Natural gas will play a leading role in reducing
greenhouse-gas emissions over the next several decades, largely
by replacing older, inefficient coal plants with highly
efficient combined-cycle gas generation. Thats the
conclusion reached by a comprehensive study of the future of
natural gas conducted by an MIT study group comprised of 30 MIT
faculty members, researchers and graduate students.
The two-year study, managed by the MIT Energy Initiative
(MITEI), examined the scale of US natural gas reserves and the
potential of this fuel to reduce greenhouse-gas emissions. 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 fuels 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 gasespecially in electric power
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
Key findings. The US 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. Globally,
baseline estimates show that recoverable gas resources probably
amount to 16,200 trillion cf, enough to last over 160 years at
current global consumption rates. In the US, unconventional gas
resources are rapidly overtaking conventional resources as the
primary source of gas production. The US currently consumes
around 22 trillion cf per year and has a gas resource base now
thought to exceed 2,000 trillion cf.
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).
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; and surface and local community disturbance,
due to drilling and fracturing activities.
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 CO2 emissions by 50% 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
The overbuilding of natural gas combined cycle (NGCC) plants
starting in the mid-1990s presents a significant opportunity
for near term reductions in CO2 emissions from the
power sector. The current fleet of NGCC units has an average
capacity factor of 41%, relative to a design capacity factor of
up to 85%. However, with no carbon constraints, coal generation
is generally dispatched to meet demand before NGCC generation
because of its lower fuel price.
Modeling of the ERCOT region (largely Texas) suggests that
CO2 emissions could be reduced by as much as 22%
with no additional capital investment and without impacting
system reliability by requiring a dispatch
order that favors NGCC generation over inefficient coal
generation; preliminary modeling suggests that nationwide
CO2 emissions would be reduced by over
10%. At the same time, this would also reduce air pollutants
such as oxides of sulfur and nitrogen.