included: 1. Utilize an advanced ocean circulation model (ROMS) to predict tidal currents. 2. Compute the tidal harmonic constituents for the tidal velocities and water levels. 3. Validate the velocities and water levels predicted by the model with available data. 4. Build a GIS database of the tidal constituents. 5. Develop GIS tools for dissemination of the data a. A filter based on depth requirements. b. Compute current velocity histograms based on the tidal constituents. c. Compute the available power density (W/m2) based on the velocity d. Use turbine efficiencies to determine the effective power density. e. Compute the total available power within arrays based on turbine parameters. f. Compute the velocity histogram at specified elevations. 6. Develop a web-based interface for accessing the GIS database and using the GIS tools. Technical Description of the ROMS Modeling System The numerical model the Regional Ocean Modeling System (ROMS) is a member of a general class of three-dimensional, free surface, terrain following numerical models that solve three-dimensional Reynolds-averaged Navier-Stokes equations (RANS) using the hydrostatic and Boussinesq assumptions. ROMS uses finite-difference approximations on a horizontal curvilinear Arakawa C 7
grid and vertical stretched terrain-following coordinates. Momentum and scalar advection and diffusive processes are solved using transport equations and an equation of state computes the density field that accounts for temperature, salinity, and suspended-sediment concentrations. The modeling system provides a flexible framework that allows multiple choices for many of the model components such as several options for advection schemes (second order, third order, fourth order, and positive definite), turbulence models, lateral boundary conditions, bottom- and surfaceboundary layer sub models, air-sea fluxes, surface drifters, a nutrient-phytoplankton-zooplankton model, and a fully developed ad joint model for computing model inverses and data assimilation. The model also includes a wetting and drying boundary condition, which is essential for tidal flow simulations. The code is written in Fortran90 and runs in serial mode or on multiple processors using either shared- or distributed-memory architectures. The computational grids were set up and the results were calibrated following the outlines of tidal stream modeling efforts for a regional study. (Haas, Fritz, & French, 2011) Mapping Results of Georgia Tech Study
Figure-2. Presents an overview of the tidal energy sites and grids for US coastlines off Alaska and the Gulf of Mexico.
Figure-3. Computational grids for US East and West Coasts. (Haas, Fritz, & French, 2011)
Figure-4. Georgia Techs Total Theoretical Available Power (MW) from Tidal Streams Along the NJ Coast (Haas, Fritz, & French, 2011)
Table-1. Georgia Tech locations and characteristics of the total theoretical available power along the coast of New Jersey and the Delaware Bay (Haas, Fritz, & French, 2011) Figure-4 presents a summary of New Jersey potential tidal locations identified by the Georgia Tech Research Corporation. The evaluations have coarse granularity and are very broad scale. In contrast to the this study, the Natural Currents evaluation of tidal energy potential made site specific assessments using detailed evaluations of additional locations. These are presented in Figure-5 below as the Natural Currents sites (yellow dots) in addition to the Georgia Tech tidal energy sites (red dots) identified by advanced numerical modeling (ROMS) using supercomputers. Georgia Tech tidal site data is presented in both Table 1 that provides a summary of total power from each of ten sites and Table 3 which presents the location for these sites as shown in the maps below (Figures-5 and 6).
Figure-5. Detail of Southern Jersey and the Cape May Coast
Figure-6. NJ Tidal Energy Sites Identified by Natural Currents (yellow) and Ga Tech (red).
Number - Site 1- Highlands 2- Belmar
Comments Owner / Organization
40.4 -73.99 40.18 -74.02 40.11 -74.05 40.07 -74.04
FERC Permit # 13725
3- Hoffman’sBrielle 4- Wills’ Hole Point Pleasant Beach 5- Point Pleasant Canal 6- Barnegat Light
7- Atlantic City – Margate Bridge 8- Egg Harbor
Manasquan River Point Pleasant Canal Barnegat Inlet
9- Sea Isle
10- Hereford Inlet
12- Cape May Inlet
13- Cape May Harbor 14- Cape May Canal- Rt 162 15- Cape May Canal- RR 16- Boat World
Inter Coastal Cape May Canal Cape May Canal Maurice River
17- Port Norris
18- Greenwich Pier
19- Hancock Harbor 20- Salem City
Cohansey River Salem River
40.07 -74.06 39.76 -74.10 39.38 -74.42 39.29 -74.56 39.15 -74.70 39.02 -74.79 38.98 -74.83 38.95 -74.87 38.95 -74.90 38.96 -74.92 38.96 -74.92 39.25 -75.00 39.23 -75.01 39.38 -75.35 39.37 -75.36 39.58 -75.48
Site at City of Belmar Marina FERC Permit # 13682 FERC Permit # 13247 NJ Maritime Police Station NJ Dept Of Transportation Margate Bridge- Private Owners NJ Dept Of Transportation NJ Dept Of Transportation NJ Dept Of Transportation NJ Dept Of Transportation NJ Dept Of Transportation NJ Dept Of Transportation NJ Dept Of Transportation Short Line Rail Road Bridge FERC Permit # 14222 FERC Permit #14234 Municipal Municipal FERC Permit # 13849 NJ Dept Of Transportation
** FERC = Federal Energy Regulatory Commission
Table-2. Natural Currents Tidal Site Locations per Maps in Figures 5 & 6.
Number - Site 01 – Barnegat 02 – Point Creek 03 – Little Egg 04 – Steelman Bay 05 – Absecon Inlet 06 – Great Egg Harbor Inlet 07 – Corson Inlet 08 – Hereford Inlet 09 – Cape May Inlet 10 – Delaware Bay
Latitude Longitude 39.77 -74.10 39.51 -79.30 39.50 -74.30 39.45 -74.33 39.38 -74.41 39.30 -74.55 39.20 -74.65 39.02 -74.79 38.95 -74.87 38.87 -75.03
Table-3. Georgia Tech tidal site locations - Coast of New Jersey and the Delaware Bay
The following three figures present data collected in the Georgia Tech study that relates to the findings and modeling to tidal flow speeds and patterns along the New Jersey coastline and Delaware Bay. The overall power potential of tidal flow in the Delaware Bay (331 MW) is almost 13 times larger than that estimated by Georgia Tech for the entire coastline of New Jersey (26 MW). The Natural Currents study resulted from the application of local knowledge, specific requests by clients for tidal surveys, map studies and experience on the water. Ten of the 20 top tidal energy sites listed were studied with detailed field research including Acoustic Doppler Profilers (ADP) technology that is highly accurate to within 0.1 cm/sec on tidal speed measurements. Measurements were made through the water column in 1-meter bins from the surface to the seabed. On site bathymetric studies were also performed within 0.03m. Figure-7, Fuigure-8 and Figure-9 present findings from the Georgia Tech study. Figure-7 presents Mean Tidal Current Speeds through a range of 0.3 m/sec to 2.6 m/sec along the New Jersey Coast and Delaware Bay. Figure-8 presents the Mean Kinetic Power Density with a scale ranging from 50 W/m to ~700 W/m. Figure-9 presents Water Depths ranging from <2m (6 feet) to 75m (246 feet) along the New Jersey shoreline.
Figure 7. Mean Current Speed (see key below)(Georgia Tech, 2011)
Figure 8. Mean Kinetic Power Density (see key below) (Georgia Tech, 2011)
Figure 9. Water Depth (see key below) (Georgia Tech, 2011)
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