NRG Energy evaluate conditions for growing switchgrass and high-biomass sorghum as renewable biomass fuels

(30/09/2009)

The U.S. Department of Energy has identified switchgrass as an ideal dedicated energy crop. As a perennial, once established, switchgrass requires little or no tilling and minimal nitrogen fertilizer and other crop inputs. It can grow over nine feet high with deep roots that can sequester carbon in the root biomass instead of releasing it into the atmosphere. Similarly, fast-growing high-biomass (non-grain) sorghum hybrids can reach 20 feet tall, while requiring much less water than conventional crops.

Harvested into bales like hay, energy grasses can be dried by the sun and then shredded into fine particles before being fed into the combustion chamber of a power plant. Since the carbon emitted from the grasses was previously absorbed from the atmosphere during the growing season, combusting the above-ground biomass is nearly carbon neutral. When the extensive root systems of perennial grasses are considered, power from biomass may even be considered carbon negative. Preliminary studies funded by the USDA demonstrated that each acre of switchgrass could sequester up to five tons of CO2-equivalent below ground each year.

NRG Energy, Inc. has begun a pilot project at the Company’s Big Cajun II electrical generating station to evaluate local conditions for growing switchgrass and high-biomass sorghum as renewable biomass fuels. These locally grown grasses will be further tested to determine their capacity to replace a portion of the coal at the plant and reduce its carbon intensity. The Big Cajun II project could lead to commercial-scale projects using biomass fuels to reduce carbon intensity from other coal plants.

Using improved seed varieties and growing techniques provided by Ceres, Inc., a leading developer and marketer of high-yield energy grasses, NRG is planting a test site on 20 acres of land at the Big Cajun II plant site. The switchgrass and high-biomass sorghum planted at the site was specifically chosen for use in Louisiana’s soil and climate and use as an energy crop and will be managed by a local grower.

“Biomass from locally grown energy grasses has the potential to be an important part of NRG’s multi-pronged approach to reduce our carbon intensity and can also be a source of economic development in rural communities,” said David Crane, NRG’s President and Chief Executive Officer. “In addition to nuclear, wind and solar, energy from biomass has the potential to help support an energy future that addresses global climate change in an environmentally and economically sustainable manner.”

The Big Cajun II test site will deliver data on yield (tons per acre) and other performance factors under local environmental conditions—a first step toward expanding the use of biomass fuels at NRG’s other existing coal facilities. A follow-on phase, expected to be conducted in 2010, will actually use the biomass as a partial fuel for electrical generation.

“Due to their low inputs, high yields and photosynthetic efficiency, energy grasses have the potential to provide scalable renewable baseload power to the grid at a scale not possible before. By working together with a leading company like NRG, we can determine the best ways to produce and deliver biomass as a source for biopower and create a model for the bioenergy industry and rural communities,” said Richard Hamilton, President and Chief Executive Officer of Ceres.

“By combining Louisiana’s rich environmental and energy resources, we can lay the groundwork to reduce our carbon intensity at our existing network of power plants,” said Jeff Baudier, president of NRG’s South Central region. “If successful, it will help develop a new and important biomass industry in the state that contributes renewable energy to our fuel mix.”

Related categories:  Biofuels and biomass   Eco-friendly Power generation