Advanced Compressed Air Energy Storage: The Right Technology for the Renewable Energy Age

By Energy Storage and Power

The age of renewable energy is on its way. With the threat of global warming and dwindling natural resources at the forefront of the political and energy worlds, more and more states and utilities are turning toward large-scale renewable power projects like solar and wind farms. Both solar and wind power have the potential to be large, crucial components in the search for climate change solutions.

But like any real-world solution, solar and wind power raise their own set of issues. One of the most difficult issues is that both of these sources are intermittent. For example, the wind is often strongest at night – producing a lot of electricity at a time when the grid requires the least. An effective way to store the energy produced by solar and wind power for use when it is most needed will be a key factor in improving the economic viability of clean, renewable energy sources.

An energy storage solution

Stepping in with a solution is Energy Storage and Power (ES&P) and its second generation of compressed air energy storage (CAES2) technology. CAES2 builds on a number of environmental and economic improvements made by chief technical officer Dr. Michael Nakhamkin on his original design of the first generation CAES plant in McIntosh, Alabama.
CAES technology stores off-peak energy, in the form of compressed air in an underground reservoir, and releases this energy during peak hours. CAES can be used for load management of intermittent renewable energy resources or as a stand-alone intermediate generation source. CAES technology is suitable for a wide range of renewable energy developers, independent power producers, electric utility companies and transmission owners.

“Compressed air will make clean renewable energy more accessible to the marketplace in the not-too-distant future,” explains ES&P CEO Roy Daniel. “Energy storage and grid regulation from CAES fill in the missing piece of the puzzle for a green, affordable and reliable 21st century electricity grid.”

Compressed air storage uses off-peak electricity generated by any number of sources – a wind farm, for example – to compress air for storage in an underground reservoir. When electricity is needed, the stored air can be released from the reservoir, heated by a gas-fired burner and run through a turbine that drives an electric generator, essentially completing the transformation back to usable electricity.

New, improved technology

Second-generation CAES (CAES2) has its origins in Dr. Nakhamkin’s design of the U.S.’s only CAES plant almost 20 years ago in McIntosh, Alabama. But the technology has come a long way where it now can enable renewable energy’s development and expansion.
“We have learned a lot about the logistics of compressed air energy storage, and I believe the time is right technically, environmentally and economically for a large-scale deployment of ES&P’s CAES technology,” said Nakhamkin. “The technology has evolved to the point where it can be critical to helping this nation meet its growing energy needs while decreasing carbon emissions from the electricity sector.”

When CAES technology produces electricity, the compressed air being released needs to be heated in order to power the expansion turbine that drives the electric generator. The new CAES plants use a built-in air expander that makes use of waste heat from a turbine within the system, eliminating the need for a separate burner. This advancement greatly reduces the natural gas needed for the process, making second-generation CAES plants much more economically and environmentally sound by lowering costs and emissions. "It is a simple new concept, a proven standard using on-the-shelf components," Nakhamkin said.

Scalable solutions for projects of any size

Studies by the Electric Power Research Institute (EPRI) indicate that up to 80% of the United States has geology that would be suitable for an underground CAES reservoir. One of ES&P’s large-scale, 300 MW CAES plants will require roughly 22 million cubic feet of space – just about a third of the size of a football stadium. A CAES reservoir at full capacity could produce enough electricity to power around 200,000 homes for about 8 hours. EPRI believes there could be 20 to 50 CAES plants of different sizes in operation by 2020, supporting the rapidly emerging renewable energy market in America.

ES&P also plans to market smaller versions of the CAES technology that will utilize above-ground storage canisters in place of the below-ground reservoirs. Ideally, these smaller systems would provide optimal, cost-effective alternatives to utility-scale batteries and other electronic systems of energy storage. These CAES systems would offer utilities a low-cost, low-carbon option for reinforcing their transmission systems in the case of any type of outage. The technology can be sized to the specifications and needs of the utility.

Making renewables reliable

The issue of energy storage is most crucial to the wind power industry. Wind farms – both on land and offshore – are currently seen as one of the U.S.’s best paths towards drastically reducing greenhouse gas emissions in the energy industry. However, wind is intermittent in nature and can’t be relied on as a constant source of energy. Wind energy output is often strongest at night. This leads to an excess of electricity being produced when it is not needed and a system that is not reliable enough to be the primary source of energy during peak usage periods. This is where, in effect, CAES can come to the rescue. Utility-scale CAES plants can be paired with many of the country’s emerging wind farm projects to make wind power a more reliable source of green energy.

“CAES units can manage wind output to create a highly valuable, firm, dispatchable product,”  Daniel explains. “A CAES unit protects the wind farm from transmission congestion.” This transmission congestion problem can also become an economic burden on wind companies. If a wind farm produces most of its energy during off-peak hours, when demand is low, the energy will be sold at off-peak prices significantly lower than the prices during peak usage hours. With the gap between peak and off-peak energy prices widening, many companies view wind and other renewables as risky investments to make in a shaky economic climate. ES&P sees a utility-scale compressed air storage solution as a form of insurance against some of the financial risk of renewable energy projects.

A fit for all clean energy

Arshad Mansoor, EPRI’s vice president of power delivery and utilization, believes that CAES plants can be effectively used to supplement other types of low-carbon and carbon-free electric generation, such as nuclear power.

“Nuclear is an inherently stable source of power, so stable that we don’t want to ramp it up and down,” Mansoor explains in The Energy Daily. “Nuclear will need storage at night, when demand is low, and we really are looking at hundreds of megawatts of storage to meet that need.”

“We asked the questions, ‘If we need bulk storage in our portfolio in the next five to ten-year timeframe, what technologies are available?’ There are lots of options, but we need options that are cost effective and deployable in that time frame…The only answer we were left with is compressed air.”

In the world’s current climate, the future of energy needs to be cost efficient and environmentally sound. With compressed air energy storage, renewable energy can realize its full potential to the benefit of the economy and environment. Energy Storage & Power is ready to offer its advanced CAES technology as a clean, efficient energy storage option to speed the arrival of the renewable energy age and make America’s green energy future a reality.

Contact details:
Roy Daniel, Chief Executive Officer
T: (866) 941-CAES (2237), E: info@energystorageandpower.com
www.energystorageandpower.com