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Tuesday, September 23, 2014

Study - use natgas to shut down coal, but don't build new fleet of natgas power plants - UPDATED

A new study published in The Electricity Journal finds that, from the standpoint of tackling global climate disruption, while burning natural gas for electricity offers a 50 percent reduction in GHG emissions over coal, building whole new fleets of natgas-fired power plants will exacerbate the climate problem.

Natural Gas versus Coal: Is Natural Gas Better for the Climate, according to an issue brief released in conjunction with the study, finds that with methane leakage at every stage of the natural-gas lifecycle:  
under the best of circumstances, natural gas-fired electric power plants can only make a modest dent on abating climate change—and, if developed poorly, with serious methane leaks, or if used to displace energy efficiency or renewable energy, natural gas could instead seriously contribute to the problem. Over a timeframe of 100 years, natural gas with careful leak control offers some reduction in greenhouse gas (GHG) emissions. However, these reductions are not large enough for natural gas to play an expanded role in efforts to manage GHG emissions. 
Not without requiring CCS/CCUS for natgas plants

The study goes on:
It makes sense to use excess capacity from existing natural gas plants to help shut down the United States’ aging fleet of coal plants. But investment in many more large natural gas power plants would not be sensible. New advanced gas turbines that are flexible – able to ramp up and down quickly while maintaining high efficiency – do have an important role going forward to help integrate variable renewable electricity sources like wind and solar power. But such plants are just one option in a portfolio of strategies available to handle renewables variability. A principal driver of natural gas’s contribution to climate change is leaking methane. It is important, then, that the federal government and the states should put in place stronger regulations to reduce methane leakage to close to zero—and limit other environmental impacts.
Stronger regulations on natural gas development are a must.  To win the climate battle, so, too, are energy choices that are driven by strong policies and not left to the unguided free market.

September 24, 2014 update:  Here is the full paper.  Friends - who are researchers at at Carnegie Mellon University University - have pointed out that the authors' brief - quoted in my post - uses much stronger language than the paper itself. The conclusion in the full paper is still relevant:
Natural gas proponents present it as the logical next step down the staircase of environmentally destructive energy...(M)ore than incremental progress is needed when thinking about the future of the U.S. electricity system. Moreover, while natural gas is often hailed as a cleaner alternative, the reality is more complex. The research described in this article illustrates that when there are opportunities to substitute for coal power on the margin, looking at GHG emissions alone, it likely makes sense under a wide range of circumstances. This is even before the criteria pollutant advantage of natural gas is considered. Nonetheless, it is important to emphasize the difference between running current plants more intensively and building out further infrastructure. If the case for new investment in natural gas is motivated in part by GHG mitigation then it is necessary to calculate cost per ton abated and to compare this to other alternative mitigation investments. Significant leakage in the methane system may not completely eliminate the GHG benefit of new gas over coal, but it will erode the relative climate benefit of natural gas as a GHG mitigation option.
Moreover, there is an urgent need to reduce both short-term and long-term GHGs. It is not enough that gas substitution for coal does no harm in the very long run. We need to be minimizing methane emissions including leakage from the natural gas supply in order to make short-term progress in averting increasingly severe impacts from climate change. Measurable impacts and economic damage are already occurring.
My thanks to Costa Samaras and Subu Subramanian for reading, for these insights, and for educating me.


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