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MIT Study Finds Significant Potential to Displace Coal, Reducing Greenhouse Gas Emissions

Natural Gas

A study group comprising of 30 MIT faculty members, researchers, and graduate students has come up with a summarized 83-page report titled “The Future of Natural Gas” with key findings of their research which was presented to law-makers and senior administration officials this week in Washington.

The two-year study, managed by the MIT Energy Initiative (MITEI), examined the scale of U.S. natural gas reserves and the potential of this fuel to reduce greenhouse-gas emissions. Based on the work of the multi-disciplinary team, with advice from a board of 16 leaders from industry, government and environmental groups, the report examines the future of natural gas through 2050 from the perspectives of technology, economics, politics, national security and the environment. 

The report includes a set of specific proposals for legislative and regulatory policies, as well as recommendations for actions that the energy industry can pursue on its own, to maximize the fuel’s impact on mitigating greenhouse gas. The study also examined ways to control the environmental impacts that could result from a significant expansion in the production and use of natural gas – especially in electric power production.

“Much has been said about natural gas as a bridge to a low-carbon future, with little underlying analysis to back up this contention.  The analysis in this study provides the confirmation – natural gas truly is a bridge to a low-carbon future,” said MITEI Director Ernest J. Moniz in introducing the report. 

Moniz further noted, “In the very long run, very tight carbon constraints will likely phase out natural gas power generation in favor of zero-carbon or extremely low-carbon energy sources such as renewables, nuclear power or natural gas and coal with carbon capture and storage.  For the next several decades, however, natural gas will play a crucial role in enabling very substantial reductions in carbon emissions.”

Two major factors that can make a significant difference in the near term in reducing carbon emissions are using less energy and using gas instead of coal – especially by replacing the oldest, least-efficient coal plants with the most-efficient modern combined-cycle gas plants, said Moniz, who chaired the study, along with co-chairs Henry Jacoby, Professor of Management, and Tony Meggs, MITEI Visiting Engineer. Professor Jacoby is co-director of the MIT Joint Program on the Science and Policy of Global Change.

The study found that there are significant global supplies of conventional gas. How much of this gas gets produced and used, and the extent of its impact on greenhouse gas reductions, depends critically on some key political and regulatory decisions. 

In the United States, for example, there is a substantial amount of low-hanging fruit available by displacing inefficient power generation with more efficient, lower CO2emitting gas plants. “That kind of substitution alone,” Moniz said, “reduces those carbon emissions by a factor of three. It does, however, raise complicated regulatory and political issues that will have to be resolved to take advantage of this potential.”

Some of the study’s key findings:

1. The United States has a significant natural gas resource base, enough to equal about 92 years’ worth at present domestic consumption rates. Much of this is from unconventional sources, including gas shales. While there is substantial uncertainty surrounding the producibility of this gas, there is a significant amount of shale gas that can be affordably produced. 

Globally, baseline estimates show that recoverable gas resources probably amount to 16,200 trillion cubic feet (Tcf) – enough to last over 160 years at current global consumption rates.  Further, this global resource figure, excluding the U.S. and Canada, does not include any unconventional gas resources, which are largely uncharacterized in the rest of the world. Russia, the Middle East, and the U.S. have the highest concentration of global gas reserves.  

In the U.S., unconventional gas resources are rapidly overtaking conventional resources as the primary source of gas production. The U.S. currently consumes around 22 Tcf per year and has a gas resource base now thought to exceed 2,000 Tcf. 

In order to bring about the kind of significant expansion in the use of natural gas identified in this study, substantial additions to the existing processing, delivery and storage facilities will be required in order to handle greater amounts and the changing patterns of distribution (such as the delivery of gas from newly developed sources in the Midwest and Northeast).

2. Environmental issues associated with producing unconventional gas resources are manageable but challenging. Risks include: Shallow freshwater aquifer contamination with fracture fluids; surface water contamination by returned fracture fluids; excessive demand on local water supply from fracturing operations; and surface and local community disturbance, due to drilling and fracturing activities.

3. Natural-gas consumption will increase dramatically and will largely displace coal in the power generation sector by 2050 (the time horizon of the study) under a modeling scenario where, through carbon emissions pricing, industrialized nations reduce CO2emissions by 50 percent by 2050,  and large emerging economies, e.g., China, India and Brazil reduce CO2 emissions by 50 percent by 2070. This assumes incremental reductions in the current price structures of the alternatives, including renewables, nuclear and carbon capture and sequestration.  

4. The introduction of large intermittent power generation from, for example, wind and solar, will have specific short and long term effects on the mix of generation technologies. The short term effects (meaning daily dispatch patterns of various fuels) of large amounts of wind generation for example will reduce gas generation significantly and could force baseload coal plants to cycle, an outcome which is highly undesirable from an operational perspective.  

In the longer term, the reliability of a system in which renewables assume a baseload role in power generation will require additional flexible natural gas peaking capacity, although this capacity may be utilized for only short periods of the time. Renewables as baseload power, firmed by natural gas generation, will require new regulatory structures to ensure reliability of the system and incentivize the building of flexible gas capacity.