DECEMBER 2009

Water; The original green energy
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Click to Enlarge - Although large hydroelectric operations like this one have potential to generate quite a bit of green energy, some believe that even more energy could be harnessed by a large number of smaller facilities.

“There’s a major reexamination of the value of hydropower going on now, particularly over last three or four years. The renewed interest is because of the push for renewable portfolio standards in certain states and how to meet those standards. Hydro is considered green by the states, has a favorable standing with local communities and is very popular. There has been increased attention and a movement to harness what is potentially out there,” said Doug Dixon, technical executive at the Electric Power Research Institute (EPRI). Members of EPRI represent more than 90 percent of the electricity generated and delivered in the United States.

Today, conventional hydroelectric power represents only 7.6 percent of all American electric generation, but the potential waiting to be harnessed is huge. Not in gigantic projects like the Hoover Dam, but in a vast number of smaller, more diverse, nationally distributed sources that cumulatively could add up to big electricity production. Hydro has advantages over solar and wind since it produces full time. The next generation of water power is likely to include:

  • Building additional capacity or increasing efficiency at existing hydroelectric plants.
  • Installing new power plants on existing dams.
  • Building small-scale hydro plants not requiring new dams or reservoirs.
  • Installing ocean-wave and tidal generators.
  • Placing in-stream hydrokinetic turbines in rivers.
  • Harnessing the power of constructed waterways: canals, aqueducts, water supply system, and effluent streams.

Hydropower was the earliest and cleanest source of renewable energy, but not much was heard, if anything, about it in speeches about renewable energy from the presidential candidates. They would talk about wind, solar, biomass, ethanol, electric vehicles; even bring up controversial nuclear, but barely any mention of hydro.

Fred Ayer, executive director of the Low Impact Hydropower Institute (LIHI) characterized the situation this way, “My sense is the public attitude about hydro is mixed. People are conflicted. When they think about it initially, they like the idea it’s renewable. On the other hand, it has the potential to cause serious damage when you insert dams into free-flowing rivers. I don’t think you will see many new dams built in the United States in the near future.”

Rather than build new dams, environmentalists are lobbying to remove them from rivers that have migrating fish such as the salmon in the Columbia River. Besides storing potential energy to generate electricity, people often lose sight of the vital role dams play in flood control, irrigation and creating lakes to store water supplies and for recreational use.

“I think our best hope for additional near term hydro is the powering of non-powered dams. The dam is already there and the environmental impact has either been accepted or mitigated,” ventured Doug Hall, program manager for water energy at the Idaho National Laboratory (INL). Adding capacity to existing hydro plants is another option. Replacing older turbines with newer, more efficient ones can gain significant power output with the same water flow, by as much as 15 percent.

INL is a science-based, applied engineering national laboratory that supports the United States’ Department of Energy’s missions in nuclear and energy research, science and national defense. It is also the leading authority on hydropower’s potential. In 2004, with the assistance of the United States Geological Survey, INL completed a major water energy assessment of all 20 hydrologic regions in the United States.

Anyone is interested in exploring the water power potential in their area should visit http://hydropower.inel.gov/prospector/index.shtml. There, the Virtual Power Prospector geographic information system (GIS) application displays all natural stream water energy resources in the United States. By displaying maps of potential hydro sites and existing infrastructure, detailed information is available.

Based on this study and additional research, INL released its Feasibility Assessment of the Water Energy Resources of the United States for New Low Power and Small Hydro Classes of Hydroelectric Plants. For study purposes, low power was defined as 1 megawatt or less and small hydro from 1 to 30 megawatts. INL estimated the power potential for sites not requiring a dam or reservoir based on using penstocks (a pipe that takes water from a higher elevation to a turbine at a lower elevation).

“Using very conservative assumptions on how much developable hydro power there is available; we identified 130,000 sites in the States that represent 30,000 megawatts of annual average power. Today there are about 2,300 hydroelectric plants in the United States with a cumulative annual average power of about 35,000 megawatts. So, there is the theoretical potential of nearly doubling hydroelectric production,” said Hall. Again, that is without building new dams or reservoirs.

Worldwide during 2008, small hydro installations grew by 28 percent over 2005 to raise the total small hydro capacity to 85 gigawatts (GW). Over 70 percent, or 65 GW of new, small hydro was in China, 3.5 GW in Japan, 3 GW in the States, 3 GW in India and the balance in a number of other countries.

Using water energy that runs through pipes at irrigation projects and water treatment plants is also a greatly underutilized asset. An example of what can be done is found at the Deer Island Wastewater Treatment Plant in Boston. After wastewater is treated, and before it discharges into a 9.5 mile outfall tunnel into Massachusetts Bay, the water drives two, 1,000 kilowatt generators. In August, the project submitted an application for certification to the Low Impact Hydropower Institute. If certified as environmentally responsible, the project may become eligible for carbon trading credits, green energy bonds and can be added to a renewable energy portfolio.

Microhydro, generally defined as less than 100 kilowatts, has experienced a revolution over the past decade, particularly due to technology advances in microturbines that require as little as a few quarts or gallons of water per second to generate electricity. Individuals, both on and off the grid with access to even the smallest water flows are generating their own electricity. Advances in micro circuitry and dropping prices for charge controllers, batteries and small inverters have made this possible. “It’s a niche market, but one that is growing,” said Denis Ledbetter, owner Lo Power Engineering. His company manufactures microturbines costing from $1,800 for a 50 watt unit to $2,150 for 1,500 watts. They use a multi-cupped Pelton design waterwheel mounted inside a metal case that is driven by a jet, or multiple jets of water. The turbine drives a standard automotive alternator to charge a bank of batteries. Once the batteries are charged, DC power can be fed to an inverter for conversion into AC for home use. Without labor, and depending on the size and length of the penstock, complete microturbine systems typically cost in the range of $5,000 to $10,000 dollars.

A telltale sign of what’s happening in a variety of hydro projects is the soaring increase in the number of preliminary permits issued by the Federal Energy Regulatory Commission (FERC). Part of the increase is due to a pilot license program to encourage hydrokinetic and wave energy projects.

A highlight example of FERCs expedited approach is the 100 kW Hastings Minnesota project that was commissioned last August to become the country’s first federally licensed hydrokinetic power plant that is grid-connected. Hydrokinetic is different than a conventional hydroelectric. A turbine placed in a river, man-made channel, tidal flow or ocean current captures energy from moving water at low speeds without requiring a dam or diversionary structure to direct the flow.

FERC approved this first commercial hydrokinetic project at Hastings in December 2008 and it came online nine months later – lightspeed compared to FERC’s traditional standards. This turbine, installed in the flow of the Mississippi River, is generating electricity around the clock except for occasional maintenance. The project is also a prototype for long-term study of the main environmental objection, fish endangerment. A preliminary study conducted by Normandeau Associates, a leading environmental consulting firm, indicated an estimated 97.5 percent fish survival rating for the turbine. Of course, environmental studies will continue during the demonstration phase and the project can be challenged by any number of federal and state agencies or private interests before it can be fully licensed.

Putting low-speed turbines in rivers holds promise for putting clean, renewable electricity onto the grid in a timely manner, if the environmental concerns can be overcome. Infrastructure costs are comparatively low. Turbines can be suspended from anchored barges as done at Hastings, or mounted on the riverbed. Transmission lines can be buried in river beds and major rivers, the most suitable for hydrokinetic, already have robust transmission infrastructure along their banks. Large cities located on rivers with high power demand could be the prime beneficiaries.

“The people at FERC are very aware of the criticism of how long the licensing process takes. They will tell you that if you have projects where no one is particularly concerned about the impact, for example, on man-made canals running downhill where you need to slow down the flow of the water, those kinds of projects could be licensed reasonably quickly,” said Doug Hall at INL. A FERC license typically takes from three to eight years. Because FERC regulates the process, a project is open for review by all the federal resource agencies as well state and local agencies, groups or individuals. This is not the case for wind and solar projects since a FERC license is not required.

“The FERC process is too long, but they try to meet everyone’s needs. Before 1969 we didn’t have many environmental statutes in this country. In the mid to late 80s, FERC started to pay closer attention. The licensing process is certainly not perfect but they are tremendously ahead of where they were 50 years ago. They deal with a lot of important issues that are not always easy to resolve. It can be very time consuming and a very expensive process,” said Fred Ayer at LIHI.

Another FERC sanctioned demonstration project is the Roosevelt Island Tidal Energy (RITE) project in New York City’s East River (a tidal estuary). Over the past 2 years, Verdant Power operated 6 turbines, each with 16-foot diameter rotors to demonstrate the system as an efficient source of renewable energy. Over 9,000 turbine-hours of operation, the system produced 70 megawatt hours that were delivered to two end users. Bidirectionally powered by both ebb and flow tides, turbines are automatically controlled for continuous, unattended operation. Now going into Phase 3, the company plans to build greater capacity through 2012. Because tides run like clockwork, electric production is predictable.

In January, defense contractor Lockheed Martin announced a partnering agreement with Ocean Power Technologies (OPT) to build utility-scale wave generation projects on the Pacific coast. FERC issued preliminary permits for four sites in California and Oregon. These projects will use OPT’s PowerBuoy technology that has been tested in several small demonstration projects, including one with the Navy in Hawaii.

Arrays of PowerBuoys will be anchored offshore. Waves move a buoy up and down and a power take-off system generates AC electricity that is sent to shore on a seabed cable to the grid. Sensors on the buoy monitor subsystems, ocean conditions and real-time data is sent to shore. If waves become too high, the system automatically stops power production. When waves return to normal, power production resumes.

The Energy Improvement and Extension Act of 2008, included a new PCT for marine and hydrokinetic facilities deriving energy from waves, tides; currents in oceans, estuaries and tidal areas; free flowing water in rivers, lakes and streams; free flowing water in irrigation systems, canals, or other man-made channels, or from differentials in ocean temperatures. Such facilities must have a nameplate capacity of at least 150 kilowatts and be in service before January 1, 2012 – a very tight window for hydro development. The corporate tax credit is 1.1 cents per kilowatt hour.

Developers would be further encouraged to build hydropower if they could bank on generous, long term state tax benefits or incentives or renewable energy incentives from utilities.

Everyone constantly decries our dependence on imported oil when the United States has some of the most abundant water resources on the planet. Moving clean hydropower onto the grid in a responsible environmental manner should be a high priority.