Synopsis A new paper by a leading group of scientists, engineers, and architects argues that the U.S. could eliminate CO 2 emissions from coal in 20 years.

The U.S. could end its global warming emissions from coal in two decades by embracing a collection of proven and promising technologies, according to a new ES&T paper (Environ. Sci. Technol. DOI 10.1021/es903884a). Climate scientists James Hansen and Pushker Kharecha, together with Charles Kutscher of the National Renewable Energy Laboratory (NREL) and noted architect Edward Mazria, say their paper targets coal because it is the energy source that is most responsible for accumulated fossil fuel CO 2 in today’s atmosphere.

Kharecha and Hansen, both of the NASA Goddard Institute for Space Studies and the Columbia University Earth Institute, and their coauthors argue that fast action is demanded by recent revelations in the field of climate science. For example, a draft of the Fifth U.S. Climate Action Report released in mid-April says that current effects of climate change include water cycle disruptions, vanishing mountain glaciers, and extreme weather events. In the new paper, the scientists write, “The ‘safe’ long-term level of atmospheric greenhouse gases is much lower than has been supposed, [and CO 2 concentrations are] already into the dangerous zone.”

The ES&T paper is both noteworthy and valuable for conveying the urgency of changing the mix of technologies used to produce U.S. electricity, says Robert N. Schock, the World Energy Council’s director of studies. Shock played a key role in developing the climate change mitigation technology recommendations for the Intergovernmental Panel on Climate Change (IPCC). He says that the collection of energy efficiency, renewable, and nuclear power technologies discussed in the new paper are consistent with the IPCC’s recommendations.

The mix of technologies is also very similar to the assortment that the electric power industry is investigating to meet future generation needs based on expected regulatory drivers to reduce greenhouse gas emissions, says Revis James, director of the Energy Technology Assessment Center run by the nonprofit Electric Power Research Institute (EPRI). He adds that the paper and EPRI’s research agree that “successful decarbonization will require a fairly diverse set of technologies.”

That said, James says that he thinks it is unlikely that all of the technologies discussed in the article will be in place by 2030. He also points out that EPRI research indicates that coal, if teamed with carbon capture and sequestration (CCS), could remain important in the future. “Obviously, coal is the number one technology that we have to decarbonize. Fifty percent of [U.S.] electricity generation is from coal, and the bulk of electricity emissions are the result of coal,” he says.

“We believe our recommendations can be implemented fairly rapidly,” says Kharecha, the paper’s corresponding author. “The key missing ingredient is political will, not the technical potential of the various options” discussed in the paper, he says.

Kharecha and his colleagues argue that the best way to move the U.S. toward the scenario they envision would be to end fossil fuel subsidies and levy a substantial fee on carbon emissions.

Kharecha stresses that the majority of the technologies discussed in the paper have been demonstrated to be capable of producing utility-scale power. One that has not yet met this criterion is enhanced geothermal systems, which according to the paper, could vastly expand the already very large national geothermal resource base. However, the Obama Administration recently announced $80 million in funding for the technology.

A major advantage of geothermal power over many other renewable sources is its ability to reliably produce the minimum “base-load” of power that utility customers require.

Biomass can also be used to produce base-load power. Kharecha and colleagues estimate that by 2025, biomass power from forestry, agriculture, and urban and industrial waste could produce approximately half of the power now generated by coal-fired plants. “Biomass power also offers an important option that other renewables do not: the potential to incorporate [CCS], thereby making biomass power substantially carbon-negative,” the paper points out. The authors recommend using waste products such as agricultural residue to avoid indirectly producing what they term “carbon-positive land use changes.”

The paper recommends increasing the energy efficiency of homes and buildings because they consume almost 75% of the electricity generated in the U.S. It also foresees important roles for wind and solar, and advises that the national power grid be upgraded to enable much larger deployment of renewable power. The nuclear power technologies that the report recommends as warranting development include two of the “next-generation” reactors based on closed fuel cycles that “breed” new fuel during their operation.

“We believe climate change is a crisis of such great proportions that we can ill afford to take any potential energy supply contributor off the table,” says coauthor Kutscher, principle engineer for NREL’s Electricity, Resources and Building Systems Integration group.

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