Renewable energy development has been a growth industry in recent years, but it accounts for less than 7 percent of the total consumption of energy (8.5 percent of electrical power) in the United States, reports the Wildlife Management Institute. Fifty-one percent of the renewable energy produced is used for electricity; the remainder is largely for transportation and other industrial applications. The Energy Information Administration (EIA) projects that renewable-generated electricity will account for 15.8 percent of total U.S. electricity generation in 2030 fueled largely by incentives from the American Recovery and Reinvestment Act.

At 53 percent, biomass energy makes up the greatest component of renewable energy, although most of that is used for transportation and heating.? Hydroelectric power makes up 36 percent of the entire renewable package, but provides the lion's share of renewable electrical production.? As a percentage of total renewable consumption, hydroelectric is decreasing (down 14 percent between 2006 and 2007) largely due to variation in rain and snowfall.? Wind and geothermal each account for 5 percent of the renewable market, with solar representing only 1 percent.?

Much of the country's wind, geothermal and solar resources are found in the West. According to the Department of the Interior (DOI), the Bureau of Land Management (BLM) has identified about 21 million acres with wind potential in the 11 western states, 29 million acres with solar energy potential in the six southwestern states and 140 million acres with geothermal resource potential in the West and Alaska.? Expanding development to federal public lands and increasing the amount of renewably generated power are priorities for the Obama Administration (see related article in this month's ONB).? Following are more detailed overviews of these sectors of the renewable energy industry.

Wind power

The growth in renewable energy has been buoyed largely by the rapid increase in industrial wind power generation.? The installed capacity of wind farms grew by 50 percent in 2008 and there now is more than 28,000 megawatts (MW) of producing wind projects in the United States.? That is enough to serve in excess of 8 million homes.? In the first quarter of 2009 alone, more than 2,800 MW of new generating capacity came online; it is the fastest growing energy sector in the nation and provided 42 percent of the entire new power-producing capacity added nationally last year.? DOI Secretary Salazar has stated that, if the nation fully pursued all the potential for wind energy on land and offshore, wind could generate as much as 20 percent of domestic energy use.

To date, much of the wind development has been on private lands.? However, public onshore and offshore areas managed by the DOI have tremendous wind power potential. It is estimated that federal public lands in the West have 206 gigawatts of wind energy potential. The BLM has identified 20.6 million acres of high-quality wind locations on its lands in the 11 western states.? So far, the BLM has authorized 192 rights-of-ways for the use of public lands for wind energy production sites.? Of these, 25 authorizations have a total installed capacity of 327 MW.? Recently approved projects would increase capacity by 150 MW, and 15 projects currently being processed could add an additional 3,000 MW.??

Offshore wind development is the latest push for the DOI, with the Administration finalizing a framework for renewable energy production on the Outer Continental Shelf in late April. The framework "establishes a program to grant leases, easements, and rights-of-way for orderly, safe, and environmentally responsible renewable energy development activities, such as the siting and construction of offshore wind farms on the OCS."? DOI's Mineral Management Service (MMS) is overseeing the leasing process and, in late June, Salazar announced five exploratory leases for offshore wind off the coasts of New Jersey and Delaware, including the construction of meteorological towers. ?These are the first leases that the federal government has offered for offshore renewable energy testing and data collection.? These are limited leases and do not authorize commercial projects or provide the lessees with any option or preference for the commercial leasing.? Information on the potential impacts of offshore wind development is limited and the MMS has numerous ongoing studies to expand knowledge about the potential impact of expansive wind farms offshore.

Much has been made of the direct mortality of wildlife, particularly birds and bats, from wind towers, but often the greater impacts have to do with the habitat loss and fragmentation from development.? According to the American Wind Energy Association, the typical industrial wind farm will require approximately 60 acres per megawatt, although only 5 percent of this (3 acres/MW) is actually occupied by turbines, access roads and other equipment.? In addition, roads and transmission lines can impact birds, such as prairie chickens, and other wildlife species that are sensitive to habitat fragmentation.? Direct mortality has improved from early generations of wind farms due to better turbine design (taller towers with slower moving blades).? Nevertheless, national averages for avian mortality range from 2.3 to3.5 birds per MW.? Estimates of bat fatality from 19 different facilities in five different regions in the United States and a Canadian province ranged from 0.9 to 53.3 bats per MW.

Geothermal

Geothermal plants bring geothermal water?a hot, often salty, mineral-rich liquid withdrawn from a deep underground reservoir?to the surface to create steam that turns turbines to generate electrical power. It is considered by some as one of the more reliable forms of renewable energy because it does not depend on the sun shining or the wind blowing or seasonal water flows for power.? Geothermal is now the fourth largest domestic source of renewable energy power after hydroelectric, biomass and wind.? The United States is the world's largest producer of geothermal energy, with 3,000 MW of installed geothermal power plants operating in eight western states.? These plants generate an average of 15 billion kilowatt hours of power per year. Estimates by the Geothermal Energy Association suggest that the nine western states have the potential to provide more than 20 percent of national electricity needs.?

Federal lands are a potential hotbed for geothermal energy production.? The BLM has leasing authority for more than 249 million acres of federal land (100 million of which are national forest lands) with geothermal potential. The BLM currently manages 530 geothermal leases, with 58 leases producing about 1,275 MW of power.? The agency completed a Programmatic Environmental Impact Statement in late 2008 that opened 111 acres of BLM land and 79 acres of national forest for geothermal leasing.? It is estimated that an additional 5,540 MW of new generation capacity from 111 new geothermal plants will be in place by 2015.? An additional 6,600 MW from another 133 plants could be online by 2025.

Compared with other renewable energy sources and traditional fossil fuel extraction or fuel-burning power plants, geothermal has a smaller general impact.? There is a much smaller physical footprint, with the typical geothermal energy plant using less than a tenth of an acre per gigawatt hour.? Fifty percent of the geothermal water brought to the surface is emitted as steam and the remainder is pumped back into the underground reservoir to reheat. The process requires only 5 gallons of water per megawatt hour to function.? Potential impacts can occur from well blowouts, leaking pipes or wellheads, or overflow from well sumps, but the direct emissions from evaporated water into the air is limited.

Solar

At the end of 2008, the United States had just over 1,500 MW of installed solar power using the two primary technologies?photovoltaic (PV) panels and concentrating solar power.? PV systems, also known as solar cells, convert sunlight directly into electricity by knocking electrons loose from their atoms, causing them to flow through the material to produce electricity.? PV arrays, containing roughly 400 solar cells, are the panels that are most commonly seen.? Ten to 20 PV arrays can power an individual household, and hundreds of arrays can be linked together for utility or industrial applications. PV systems have become much more common for direct power generation where arrays are installed on or near where the power will be used. There currently are 1,100 MW of installed photovoltaic power in the US.

Concentrating solar power (CSP), which includes linear concentrators (parabolic troughs or Fresnel reflectors), a dish/engine system or a power tower, utilize mirrors to reflect the sun's energy to a thermal receiver that heats a fluid to generate steam or to power an engine generator. In order to generate power during cloudy or night periods, some utility systems are powered by fossil fuels, in particular natural gas, or they can be integrated with a thermal energy-storage system. Currently, there are 418 MW of installed utility-scale concentrating solar power in the United States.? Much of the anticipated utility-scale solar power is expected to use CSP because it has higher solar-to-electric conversion efficiency than do PV panels (currently PV arrays can convert into electricity only about 15 percent of the sunlight that hits the panels).? In addition, CSP is much cheaper than PVs, costing an average of 15 cents per kilowatt-hour over a plant's 30-year lifetime. According to the Solar Energy Industry Association, CSP projects totaling more than 6,000 MW are in the pipeline, with signed purchase power agreements.

Federal public lands in the Southwest have the greatest solar potential in the country.? The BLM manages 30 million acres with solar potential and has received more than 200 applications for utility-scale solar energy projects on 2.3 million acres of land.? In late June, the DOI announced several initiatives to fast-track solar development on federal lands (see related story in this issue of the ONB).? In addition, the Department of Energy has a goal of installing 1,000 MW of new concentrating solar power systems in the Southwest by 2010.? This level of deployment could help reduce CSP electricity costs to $0.07 per kilowatt-hour, which would allow it to compete effectively in the region's energy markets.

Concerns have arisen about the potential impacts of utility-scale solar power on sensitive desert lands where the greatest solar potential is.? One of the primary concerns is for habitat loss, inasmuch as recent applications for industrial CSP and PV systems averaging 8 to16 acres per MW.? The Ivanpah Project in the Mojave Desert has applied to use 6,720 acres for its 400 MW CSP plant and applications for two industrial PV plants also in the California deserts are for more than 14,000 acres each.? In addition, the land around the solar arrays often are scraped clean and leveled to reduce fire risk and to ensure that the mirrors are able to focus on their receiver.? Another concern with industrial solar power is the amount of water used in areas where water is scarce.? Water is used to wash mirrors to ensure their efficiency and to cool the systems to create steam for power generation.? For water-cooled systems, industrial systems could use as much as 27,000 gallons per megawatt hour (gal/MWh), although a new recirculating evaporative cooling process would use roughly 650 gal/MWh.? Dry-cooled systems use less than 10 percent of the water of evaporative cooled plants, however dry-cooled systems cost up to 10 percent more for consumers and reduces efficiency by 5 percent.? (jas)