Abstract

On behalf of the Energy Development and Power Generation Committee, welcome to this Panel Session on Harnessing the Untapped Energy Potential of the Oceans: Tidal, Wave, Currents and OTEC. Renewable energy sources from the oceans include offshore wind, wave energy, tidal energy, OTEC and underwater currents. Harvesting ocean energy is not a new concept, yet it has remained a marginal resource. Today there is serious interest in offshore technology in Europe, Asia and the United States. Wind farm technology has moved offshore where the prevailing winds can be more consistent and out of sight. Offshore wind energy is the fastest growing sector in renewable energy. Capacity by 2010 is projected to grow to at least 2000 MW. Areas of great tidal differences produce regular and predictable tidal currents of 5 knots or more, creating tremendous energy potentials. France has had a 240MW tidal power generating facility for 40 years. Projects harnessing tidal currents have shifted toward capturing tidal-driven coastal currents. A study of 106 possible locations in the EU countries for tidal turbines showed that such sites could generate power on the order of 50 TWh per year. Compared with the largest wind turbine operating or planned today (4.5MW), the power output as well as the size of a marine current turbine is extremely promising. The first commercial-scale wave power facility turning wave energy into compressed air was established in Scotland. Some proposed schemes involve hinged pontoons with hydraulics, while others appear like floating pistons that rise and fall with the wave action. Several prototype demonstrations are planned in the next few years. Growth in this sector is anticipated to reach $100 million per annum by 2010. The difference in temperature between the surface waters and the deeper ocean waters can produce significant thermal energy. The US DOE has been studying OTEC (Ocean Thermal Energy Conversion) in Hawaii for many years. 2 This session will focus on the potential for power production from the oceans, Tidal, Wave, Currents and OTEC. The Panelists and Titles of their Presentations (and Invited Discussers) are: Each Panelist will speak for approximately 20 minutes. Each presentation will be discussed immediately following the respective presentation. There will be a further opportunity for discussion of the presentations following the final presentation. The Panel Session has been organized by Peter Meisen (GENI, CA, USA) and Tom Hammons, (University of Glasgow, UK). The Panel Session is moderated by Tom Hammons and Peter Meisen. The first presentation is on Ocean Wave and Tidal Power Generation Projects in San Francisco. . It will be presented by Peter O'Donnell, Sr. Energy Specialist, Manager Generation Solar & Renewables Programs, SF Environment Organization, CA, USA. San Francisco sits on a hilly peninsula with the Pacific Ocean and six miles of sandy beach along its western shore. The narrow Golden Gate passage stretches for almost three miles along its northern coast, leading into the deep water San Francisco Bay along its northern and eastern shore. These ocean waves and the Bay tides, combine to create two first-class renewable energy resources -tidal currents and offshore ocean waves. These are two distinctly different resources -tidal currents are driven primarily by the gravitational pull of the moon and are independent of sun, rain and other local weather conditions. Long rolling ocean waves are a condensed form of wind energy, blowing out of the northwest across the Pacific Ocean. How San Francisco is harvesting this Energy will be discussed. The Electric Power Research Institute (EPRI) and EPRIsolutions are conducting collaborative power production feasibility definition studies on offshore wave energy and tidal current energy on behalf of a number of public and private entities. The outcome of the offshore wave study, which began in 2004, is a compelling techno-economic case for investing in the research, development and demonstration (RD&D) of technology to convert the kinetic energy of ocean waves into electricity. The tidal current studies began in early 2005 and are currently at the site identification and device assessment stage). Techno-economic results for tidal plant designs at various sites are expected in late 2005. In the presentation, this will be introduced, described and discussed. Peter O'Donnell is Manager Generation Omar Siddiqui is a Senior Associate at EPRIsolutions, a subsidiary of EPRI that provides application services based on EPRI R&D products and management consulting services to the energy industry. He has over 10 years of experience in the energy sector and provides expertise in electro technologies, financial analysis, energy efficiency, program design, and planning. Mr. Siddiqui is currently the project manager for both the EPRI-Global Offshore Wave-and Tidal Flow-Power Feasibility Assessments He also manages a variety of other projects for Global Energy Partners, with a focus on assessments of end-use electro technologies for electric utilities to advance beneficial electrification. Omar Siddiqui holds a B.S. in Chemical Engineering from Stanford University and an M.B.A. from the Anderson School at U.C.L.A. Roger Bedard has over thirty-five years of experience in developing and managing medium size ($500K -$10M) engineering development projects. He has successfully managed many renewable energy demonstration projects including solar thermal heating, solar thermal electric (both line and point focus) and solar photovoltaic combined electricity and process heat (line tracking PV system where PV cell coolant was used for process heat) projects. His renewable energy experience was gained in three different career positions over the past twenty-five years. Roger Bedard holds a B.S. in Mechanical Engineering from the University of Rhode Island and a M.S. in Mechanical Engineering from the University of Southern California. The third presentation is an invited discussion on Wave and Tidal Stream Energy Outlook from the UK and will be given by on Andrew Mill, Managing Director European Marine Energy Centre, UK. The UK's heritage in marine energy conversion research began in the 1970s. Edinburgh developers Ocean Power Delivery have recently begun generating electricity at sea off the Orkney islands from their prototype 750kW Pelamis. It was the world's first far-shore wave device delivering network electricity. The UK's research and manufacturing base are at the forefront of the resurgence of interest in marine energy with a number of projects under way. 4 This presentation reviews the progress to date in the UK on development of devices, standards and test facilities. It describes the world-leading European Marine Energy Centre (EMEC) on Orkney. It is a purpose built, multi-berth, network-connected and instrumented wave energy test facility that can accommodate up to four separate full-scale devices each rated up to 2.4MW. It is currently embarking on a project to build a complimentary tidal test facility for full-scale devices. This presentation will review the need for standards, what standards and codes are required, and how they may be developed. The UK has already started work in this area and is looking to develop a scheme for certification in the longer term. Andrew Mill will consider where the industry is to day and put forward a model for certification that will ensure that the industry sets the level of regulation while ensuring that the other stakeholders buy in. It will also look at the wind industry model for regulation and draw upon this to identify the needs of the marine industry. Finally, it will look to identify what stakeholders require from regulation and how the device developers can best meet that, test houses and other stakeholders working together. The oceans contain a vast amount of mechanical energy in form of ocean waves and tides. The high density of oscillating water results in high energy densities, making it a favorable form of hydropower. The total U.S. available incident wave energy flux is about 2,300 TWh/yr. The DOE Energy Information Energy (EIA) estimates 2003 hydroelectric generation to be about 270 TWh, which is a little more than a tenth of the offshore wave energy flux into the U.S. The fact that good wave and tidal energy resources can be found in close proximity to population centers and technologies being developed to harness the resource have a low visual profile, makes this an attractive source of energy. Recent advances in offshore oil exploration technology and remote management of power generation systems have enabled significant progress in advancing technology development by simple technology transfer. A few systems have made it to full-scale prototype stage allowing experience to be gained from operational aspects, which is a critical aspect to develop economic models. However, despite enormous progress over the past 5 years, current and wave power conversion technologies are at an immature stage of development. A lack of accepted standards, a wide range of technical approaches and large uncertainties on performance and cost of these systems show this. Further RD&D and the creation of early adopter markets through government subsidies is required to move these technologies into a competitive market place. International treaties related to climate control have triggered resurgence in development of renewable ocean energy technologies. Several demonstration projects in tidal power are scheduled to capture the tidal-generated coastal currents. Commercial-scale wave power stations exist and are delivering power to national grids. Offshore wind farms are delivering energy to shore. As government policies shift towards inclusion of renewable sources, the near shore ocean resources have tremendous potential. Worldwide investments in renewable energy technologies reveals that offshore wind energy is the fastest growing sectors. Strong growth in offshore wind power installations is anticipated over the next decade. In 2000, development of systems to capture wave energy reached a milestone with the commissioning of the first commercial-scale power facility in Scotland. Technical capabilities, both engineering and management, exist in the offshore sector to undertake the size of projects envisioned. Harnessing the untapped potential of ocean energy has commenced. In this presentation the progress to date and future plans and prospects will be evaluated and discussed. Andrew Mirko Previsic Anthony Jones was born in California, USA and holds a doctorate in oceanography from the University of Hawaii. His employment experience includes the U.S. Department of Energy Lawrence Berkeley Laboratory, the International Seabed Authority, and Oases International. His research interest is in coupling of marine renewable energy to seawater desalination to provide sustainable source of potable water. Dr. Tony Jones is a senior oceanography with oceanUS consulting in San Francisco. He has been a consultant to various marine renewable energy developers including SeaVolt Technologies, a winner of the UK Carbon Trust's Marine Energy Challenge. Dr. Jones holds patents in salinity gradient power technology and is widely published in the field including a seminal paper on economic forecast for ocean energy over the next decade. Adam Westwood manages DWL's World Offshore Wind, World Onshore Wind, and World Offshore Wave & Tidal project databases. He is author of The World Offshore Renewable Energy Report commissioned by the UK Department of Trade & Industry, and for Scottish Enterprise Renewable Energy Spends & Trends. Past research activity also includes offshore renewable energy studies for major international companies and work on renewable energy industry business prospects worldwide. Projects also include work for the DTI and investment trust 3i relating to financing of a wind turbine installation vessel. Published work also includes a number of papers and articles on renewables and he is a regular contributor to renewable energy trade journals. PANEL SESSION SUMMARIES 6 OCEAN WAVE AND TIDAL POWER GENERATION PROJECTS IN SAN FRANCISCO (PAPER 05GM1060) Peter O'Donnell, Sr. Energy Specialist, Manager Generation Solar & Renewables Programs, SF Environment Organization, CA, USA Summary San Francisco sits on a hilly peninsula with the Pacific Ocean and six miles of sandy beach along its western shore. The narrow Golden Gate passage stretches for almost three miles along its northern coast, leading into the deep water San Francisco Bay along its northern and eastern shore. These ocean waves and the Bay tides, pushed by the Sacramento River flowing down from the Sierra Nevada Mountains, combine to create two world-class renewable energy resources -tidal currents and offshore ocean waves. These are two distinctly different resources -tidal currents are driven primarily by the gravitational pull of the moon and are independent of sun, rain and other local weather conditions. Long rolling ocean waves are a condensed form of wind energy, blowing out of the northwest across the Pacific Ocean. Location, location, location -it's the first rule of real estate. It's also the first rule for renewable energy projects -you have to go where the resource is accessible, with supporting infrastructure and grid access, and where a supportive community welcomes your project. Otherwise, shortsighted parochial interests reign and nothing gets done. The citizens of San Francisco support renewable energy, having voted for the City to spend up to $100 million in bond financing for renewable projects. While no public money has yet been invested, San Francisco is preparing to launch two types of renewable energy projects in 2005 -a pilot demonstration for tidal power in May '05 and a first U.S. commercial installation for wave energy that is expected to be producing up to 750kW by 2007. Combined, both projects could then be expanded in prudent phases to provide a significant portion of San Francisco's current 840MW peak demand. More importantly, San Francisco would be modeling these technologies for environmentally safe implementation in coastal and riverine communities round the world. Both ocean wave and tidal current renewable energy generation technologies are due to be revolutionized in the next ten years. These technologies should be ready for large-scale commercial implementation about the time that the North Sea natural gas reserves are depleted in the next ten years. Tidal Power: The tidal current technology that San Francisco is considering has emerged from the physics lab at Imperial College in London, England, evolved over eight years by Dr. Geoff Rochester and Dr. John Hassard. The company, HydroVenturi, London, England, (www.HydroVenturi.com) has piloted its approach in a 150kW configuration in the Humber River, three hours north of London. The HydroVenturi value proposition --no moving parts underwater -promises marginal if any impacts on plankton, fish, and marine creatures. The HydroVenturi tidal power device comprised a cube of venture tubes or wings attached to the marine bottom on a rack safely sited 18m below the water surface and outside the navigation channel in the Golden Gate Passage. The tidal current flowing through the device is accelerated through the Venturi tubes to create a 2.5kg pressure drop, thus creating suction enough to pull air down to a storage tank integrated into the cube below the Venturi tubes. The compressed air is then pushed through a pipe to an onshore air turbine to produce electricity. 7 The first phase of the San Francisco tidal project with HydroVenturi is planned for May '05, and will utilize a barge moored in the tidal flow from which several HydroVenturi tubes will be suspended to harvest tidal current energy. An air turbine on the barge will produce electricity as a proof of concept for skeptical environmentalists, state and federal agencies. With the technology demonstrated and made familiar, the permitting and environmental impact study process will be the next required steps, and which are anticipated to require two years to complete. A one Megawatt HydroVenturi installation could be completed and grid connected by 2008, with expansion to be phased in 5-20 Megawatt increments. A single Megawatt HydroVenturi cube of Venturi wings (see illustration one) measures 23-meters across the bi-directional tidal glow, by 10-meters by 13-meters. The on-shore air turbines in this commercial phase may be housed in a secure facility near the Golden Gate Bridge. Several other tidal generation sites have been selected to serve the nearby communities of Marin County and Oakland. Wave Power: Ocean Power Delivery, Edinburgh, Scotland, (www.OceanPD.com) manufactures the Pelamis wave power generation device, rated at 750kW. Its first commercial installation on the Orkney Islands grid above Scotland was completed September '03. This technical approach has evolved after almost ten years of scale model tank tests, pilots, and field trials. The original design was tailored for the North Sea wave regime. Suitability for the San Francisco wave resource requires that the device be expanded by 10m in length. Wave power can be harvested by a variety of methods and devices, with several unique approaches nearing commercialization. San Francisco, however, can only explore technology already developed to a commercial stage, as public funds cannot be applied to RR&D projects. This said, almost all wave energy conversion devices take advantage of hydraulic pumps and turbines to generate power. The Pelamis approach was selected after an Offshore Wave Power Feasibility Study performed by EPRI and completed in December '04. As the EPRI report will be presented at the June '05 IEEE proceedings, this paper will emphasize tidal current issues, a topic which EPRI will begin assessment of in March '05. The Pelamis device consists of a total of four cylindrical sections, which are connected together by three hydraulic power conversion modules, for seven sections in all. The total length of the device is 120m and device diameter is 4.6m. Each power conversion module comprises hour hydraulic rams (two heave, two sway); high-pressure accumulators for power smoothing storage; two variable displacement motors for power conversion; two 125kW generators revolving at speeds of 1500rpm; and an integrated transformer to send AC power to shore by a shielded cable. The power conversion modules are constructed and shipped from Scotland, while the interconnecting tubes are constructed locally of steel, and eventually can be made from marine-grade cement. The Pelamis device, named after a sea goddess, is secured by a compliant slack moored anchoring system. The device is bright red in color, observable from one nautical mile away, and well marked for radar detection by passing ships. It is ballasted by sand to ride semi-submerged in the waves. See streaming video at www.OceanPD.com. The device will be sited in an area outside the shipping channel, and about six miles offshore from the San Francisco coastline. At a later date, a series of these devices can be installed to comprise a wave farm. By employing the Pelamis device, a generation capacity of 35 Megawatts per mile is anticipated, and additional device optimization is anticipated. While renewable energy and power production is one goal of these projects, the City and County of San Francisco is equally interested in becoming a center of excellence 8 for the implementation of these technologies to a world market. Local job creation and the establishment of a Green Business Park focusing on renewable energy technologies is another goal of the City. In summary, San Francisco's interest in the HydroVenturi approach is due to the vaklue proposition of no moving parts underwater, compared to the underwater turbines of a LaRance River-type saltwater entranement, or a Blue Energy or Verdant Power (see www.VerdantPower.com) vertical or horizontal axis-type propeller installation. A technology with no moving parts underwater makes tidal power attractive to San Francisco's well-established environmental community. This approach is viewed as the most environmentally benign for the Bay Area's endangered salmon runs, delta smelt, anchovies, dolphins, whales, seals, sea lions, and benthic creatures, other fish species and marine mammals. For these reasons, San Francisco believes the time has come to harvest the City's tidal and ocean wave resources. Renewable energy development also creates jobs for the local community, at an anticipated rate of 10 jobs per Megawatt. Harvesting San Francisco's Renewable Tidal Current Resource The HydroVenturi approach has value in run of river applications in the Mississippi, Missouri, Ohio and other riverine communities. In the next decade, many new bridge constructions at significant current flow locations may well integrate renewable energy generation schemes. This technical advancement has the potential to make tidal current power production environmentally benign for endangered salmon runs, other fish and marine mammals as well. Tidal current is in abundance in San Francisco's Golden Gate passage and at other Bay locations. Tidal current is generated by the gravitational pull of the moon, and to some extent the sun, on the Bay's surface, pushing some eight billion gallons of water up the Bay and pulling it back out to the Pacific Ocean in six-hour cycles. More than 40% of California's fresh water eventually flows through the Golden Gate passage. This tidal current resource has been equated to a 240-mph-hurricane-force wind, yet it remains often overlooked. Experts consider San Francisco one of the top 10 locations for developing tidal power. For such reasons as municipal commitment to renewable energy production combined with strict environmental oversight, San Francisco may well be the best site in North America for a first commercial installation of "nomoving-parts" technology. c) Where the maximum pressure drop occurs, air or water is sucked from the surface through a system of pipes. The suction created in this circuit is sufficient to drive onshore air turbines. Regardless of the specific underwater construction, an on-shore tidal power facility would comprise a continuous control and monitoring station, office, maintenance area, interpretive center, shrouded air turbines, sub-station and a few miles of underground cable to deliver this power to the grid. The following is useful when comparing tidal power to other renewable energy resources: Benefits: • Tidal current is predictable and regular • Tidal power is independent of weather conditions and fuel purchases • Tidal power generation is not affected by climate change, lack of rain or snowmelt • The San Francisco Bay tidal resource could exceed 2,500MW • Environmental and physical impacts, and visual pollution, are expected to be small • Tidal power is ideally placed to support hydrogen production and desalination Concerns: • Tidal power generation is in its infancy • Tidal power generation per day has four slack tide periods of no power production for up to 90-minutes every 24-hours Why San Francisco? Located at the tip of a peninsula, San Francisco has already experienced a series of electrical power outages in the winter of 2000. San Francisco is committed to shutting down its old, fossil-fuel burning power plants and to improve local and regional air quality. San Francisco has demonstrated the political will to support renewable energy with bond financing. San Francisco has the infrastructure to showcase tidal power beside the landmark Golden Gate Bridge to the many international visitors who will want to attend annual ocean energy symposiums, and perhaps purchase ocean energy systems. The global opportunity for ocean energy is huge and San Francisco can grow to become a center of technical expertise. Tidal Power History Tidal and river power are not new. River current has been used to drive mill wheels that grind grain in Britain and France from the 11 th century. In the 1960s at LaRance, France commissioned the first commercial tidal barrage system using ten 240kW bulb turbines. The U.S. Congressional record notes that President John F. Kennedy, one month before his death, suggested an estuary in New England be evaluated for a barrage system. In the early 1980s, the Canadian government's National Resource Council spent about six million dollars for tank tests and in-river trials of the Davis vertical-axis turbine system. See www.blueenergy.com. The European Commission has also sponsored research projects. In Canada, the design work and pilot trials emphasized vertical axis turbine designs rather than horizontal propeller designs. However, vertical axis turbines, while stronger, expend half the energy of their rotor arc working against the resource. This is not efficient. Equally, propeller designs have moving parts underwater, must be geared to adjust to address the oncoming current flow, and in a "farm" configuration could create a navigational hazard. Pilots and evaluations are continuing in the UK, Canada, and 10 Alaska's Yukon River. The trend is toward new designs that emphasize minimal civil works and a small ecological footprint. Resource Potential Conservatively, an average 3-knot tidal current flows through the Golden Gate passage and at other points in the Bay. While sailors speak of five and six knot currents at spring tides, it is better to under-promise and over-deliver in resource projections. Properly harnessed, the Bay's tidal power potential could exceed 2,500MW, about three times San Francisco's daily peak of 840MW. Worldwide, San Francisco's resource is a drop in the bucket. The global ocean energy resource is estimated at about four million Megawatts. Properly harnessed, annual production could exceed about 15% of world electricity consumption anticipated in 2020. Many opportunistic sites have yet to be examined or surveyed. The World Bank has projected developing countries will need five million megawatts of new electrical capacity by 2040, and tidal current generation may be a wellsuited opportunity. 2.3 The Advantages of Tidal Power Predictability: As a renewable resource, tidal current flow is very predictable, to within 98% accuracy for decades. Tidal charts are accurate to within minutes, for years ahead. Tidal current is independent of prevailing weather conditions such as wind, fog, rain, and clouds that can impact other renewable generation forecasts. Solar generation is impacted by rain, clouds and fog. Wind turbines are impacted by calm weather, yet tidal cycles are as reliable as the rising of the moon. While solar and wind are valuable renewable resources, neither can be plotted with the predictability of tidal energy, especially n a fiveyear forward contracts market. Thus, reliable amounts of tidal power can be forecast with confidence. This predictability is critical to successful integration of renewable resources into the electrical grid. As an official from the California Dept. of Water Resources, familiar with power purchase contracts, said after reviewing a tidal power proposal: This expands our portfolio of renewable resources; we can always tell the 'peaker' plants when to turn on and turn off. Generation cycle: In San Francisco, high tide follows low tide approximately every six hours. Thus, a tidal power system will generate at "peak" for four periods of about 120 minutes per 24 hours, or up to eight hours per day. It will also generate some power at ramp up and ramp down to high and low tide, in all generating some power for 16-17 hours per day. There is also a midnight-to-six am cycle that might be better used for renewable hydrogen power generation, if combined with electrolysis and desalinization technologies, or simply with de-salinization for drinking water production. Most solar and wind systems generate some power for about five to eight hours per day. Benefits: Tidal current power production has many of the traditional advantages of hydro projects: economies of scale; significant power production; accurate financial modeling; reasonable grid access; ability to leverage existing on-shore infrastructure and civil works. However, 11 high-head hydroelectric dam schemes are no longer in favor due to urban and agricultural demand for freshwater resources; the environmental impacts when narrow gorges and their uplands are flooded; the availability of few remaining desirable sites in the continental US. Except for barrage systems, all tidal power systems -Venturi pipes, fences, propeller towers, collared floating turbines --have the following distinct advantages: 1) Sustainability: On average, a tidal resource generates some power for up to 17 hours/day, contributing to "peak" demand some 78% of the time on an annual average. 2) Low-cost: Tidal power may cost about U.S. two million dollars per Megawatt or about 5-cents/kWh, which makes it very competitive with renewable wind at 3-cents/kWh. While initial capital costs are higher than traditional power plants, there is no follow-on fuel purchase, no air pollution, and projects are engineered for a 50-year life. 3) High density: Water has a power density approximately 180 times greater than wind or air, thus allowing a 1MW tidal system to require approximately one-third the space of a comparable wind generation system. 4) Environmentally benign: Tidal power systems produce no pollution or greenhouse gas emissions. The potential for fish kill may be greater during construction than during operation. Canadian river tests showed no fish kill and no silt flow impediment. Large marine animals -harbor seals, dolphins, whales -instinctively shy away from the pull of underwater intakes and vibration. Salmon runs are projected to pass through the center of the Golden Gate channel. However, longterm monitoring of pilot sites is required. 5) Predictability: Cyclical tidal patterns allow power outputs to be predicted to within 2% far in advance, providing reliable base power for integration with electrical grids. 6) Modular design: Engineered underwater components of a tidal power project can be constructed off-site and brought to the site for installation. Projects can be expanded in a building block approach. Power production begins with the first unit installed; output increases incrementally as units are added. 7) Low maintenance: With no moving parts underwater, maintenance is minimized. However, the pilot project and extensions will be staffed at all times to monitor systems and watch for seaweed fowling, etc. Visual inspection and maintenance, if required, can be performed during four slack tide periods per day, and by remote underwater cameras. 8) Local control: Perhaps the next few decades will be a time in which we are able to build renewable electrical power options that make us no longer dependant on a centralized, fossil-fuel based grid. Sunny climates can harvest solar power; central plains states can harvest wind power; ocean, riverine and bay communities can harvest ocean wave and tidal current power. This will give our communities healthier choices, and long-term price stability and less dependency on oil imports, thus allowing communities to recycle their energy costs and boost their eco0nomies. Job creation, of course, is a factor with one metric suggesting tat each Megawatt of renewable energy can generate 10 jobs. Permit Process and Site Selection 12 The proposed 1MW pilot project for tidal current power generation would be sited along the south side of San Francisco's Golden Gate passage, well out of the required 133-meter navigation channel. However, further site selection research is required. The Federal Energy Regulatory Commission (FERC) is the designated permitting agency, as they permit all hydro projects. Tidal power, however, is so new that some 14 other federal, state, regional and municipal agencies will take a keen interest with right to comment and review plans. A partial list of commenting agencies, plus community-based environmental and land use groups, includes: National Ocean and Atmospheric Agency; Department of the Interior; Department of Energy; US Navy; US Coast Guard; Bar Pilots; California Bureau of Land Management for bay bottom submerged lands jurisdictional assessment and potential lease negotiation; various agencies on mitigation or remediation, if required; and other agencies commenting on their areas of expertise. Additionally, other identified commenting agencies are the California Energy Commission; California Public Utilities Commission; State Lands Bureau; State and Federal fish and game bureaus; California Department of Water Resources; California Water Quality Board. Permits will include: a County land use permit; a waterways encroachment permit; a tidal facility marine lighting permit from the US Coast Guard. A series of community outreach and education events will be required. As one project advisor has stated, even if no one objects the permit and environmental review process will take about two years. In other words, do not hold your breath. However, in San Francisco, early and repeated education, TV new stories, printed articles and outreach events have paved the way to community support. Even key environmental groups support these projects in principle, though they reserve the right to comment based on a final review of environmental impact studies. Other Issues Marine creature impacts: Protection of winter-run and spring-run Chinook salmon, an endangered species, is mandatory in California. Salmon may select to remain in the wider navigation channel and avoid a tidal power project. Intakes would be screened to protect larger species and avoid floating debris. Air quality impacts: Since no combustion occurs in tidal power projects, there are no emissions. Every MWh of electricity generated by a tidal power project offsets the equivalent of 500 -1,000kg. carbon dioxide, up to seven kilograms of sulfur and nitrogen oxides and particulates, 0.1 kilogram of trace metals (e.g., mercury), and more than 200kg. of solid waste pollution. Navigation channel impacts: A tidal generation project must be sited well clear of the charted navigation channel and pose no threat to shipping or recreation craft. It must be marked and lighted in accordance with US Coast Guard standards. It must be secured to the marine bottom, probably with screw-pilings and secured to a racking system, in a method that assures no threat to nearby bridges and civil works. Site Selection Survey requirements: Data requirements for site selection can require all of the following: a) Class 1 pre-dredge hydrographic survey, though dredging may not be required in construction; 13 b) side-scan and multi-beam sonar surveys dredge volume computations (if required) sub-bottom profiling and seismic surveys vibracoring and gravity coring dye and drogue studies monitoring of currents, waves and tides cross-sectional profiles 3-D charting bathymetric contour chart isopach (sediment thickness) maps site characterization and clearance geological mapping sand resource mapping other topographic surveys, geological surveys, hydrographic surveys and site strata analysis hydrographic survey for volumetric flow rates computer modeling & analysis Pilot Installation HydroVenturi is a spinout from Imperial College, University of London. Its patented system uses a series of open pipes that narrow to create a venturi effect and accelerate current flow. By accelerating flow through the choke (venturi), water pressure within the venturi becomes lower than ambient (a pressure drop creates a siphon effect). The resulting pressure gradient is then harnessed to drive a conventional pipeline turbine. The technique concentrates the tidal energy in the current flow and accelerates a smaller quantity of water into another water pipe or secondary circuit. This circuit then drives a third circuit of air to drive on-shore air turbines and produce electrical power. The advantages of the approach are a lack of moving parts underwater, a step-up of the kinetic energy in the primary tidal flow, and the use of air turbines located on-shore for ease of maintenance. HydroVenturi has built, tested and modeled a 0.6m aperture tidal power system in Grimsby, England. 14 Illustration 2: The HydroVenturi alpha test unit being sited in Grimsby, England, comprises a traditional Venturi tube with air storage tank integrated on the left. The Grimsby site is operated as an R&D facility for improvements on system efficiencies. As third generation technology, HydroVenturi is not a barrage system that floods environmentally sensitive estuaries. It is not a submerged turbine or propeller system with moving parts or underwater generators. Many of the environmental and marine creature concerns are thus eliminated. Managing Community Outreach San Francisco's Department of the Environment has taken a proactive approach to educating community and environmental groups on tidal power technology. Several such groups were asked to submit written questions about the planned technical approach. Written replies were then drafted by HydroVenturi and presented in community outreach meetings for discussion by SF Environment. The questions and answers follow: 1. What are the dimensions of the Hydro Venturi system (modules) required for a 1 MW pilot project? What volume will they displace? The answer depends on the site, particularly the currents and the tides. Let's assume a about 1 MW installed capacity, not 1 MW average output. For sites HydroVenturi has studied in the San Francisco Bay area, an "open-ocean" device is proposed, to differentiate it from the causeway insertions planned for sites in Iceland. The engineering assumption is that the current is high enough for a one-meter head to be generated across the Venturis by their resistance to the flow --not a difficulty in the fast waters in San Francisco Bay. This head would be over a 50-foot distance in the direction of the water flow and would not be easily visible except with sensitive measuring devices. In a nominal system, HydroVenturi need 25x16x25 cubic meters per installed MW in the open ocean. The 16-meter face is in the direction of flow, so this system presents 25x25-meters to the tidal stream. HydroVernturi continues to refine the components of its technology. The company is confident there are ways to reduce this size by as much as 20% in both 'transverse' dimensions, but this is not yet proven. To first order, where the water has a good velocity profile in depth, the area is what counts. This water roughly corresponds to 1.5-m/per second velocity. If velocity accelerates to 2.5-m/per second, generation increases from one Megawatt to to 4.6 Megawatts. An increase to 3.5-m/per second (maximum velocity in the Bay), then the system could generate 12 Megawatts. Power output is approximately at the cube of the water speed. If the very fastest waters are chosen for siting, then the unit can be scaled down considerably in all dimensions; however this may not be the best approach strategically. For example, if the water averaged 3.5-m/per second, then the nominal one Megawatt 'cube' would be less than 10x10-meters in face area. On-shore air turbines, air pipe connections, and a seated 'cube' of Venturi wings with underwater air storage comprise the components. The 'cube' will be sited on a rack secured by pilings into the marine bottom down to near bedrock. In the nominal case: Displacement is 341,000 cu. ft. 2. What material are the modules made of? 15 Concrete is much more expensive than steel. Steel is less durable than concrete. It is difficult to estimate the lifetime of deep-sea modules made of steel since this will depend on site-specific issues, most importantly pebble and gravel scouring. The Grimsby Venturi system, which has been running intermittently since last June 2002, gives a clue about the durability of steel in these conditions. For the pilot project, an all steel cube will be used to offer ease of construction and modification. It will sit on a steel plinth. The second system will almost certainly sit on a concrete plinth, and gravel will be diverted away from the system. Steel in German Battleships sunk in Scottish water has survived relatively intact over the last 90 years. Pilings will be made of steel and concrete, but do not have significant survivability issues. 3. How deep must the system (the modules) be submerged under water? The effectiveness of the HydroVenturi system increases with depth for a given water speed. This is because when the Venturis entrain air, the air/water flow volume ratio is what limits the entrainment capacity. As air is a compressible fluid, it follows that the air mass flow rate, which is what counts when considering the drive to the turbine, increases with depth. However, generally the water is faster near the surface, and this compensates somewhat. In general, the cubes will work at any depth, but for safety, they will be submerged to a depth of at least 16-meters as dictated by the U.S. Coast Guard, in order to provide unhampered use of the water above by commercial vessels, recreational craft, and wind surfers. Siting may approach a navigation channel but will not impinge upon it, per U.S. Navy, Coast Guard, etc. requirements. 4. How will the modules be anchored to the Bay floor? How and where will power be transferred to the land and existing power grid? Dr. John Hassard replies: If you work out the weight and the force exerted by a typical current, you will find that the weight wins every time. However, to avoid any chance of tidal surges making any movements, a plinth will be secured to the marine bottom, by placing concrete pilings through the mud layers to approach the bedrock. On these pilings will be placed a series of rails upon which to site the cubes. The cubes will have safety grills front and back, and be covered so that nothing may get into the Venturis. The interior gap between Venturi wings is anticipated to be 24-inches. Fingerlings, should they enter the system will pass through safely. Larger salmon up to 24-inches in diameter are assumed to pass through safely. Larger fishes, aquatic mammals and scuba divers will not be able to get into the system, and the perimeter guard grilles will be far enough away that the water speed will be low enough not to cause any scuba diver a difficulty. Detailed marine bottom profiling studies will be required. Best technologies developed in the North Sea are being reviewed. Power, in the form of compressed air in a pipe, will be transferred to shore to sited air turbines within one mile of the cubes. The air, on intake and outflow, will drive air turbines to generate electricity. The site will require power processing and a sub-station, and cabling to a grid inter-tie. . 5. What are the known and suspected impacts on tidal flows and sedimentation rates in the immediate vicinity and in other areas of the Bay? 16 HydroVenturi points out there will be no compression of water, simply an acceleration of water through the cube. Water speed before and after will be almost the same, though it must be noted that it is impossible to extract energy without taking something from the water speed. There may be minor sediment fall out on either sides of the cube in a bidirectional system, which is the planned design. There will be some sediment displacement with the siting of the piers. However, as water can flow through the artificial reef of the cubes, there will also be benefit to marine creatures. There may be some minor scouring of sediment, depending on height from cubes to marine bottom, or none. Note, Dr. Ralph Cheng of the U.S. Geological Survey believes that there will be some site-specific impact on the tidal flow but no impact overall to Bay flow velocities. Certainly with several installations sited, the Bay will be monitored for sedimentation impacts. The system modularity makes environmental impact one of HydroVenturi's strongest suites. Given the cube-law of power from water moving at a given velocity, one can extract a great deal of power with a very small effect on water speed. . 6. What is the anticipated amount of dredging necessary for the construction of the pilot project? The required dredging is simply to site the pilings for the racks. This is very site specific and will be negligible, since the sites where lots of dredging is required are less attractive. For example, in the case of the mud depths between Tiburon and Angle Island, we envisage a subsurface 'bridge' configuration spanning the deeper parts and the deepest mud, with pilings only inserted where there is rock near the surface. State law requires that these be over-engineered to protect in case of earthquake. Should there be a quake, the anticipated land shift is from south to north, along the line of the sited cubes. 7. What impact will the tidal power system will have on salmon runs? On plankton? Other species and their habitat? According to Dr. Hassard, these impacts are expected to be negligible. In discussions with several marine monitoring agencies, it is assumed that most salmon will pass above the artificial reef of the cubes. Going upstream, they are driven to do their business; going downstream they are hungry and seeking open water and bait. Smaller salmon can go through the system with, we believe, not noticing the system (they momentarily speed up, but are forced away from the steel sides by the secondary circuit water entering the primary circuit where they are swimming.) Larger salmon cannot enter. Zooplankton and phytoplankton are assumed to be able to pass through the cubes safety. In the water column, these creatures tend to be near surface in the undisturbed top 16-meters above the Venturi cube. Porpoise and seals will be curious and certainly inspect the artificial reef. Whales, should they enter the Bay, can pass by and will be screened from passing through the system, as will anything larger than about 4-6 inches. Some creatures may enter the system and be accelerated out when the tide starts to run strong. Crabs, etc, may choose to live under the cubes. Construction will include underwater cameras in order to observe these phenomena. Scuba diver inspection is planned at slack tide, which happens four times per 24-hour cycle. HydroVenturi will ensure a failsafe system to avoid any chance of human injury. HydroVenturi is committed to Bay area job creation and project construction in San Francisco, possibly at the City's new proposed Green Business Park in the Bayview 17 Hunter's Pont area. To meet City mandates, a public bid process is anticipated in order to construct the project, and HydroVenturi is expected to partner with a U.S.-based marine construction company in order to better manage this process and associated requirements, should they be the selected technology vendor. As an open and public process, however, San Francisco remains willing to discuss and review technical approaches that are supported by independent third party engineering assessments and which pass the "no moving parts underwater" environmental criteria. In summary, the project must make reliable, renewable electricity at something below 12-cents per kWh; the project may not make sushi. O'Donnell grew up in a beach community across the street from the Gulf of exico on the west coast of Florida. He is a world-class scuba diver and underwater photographer. He graduated from the University of Florida in 1972 with a B.S. Journalism degree. He worked overseas in international advertising in South Africa and Japan for ten years. In California he has founded and developed Software and Internet companies with venture capital support. At San Francisco's Department of the Environment, he manages aver, tidal, and urban wind renewable energy programs as well as marketing and outreach for a residential solar program. REFERENCES The Electric Power Research Institute (EPRI) first published his work on tidal power technologies in 2001. He has published more than 100 Magazine Articles in his career. O'Donnell managed an eight million dollar lighting electro fit program that served more than 4,000 disadvantaged small businesses in San Francisco, saving each about $600 per year, reducing consumption by MWs, and his municipal program was the first to win an Energy Star award from the U.S. Environmental Protection Agency.