Shale Gas
By David
Rotman
MIT Technology Review, November/December 2009
Edited by Andy Ross
Vast deposits of black shale stretch from New York to Alabama. The Marcellus
shale holds enough natural gas to supply the United States for decades. Natural
gas burns much cleaner than coal, and burning natural gas in cars and trucks
could reduce U.S. reliance on foreign oil.
The shale deposits stretch for thousands of square kilometers and are estimated
to contain over 17 trillion cubic meters of recoverable gas. The United States
consumes about 650 billion cu m of natural gas a year. With potential gas
resources of up to 60 trillion cu m, the country has enough gas for many
decades.
Once a hole is drilled, engineers will use a procedure called hydrofracturing to
force millions of liters of water down the well and into the shale formation at
high pressure. The water is mixed with fine sand and chemical additives and
enlarges tiny cracks in the deposits. If all goes well, the natural gas flows
into the pipe when the water is pumped out.
Coal-fired plants generate about 50 percent of the electricity used in the
United States, but they produce 82 percent of the power industry's carbon
dioxide emissions. Burning natural gas produces roughly half as much carbon
dioxide as coal. And existing gas-fired power plants have excess capacity, since
they are generally used as backup to coal plants at times of peak demand.
Technically, it's easy to substitute natural gas for gasoline or diesel fuel in
cars and trucks. But this won't make much difference. Although a natural-gas car
emits about 25 percent less carbon dioxide than a gasoline-powered vehicle,
running all the country's vehicles on natural gas would reduce overall emissions
by just 8 percent.
Drilling for shale gas could provide another environmental benefit. Fossil-fuel
power plants will eventually need to capture and sequester their carbon dioxide
emissions. That means finding a safe, economical way to store carbon dioxide so
that it cannot leak out. Shale deposits might provide a solution.
Researchers are studying a process that could trap carbon dioxide in depleted
natural-gas wells. Methane in shale is adsorbed in the deposits. Tests show that
carbon dioxide binds to these materials more strongly than methane does. Carbon
dioxide pumped into almost-depleted wells could displace the adsorbed methane.
If it works, the process would free extra gas in these wells while sequestering
the carbon dioxide underground.
Some experts doubt the wisdom of rapidly expanding the market for natural gas.
The experience of Great Britain in the last twenty years provides a sobering
example. The country sat beside an enormous deposit of natural gas in the North
Sea. Government and industry made a "dash for gas" by introducing gas-burning
power plants. The country's coal industry all but disappeared, and nuclear power
was largely neglected. Now the UK imports much of the natural gas it needs for
electricity generation.
The availability of vast natural-gas resources has transformed the U.S. energy
situation. The natural gas buys time to reduce greenhouse gas emissions before
more innovative technologies are developed and deployed.
Gas For Decades
By
Ambrose Evans-Pritchard
The Telegraph, October 11, 2009
Edited by Andy Ross
24th World Gas Conference,
Buenos Aires, October 2009
Advances in technology for extracting gas from
shale and methane beds have altered the global energy balance faster than
expected. BP chief executive Tony Hayward said proven natural gas reserves
around the world have risen to 1.2 trillion barrels of oil equivalent. The U.S.
Department of Energy expects shale to meet half of U.S. gas demand within 20
years. Projects are starting in France and Poland. Exploration is under way in
Australia, India, and China. The United States may even find that gas, wind, and
solar power, plus a smart grid and electric cars, return the country to energy
self-sufficiency. Shale gas is messy to extract and not very green. But the
Sierra Club is backing
it.
AR This gas can take us a big step nearer to the promised hydrogen economy.
