CALGARY --
A technology used in ancient Greece to power clocks and fire a cannon
is undergoing a revival as the world searches for better ways to store
energy from wind turbines and solar panels. Compressed air, already used to power carnival rides, jackhammers and medical equipment, joins the crowded field of innovations chasing what may be a $21.5 billion market in 2024. Contenders include Elon Musk, chairman of Tesla Motors Inc., who this month unveiled a suite of batteries to store electricity for homes, businesses and utilities.
While Tesla plans to begin delivering its rechargeable lithium-ion model in late summer, compressed air storage systems,
or CAES, may have an edge. The technology can be used to store large
amounts of power for weeks at less than the cost of batteries. “You need bulk storage to support all the renewables
and CAES is pretty much the only technology to do that,” said Jim Heid,
vice president at Dresser-Rand Group Inc., a supplier of compressed air
products. “It’s a worldwide phenomenon because of all the intermittent
renewables coming online.”
The mechanics are simple. Start with electricity from
wind turbines and solar panels to run compressors that fill man-made
caverns also used for natural gas storage. When the pressurized air is
released, it drives turbines that provide clean power when the sun
doesn’t shine and the wind doesn’t blow.
In less than a decade, annual investment in compressed
air will be almost $5 billion, according to Navigant Research. That
will support more than 11 gigawatts of installed capacity and help
renewable power developers match demand with supply. Competition is stiff.
Along with batteries, developers are using everything from vats of
molten salt to rooftop tanks filled with ice to store energy, a market
Navigant sees expanding about 35-fold by 2024 from $605.8 million this
year.
Improvements Needed
Even supporters acknowledge that air storage needs to
improve. The systems currently return only about 60 percent of the power
used to fill caverns, according to Dresser-Rand. “When you put in one unit of energy, you want to get
one unit out,” said Sam Shelton, senior fellow at the Strategic Energy
Institute at the Georgia Institute of Technology. “Air is not very dense
so compression storage is low efficiency. It’s all economics.”
Advancements in technology will boost efficiency and
eliminate the need to heat the pressurized air with natural gas,
reducing carbon dioxide emissions. Developers are improving above-ground
vessels for smaller-scale applications. “Overall it’s a market that has a couple of niches,”
said Brian Warshay, an analyst with Bloomberg New Energy Finance in New
York. “A lot depends on the location and the proximity to demand.” Two years ago, California regulators asked the state’s
three biggest utilities to add 1.33 gigawatts of energy-storage
capacity by 2020 -- about 20 percent more than currently exists in the
world, excluding pumped hydropower systems.
Rooftop Ice
Spain’s Abengoa SA is developing a solar-thermal project
in California that will incorporate power storage. Ice Energy Holdings
Inc., a Santa Barbara, California-based company, is pioneering a storage
method using rooftop ice to provide cooling during the day. The Greek inventor Ctesibius wrote studies on the
science of compressed air in the third century BC. The technology was
used in an alarm clock, a cannon that shot arrows and to open the gates
at the Temple of Alexandria.
Thanks to its scale, compressed air storage today
offers a solution to a challenge facing grid operators -- how to store
wind power at night when demand for electricity slumps, and solar power
for cloudy days.
Compressed air can store hundreds of megawatt hours of
electricity for weeks at a time. Batteries are useful for smaller
volumes for shorter periods, said Rocco Vita, director of emerging
technology at pipeline company Enbridge Inc., which operates solar and
wind farms across North America.
Texas Wind
Chamisa Energy, based in Santa Fe, New Mexico, is
seeking to raise about $400 million to build a compressed air project in
the Texas Panhandle that can store wind energy at night and release it
when turbines are still. “We’re surrounded by some of the best wind in the U.S.
and the wind often blows in the off-peak,” said Alissa Oppenheimer,
managing director at Chamisa. “There are numerous times of the day when
the price of wind is negative.”
Investors, who may not understand the advantages of
the technology or are concerned that air storage systems are
inefficient, have been slow to commit, Oppenheimer said. Dresser-Rand built one of the world’s two commercial
compressed air systems in Alabama in 1991 and is currently working on
other projects in Texas, said Heid. In Alabama, Power South Energy
Cooperative’s 110-megawatt system stores enough energy from nearby power
plants to power 110,000 homes. The world’s first commercial application
of the technology was in Germany in 1978 with a 290-megawatt plant.
Surplus Energy
In Canada, Ontario’s grid operator wants to add 16
megawatts of storage, including CAES, to cope with a supply surge from
wind turbines and solar panels. NRStor Inc., which is bidding for the
contract, expects the efficiency and cost of air storage to improve. Were Ontario to add 1,000 megawatts of compressed air
storage, consumers would save C$8 billion ($6.6 billion) over 20 years,
said NRStor Chief Executive Officer Annette Verschuren. With the system
she’s proposing, stored air could turn turbines for as long as 300
hours.
“Ontario has really built up a lot of renewable energy
and is building up a lot more surplus energy,” Verschuren said. “We
would capture the night stuff, capture the weekend stuff and put the
energy on the grid during daytime.” NRStor sees the price of compressed air systems
falling fall to one-tenth that of the expected $350 a kilowatt hour cost
of battery storage in 2022, said Verschuren. She declined to say how
much the Ontario project will cost.
Copyright 2015 Bloomberg
http://www.renewableenergyworld.com/rea/news/article/2015/05/ancient-greek-energy-storage-technology-challenges-teslas-batteries
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