Tide Turns on Unconventional Hydropower
Dam-free Hydro Taps Power of Waves, Tides, Water Pipes
The sea heaves up, hangs loaded o'er the land,
Breaks there, and buries its tumultuous strength.
Robert Browning, Luria
The world's hydropower is now mostly produced by big, destructive dams. But new technological advances bring promise for a new wave of hydropower projects that leave rivers intact, flood no land, and produce energy around the clock. Tapping the nearly limitless power of the waves, tides, rivers, and constructed water-supply systems has the potential to supply much of the world's power cheaply, efficiently, and with few impacts. Before that can happen, however, technological bugs must be worked out and market barriers removed.
Efforts to harness moving water without building dams have been going on for centuries. The first patent for a device to tap wave energy was issued the year that George Washington became the first president of the United States. Although the world still has not widely tapped the power of the oceans to create electricity, "unconventional" (or dam-free) hydropower developments are gaining ground with pilot projects and research projects around the world.
Most of the attention being given this new field is on the world's oceans, which cover three-quarters of the world’s surface. According to Renewable Energy Access, wave power alone could easily supply the world's energy needs, though much remains to be done to bring it to market. "Research and development of wave energy is still very young in comparison to other forms of renewable energy such as wind power," a May 2007 article in the magazine states. "But wave power – most likely produced by buoys that are anchored two to three miles offshore and move gently up and down with ocean swells – could produce steady and large amounts of electricity. Systems could be scaled up or down in size, whatever is needed to meet demand.”
Areas with high prospects for wave power are the western coasts of Scotland, northern Canada, southern Africa, Australia, and the northeastern and northwestern coasts of the US.
Studies show impressive potential for ocean wave energy sources. Overall potential for wave power is estimated to be at least 8,000 terawatt hours per year of energy (global energy use was about 15 terawatts in 2004), but some experts predict it is likely to supply just 15% of the current global energy demand, once technological advances make it cheaper and more reliable. Electric Power Research Institute calculates that wave energy alone could replace 7% of the total US electricity consumption.
How It Works
There are two broad categories of unconventional hydroelectricity: energy that is generated from ocean waves and energy generated from hydrokinetic sources. Ocean wave energy potential exists near shore and on-shore, and separate technologies exist for each application. There are many sources of hydrokinetic energy with corresponding generation technologies, which include free-flowing rivers and streams, tidal currents and streams, ocean currents, and water movement through constructed waterways such as aqueducts and water-supply pipelines.
Unconventional hydroelectricity technologies do not rely on the conventional methods of impounding water by dams, diverting water, or pumping water into storage facilities. New hydroelectricity technologies can avoid the negative impacts caused by large dams such as displaced people, destroyed habitat, flooded farmland, reduced downstream flows of water and sediment, and released greenhouse gases, among others. There are possible environmental impacts, however, including noise emissions, which can affect marine animals' sonar and reproduction; animal collisions with the devices, and sedimentation and turbidity around the devices. With responsible development, proper siting, and early stakeholder involvement, wave and hydrokinetic energy technologies have the potential to be among the most environmentally friendly power generation sources.
Wave and ocean power have similarities to wind power, but also have some significant benefits over harnessing other renewable energy sources. Wave energy has 15-20 times more available potential energy per square meter of earth than solar or wind power. A 49-foot diameter hydro turbine can generate as much energy as a 197-foot diameter wind turbine. While winds can be erratic, tides can be charted by the minute, which allows power companies to know exactly when the turbines will be generating power. Most unconventional hydro technologies have very little impact on "viewscapes," as they are submerged or barely visible.
Explorations for combining off-shore wind and wave developments into integrated systems have begun. Hybrid offshore wind and wave systems can utilize a shared transmission system, which increases the efficiency of the total system. Combined systems will also increase reliability and reduce maintenance costs.
Energy from Water Pipes
Surprisingly, there is also huge potential to harness hydrokinetic sources of energy from irrigation pipelines, canals and aqueducts – even cooling systems. The total global potential has not been estimated. Free-flowing rivers and streams and tidal areas can also be tapped for dam-free electricity. A report by the Western Governors Association estimates that US western states could get an additional 4,000 MW from turbines in rivers alone, ostensibly with no new dams. The National Hydropower Association also estimates that there is great potential for retrofitting existing dams for hydropower.
Tidal power is another way to tap moving water that has huge potential. One of the beauties of tapping tidal cycles is that they are predictable and reliable. Sixty percent of the world’s population lives near coastal areas, meaning tidal power will generally have shorter transmission distances. Tidal power is, however, intermittent and not steady throughout the day and does not correspond with electricity demands. Places with high tidal ranges are the most effective for harnessing tidal power. Sites that experience tidal change differences of 5 meters (16 feet) or more have the highest potential, but here are limited sites with tidal ranges in this magnitude.
Working the Bugs Out
A new commercial project that eventually intends to supply electricity to 8,000 homes through 300 turbines was installed in May in New York City’s East River. This project reveals the kinds of start-up problems the industry is grappling with. Most seriously, the East River proved more powerful than engineers thought, resulting in turbines breaking and the need for a basic redesign. The New York Times reported that all six of the project's 20-foot-tall turbines, which look like propellers on masts, were shut down for repairs just weeks after the project was inaugurated. The company, Verdant Power, has spent more than $2 million to study the impact its turbines might have on fish in the East River. The site is monitored around the clock to see whether fish are harmed by the blades. So far, it appears that fish tend to swim around the blades, and none have been killed in the project's turbines.
Although the Verdant project reveals some of the technical risks involved for developers, more often the biggest risk is the length and complexity of the permitting process. In July, the US energy regulatory body FERC proposed a change that would grant developers of small tidal projects a six-month pilot license, largely replacing a licensing process can now take up to seven years and cost millions of dollars.
A recent article in the online engineering magazine IEEE Spectrum states, "The best way to commercialize tidal technology is to put turbine systems into the water and test and develop them by trial and error, says William Taylor III, president of Verdant Power, New York City. Without demonstrations, says Taylor, no one will know whether tidal energy really works or how it affects the environment. But until someone can demonstrate that it works, people are loath to invest in the technology.
Removing Market Barriers
Once all technical bugs are worked out, there are still major barriers to widespread development of the world's unconventional hydropower resources. Some of the main barriers include:
Difficultly transmitting power: Many wave-power systems are placed off-shore, making transmission of the energy to end users more difficult than over-land transmission. Areas suitable for wave power are also often far from existing grids.
High research and development costs: Since the technologies are in the early stages, research and development costs are high, with little or no income to support the developer’s efforts. The cost of permits, surveys, and connection to the grid all add to the cost of testing designs and prototypes.
Difficulties surrounding site research and development: Areas and opportunities for research and testing of new technologies are limited. Modeling wave and ocean conditions is difficult, and real world applications are necessary to realize full scale commercial operations to prove survivability, reliability, and scalability. Some suitable sites for testing and installing commercial scale applications are unavailable because access is taken by the testing of immature technologies or site banking. Site banking is the practice of requesting a permit for a particular site, without specific plans to develop the site, in order to keep the competition from developing the site. Merit based competition could limit this barrier.
Lack of investment money: Understanding the energy conversion performance of new technologies is limited and makes it difficult to accurately predict energy output, which creates difficulties in securing financing.
Permitting barriers: Permitting has been cumbersome and expensive. Regulatory agencies do not have policies and protocols to permit the new devices. The procedures they do have are designed for existing technologies that do not necessarily apply to the new technologies. In some cases multiple agencies must participate, and coordination is slow and difficult.
Lack of information on environmental impacts: This could prevent a demonstration project receiving necessary permits from regulatory agencies. Also, marine impact on the technology (such as algae growth) is unknown and may be important to future designs.
The Next Wave
There are over 1,000 patented wave-energy technologies, and many companies working to develop projects. In the US alone, permits have been issued to 26 different companies, with 26 different technologies. It is hard to predict if any technology will come out ahead of others as the industry matures.
Because this emerging industry is still in its infancy, much remains to be worked out to bring it to market. Gregg Kleiner, of Oregon State University’s College of Engineering, says, “It’s kind of like a gold rush right now to see who can come up with the best system.” Technologies differ in scope, technique, design and purpose. Different systems can be placed near shore, off shore, floating or submerged. As more pilot projects and commercial-scale projects are installed, the menu of technologies will dwindle and market leaders will emerge. Unconventional hydro technologies are starting to attract traditional energy companies. According to the East Bay Financial Times, oil giant Chevron will invest up to $2 million in a feasibility study of a wave energy project near the northern California coast.
Unconventional hydroelectricity technologies have the potential to allow communities to decide how their future power is generated. With continued research, development, and deployment more systems will be available to offset the demand for environmentally damaging power generation technologies. The world desperately needs this industry to succeed, to help us solve the problems of the world's growing energy needs in the face of global warming – and to protect the world's rivers.
Case Studies from the World's Coasts
South Africa: In partnership with the Clinton Global Initiative, Finavera Energy, a Canadian wave power company, has committed to develop a 20 MW wave energy project in South Africa, at an estimated cost of $40 million. Profits will go to alleviate poverty with power subsidies to community service centers and investment in rural electrification. The project plan will create accessible decentralized energy and jobs for locals. The project estimates that it will save $2 million/year in fuel costs and will avoid 20,000 tons of CO2 emissions.
The project sponsors are currently collecting environmental data, and initiating site selection. The plan is to employ the company’s AquaBuOy technology to generate 20 MW of power by 2011.
Canada: Students, staff, and administrators at Pearson College of the Pacific in British Columbia (BC) are behind a deployed tidal power demonstration at Race Rocks Island. The college has a 30-year lease to manage Race Rocks Ecological reserve, an island owned by the BC government that is an environmental reserve.
This community driven project will allow for the testing of the tidal power system in the open ocean. Environmental impacts of the system will be recorded which will increase knowledge of affects for future commercial scale deployments. Students, Clean Current, and BC government agencies will closely monitor environmental impacts of this system.
Two large diesel generators generated electrical power at Race Rocks. The College considered wind and solar technologies that were not feasible.
Clean Current Power Systems approached Pearson College to develop a wave-power project at the Race Rocks site. Generated electricity will transmit to the island through a buried cable in the seabed. The first power was generated in December 2006.
Alaska: A proposed coal plant for the city of Seward drove members of the Resurrection Bay Conservation Alliance to look for cleaner energy alternatives. In addition to directly opposing the coal plant, the group put together a proposal on wind, tidal and hydropower alternatives, and presented it to the City Council. The council then voted down the coal project.
The Alliance first proposed traditional hydroelectric power system on a local creek in their alternatives plan, but things got more interesting after they were contacted by a hydrokinetic energy firm. The firm, with offices in Slovakia and Austria, produces the StauDruckMachine, which is put directly in rivers, streams, creeks, canals, and channels. The system has a fish passage system. The company is now working to determine the specifics of potential sites in Seward.