Limiting Coal Targets to Fight Climate Change

The quickest and most effective way to deal with emissions from new coal power plants might be to capture perhaps 60 percent of the gas, and not press for more ambitious targets, according to an analysis presented today at the 9th International Conference on Greenhouse Gas Control Technologies, in Washington, DC.

Howard Herzog, a principal research engineer at MIT (where he manages an industry consortium on carbon capture and storage), explained to me that this route might be akin to the progression we are now seeing in automobiles: from gasoline-powered cars to hybrid versions, en route to a future full of plug-in hybrid or full-electric cars charged from an electric grid that conveys mainly clean renewable power.

Given that right now none of the 600 U.S. coal power plants–or virtually any other source of greenhouse gas–captures and sequesters CO₂, you have to start somewhere, he said. “We are trying to look at it from an energy security viewpoint, an economic viewpoint, and a carbon-capture viewpoint,” said Herzog, who coauthored the analysis with Ashleigh Hildebrand, a graduate student in chemical engineering and technology policy.

Herzog went on to explain that coal is a secure American resource that doesn’t require importing liquefied natural gas. Partial capture would be cheaper than full capture (which would require extra processing steps). Depending on the type of plant, reducing coal’s CO₂ emissions by between 45 and 60 percent would mean that it emits as much CO₂ as a natural-gas power plant. And because the partial-emission version would be more economical, it could mean faster implementation, which would, in turn, help prove the feasibility of capturing and burying CO₂ (in various underground reservoirs, for the most part) on a massive scale. Research is continuing into the optimal capture levels on both coal-burning and coal-gasification designs, Herzog added.

The conference is mainly a technical affair, full of presentations on the suitability of various geologic formations for CO₂ storage, how to do seismic analysis of CO₂ reservoirs, and the experience of various pilot projects. Ruben Juanes, an assistant professor of civil and environmental engineering at MIT, described his new model for calculating how much CO₂ a geologic formation can safely hold, for example.

But the critical importance of these various geologic and modeling studies was driven home in a keynote by Susan Solomon, an atmospheric chemist at the National Oceanographic and Atmospheric Administration, who gave a primer on climate change over lunch. It wasn’t new ground, but it’s always good to be reminded of some basics, such as “We have made CO₂ [concentrations in the atmosphere] higher than it has been in more than half a million years, and that is the predominant cause of today’s global warming.”

Solomon reminded everyone that if we are to avert the worst effects of global warming and climate change–the droughts, the species extinctions, the water shortages, the catastrophic sea-level rise–we must act now and essentially dial our emissions back to something close to zero over the next few decades. Part of that will mean burying CO₂ rather than spewing it into the atmosphere. Unfortunately, we were reminded of these sobering realities while being served steak–that most fuel-intensive source of protein–in a banquet hall lit by hundreds of incandescent lightbulbs.