The best way to reduce greenhouse gas (GHG) emissions from coal-fired power plants in the U.S. is to replace plants that are more than 25 years old with facilities that coproduce electricity and synthetic fuels from coal and biomass while employing carbon capture and storage systems, according to Robert Williams, senior research scientist at the Princeton Environmental Institute.

In order to meet the goal of reducing U.S. emissions by 80 percent of 2005 levels by 2050, the nation needs to look mostly at coal power and transportation, Williams told the crowd of about 115 people during the Great Plains Institute conference on Nov. 2 at North Dakota State University in Fargo. The conference, titled The Future of Coal and Biomass in a Carbon-Constrained World: Technology and Policy Opportunities for the Midwest, featured several topics and hosted speakers from as far away as China. Tackling both coal power and transportation emissions simultaneously is the best option for meeting that 80 percent goal, Williams said. "That's a very daunting task," he said. "We need to make radical change and we need to get underway soon."
Retrofitting existing coal power plants with carbon capture and storage systems is one option, but Williams said it's extremely expensive and energy- and water-intensive. Completely replacing the systems not only leads to decarbonized energy, he said, but also enables coal to play a major role in the realization of zero GHG emissions in the production of synthetic transportation fuels. The replacement would mean a switch from combustion to gasification, which allows a relatively simple carbon dioxide removal, Williams said.

A coproduction system with carbon capture and storage, producing two-thirds synthetic fuels and one-third electricity, fired by 11 percent biomass, reduces system-wide GHG emissions by 50 percent, whereas a system with 38 percent biomass reduces emissions by 90 percent, he said.

Obstacles to making the switch remain, however, and are mainly institutional, not economic, Williams said. They include managing three commodity products and two feedstocks simultaneously, along with forming new strategic alliances that can overcome obstacles in the private sector and federal government.

Williams said new policies are also needed, including a strong, broad carbon mitigation policy that would protect biomass synfuels investors against oil price collapse risk. Carbon capture and storage early-action policies are important, he said, along with incentives for commercial-scale demonstrations between 2010 and 2020 and policies for widespread implementation thereafter. In addition, more policies supporting research and development of thermochemical bioenergy are needed, along with policies regarding the logistics of biomass supply.