caverns

A giant underground battery

February 5, 2024 By EarthWise Leave a Comment

Two up-and-coming energy technologies are coming together near a tiny town in central Utah. Outside of the town of Delta, population 3,600, two caverns, each as deep as the Empire State Building, are being created from an underground salt formation to be used to store hydrogen gas. The gas will be used as a fuel in a new electricity generation plant.

The plant will replace an aging local coal-fired power plant. The new plant will burn a mixture of natural gas and hydrogen – green hydrogen produced without emitting greenhouse gases. To produce the hydrogen, the facility will operate 40 giant electrolyzers that will use excess solar and wind power generated at times of low demand to split water molecules into hydrogen and oxygen.

The caverns were created by a process called solution mining in which high-pressure water is pumped down into salt deposits that are dissolved. The resulting caverns are 200 feet in diameter and 1,200 deep and lie 3,000 to 4,000 feet below the surface. Hydrogen cannot escape through the thick salt layers.

The amount of energy that can be stored in the form of hydrogen fuel in these caverns is massive – far more than all the battery storage installed in the U.S. to date. Chevron has a majority stake in one of the projects and will supply the natural gas. The facility is expected to go online in 2025.

While this will produce far fewer emissions than existing coal plants, it is not carbon-free. Currently, turbine technology cannot operate with pure hydrogen fuel. The Delta plant will run on only 30% hydrogen. The hope is that turbine technology will improve in the future and permit operation on pure hydrogen.

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A Huge Underground Battery Is Coming to a Tiny Utah Town

Photo, posted September 9, 2013, courtesy of Scott via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Pulling Carbon Dioxide Out Of Seawater | Earth Wise

April 17, 2023 By EarthWise Leave a Comment

The world’s largest sink for carbon dioxide from the atmosphere is the ocean. The world’s oceans soak up 30-40% of all the gas produced by human activities. Dissolving carbon dioxide in water produces carbonic acid. This is the reason that oceans are becoming increasingly acidic, which is causing serious damage to ocean ecosystems.

There are many efforts underway aimed at directly removing carbon dioxide from the air as a way to mitigate the effects of ongoing emissions. But another possibility is to remove CO2 directly from ocean water. Existing methods for doing it involve the use of expensive membranes and complex chemicals. The economics of such methods are quite unfavorable.

Recently, a team of researchers at MIT has identified what they claim is a truly efficient and inexpensive removal mechanism. It involves a reversible process based on membrane-free electrochemical cells. Electrodes in the cells release protons that are introduced to seawater which drive the release of carbon dioxide dissolved in the water. The carbon dioxide can be collected and the processed water ends up being alkaline.

Running this process at a site that is already collecting seawater – such as at a desalination plant – would be an effective way to collect carbon dioxide as well as help mitigate ocean acidification.

Once the carbon dioxide is removed from the water, it still needs to be disposed of, just as is the case for other carbon removal processes. It could be turned into useful chemicals or it could be stored in underground caverns. But this approach is fairly unique in that the carbon dioxide has already been captured by the ocean. The issue remains what to do with it.

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How to pull carbon dioxide out of seawater

Photo, posted January 19, 2016, courtesy of Judy Dean via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Turning Carbon Into Stone | Earth Wise

January 31, 2023 By EarthWise Leave a Comment

A start-up company in Oman called 44.01 was recently awarded a $1.2 million Earthshot Prize by Prince William of the U.K. The company, whose name corresponds to the molecular weight of carbon dioxide, is working on speeding up natural chemical reactions that take carbon from the air and lock it into solid mineral form.

The company’s location in Oman is no random occurrence. The mountains of northern Oman and along the coast of the United Arab Emirates are the site of a huge block of oceanic crust and upper mantle that was thrust upward some 96 million years ago. The tilted mass of rock is over 200 miles long and is the largest surface exposure of the Earth’s mantle in the world.

This type of rock, called peridotite, is rich in olivine and pyroxene, which react with water and carbon dioxide to form calcium-based minerals like serpentine and calcite that permanently lock in carbon. Other kinds of rock also are capable of carbon-storing mineralization, but this mantle rock is the most effective for the purpose. It only exists at the Earth’s surface in a few places, including Papua New Guinea and some spots in California and Oregon.

The 44.1 company is planning to use solar-powered direct air capture devices to remove CO₂ from the air, use it to produce carbonated water, and inject the water into the reactive rocks. The company will operate a couple of pilot systems during 2023. Ultimately, the company believes it can scale up the process to be able to permanently sequester as much as a billion tons of CO₂ a year by the year 2040 without needing to inject the gas into deep caverns or find other places to store it.

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With Major Prize, a Project to Turn Carbon Emissions to Stone Gains Momentum

Photo, posted August 10, 2018, courtesy of JM McBeth via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Compressed Air Energy Storage

October 23, 2019 By EarthWise Leave a Comment

The increasing use of solar and wind power has created a growing need for technology to store up the energy they generate for use when it is most needed.

Historically, pumped hydropower has provided the largest amount of storage capacity, but it is limited to only certain geographic locations. Battery energy storage has been growing rapidly, with the technology becoming better and cheaper over time. But there are various other ways to store energy that have potential and may well find their place in the changing energy infrastructure.

One of these is compressed air energy storage, which has been around for more than a century. It has been used as a backup method for restarting power plants. But to date, the economic viability of using it at a large scale has been lacking.

A Canadian startup company called Hydrostor is developing compressed air energy storage technology that it believes can be used on a utility scale.

The way it works is excess renewable energy is used to run compressors that compress air. Compressing the air heats it up and the heat is captured and stored in insulated hot water tanks. The compressed gas is then injected into underground caverns. When energy is needed, the compressed air is released, the stored heat is added, and the warmed gas is run through turbines to generate electricity. Additional features improve the system’s efficiency.

Hydrostore has built a 1 MW pilot project in Ontario, Canada and is now commissioning a 2MW system as well. It is funded to build a 5 MW system in Australia next year and it is bidding for 300 MW and 500 MW systems in North America. The company has received equity funding from Baker Hughes, a large oil-and-gas services and equipment company.

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Storing energy in compressed air could finally become cheap enough for the big time

Photo courtesy of Hydrostor.

Earth Wise is a production of WAMC Northeast Public Radio.