The Biden administration is pushing its Energy Earthshots Initiative that aims to accelerate innovation and bring life-changing products to market. That involves “long-term energy storage,” which could radically alter the way electricity is produced and consumed by permanently tipping the scales toward green energy.
If voracious energy users such as data centers are to hit their net-zero targets, they must run their enterprises on renewable energy. But the sun does not always shine and the wind does not always blow. So long-term energy storage is vital. Their dilemma: most storage assets can kick in for a few hours but they can’t discharge for weeks at a time. What now?
“Without inexpensive long-duration energy storage, we would never be able to have genuine zero-carbon power. You must have enough storage to last for extensive periods,” says Shankar Ramamurthy, chief executive of the Energy Internet Corporation (EIC,) which just said it is working with Intel Corp.
“It is most important to have 24-7 operations that are fully powered with renewable energy that use long-duration storage,” he continues, in a phone interview. “We have a good sense of the costs of our systems and the engineering. The design expertise is highly specialized.” Data centers, he adds, are the focus because they are major economic contributors and huge consumers of electricity.
The goal is to provide “long-term viable storage that won’t cost more” than the short-term lithium-ION batteries that are prominent today. Those batteries can be charged and discharged multiple times but eventually, they wear down. According to Ramamurthy, it will take six months to design a technically feasible model and another six months to demonstrate it.
Specifically, EIC’s solution uses isothermal Compressed Air Energy Storage, which stores surplus renewable power as compressed air. Higher power scales — more than 40 megawatts — are then stored in depleted oil and gas reservoirs as well as salt caverns and aquifers while amounts less than 40 megawatts can be harnessed above ground. Compressed or liquid air is used to generate power when needed. Reliability, it adds, is 99.99%.
The Holy Grail
EIC says that this technology is superior to the most prevalent form of long-term storage: pumped hydro, which generates power by running turbines with water flowing through them. “By using compressed air to provide the pressure head, we avoid large bodies of water at different elevations. By using off-the-shelf components, like water pumps and turbines, and well-understood thermodynamics, we avoid new hardware components or processes,” says Ramamurthy. While new hydro dams cost billions to construct, compressed air energy storage is more practical.
But can it work? In April, a company out of Toronto, Canada called Hydrostor also said it would develop 1,000 megawatts of long-term energy storage in California — part of the state’s effort to develop 1,600 megawatts of such storage by 2026. It too will use compressed air energy storage, which can perform for 12 hours at a time.
To be clear, storage devices come in many forms: the prevailing ones today are batteries that link to the transmission grid where they siphon off power at night and store it. It is then dispatched during the day when prices rise. There are also fast-response flywheels that are useful for short-term needs.
There’s thermal energy too, which captures heat and cold to create energy on demand or to offset energy needs. And there’s mechanical storage, which harnesses kinetic energy. In simple terms, the faster an object moves, the greater its kinetic or gravitational energy. Think river flows and the generation of hydropower.
While batteries are meeting many of today’s short-term storage needs, they cannot provide long-term storage: lithium-ion batteries can keep the electrons flowing for four-to-eight hours, although “flow batteries” can release energy for 15 hours. If a catastrophic event such as a wildfire occurs, then diesel generators are used for long-term relief — but limited by the amount of available fuel.
Meantime, there’s hydrogen. Solar panels will generate excess electricity which, through an electrolyzer, is turned into pure hydrogen. That gas is stored in a tank before being piped through a fuel cell. It is a form of long-term energy storage, although the cost of producing “green hydrogen” from clean sources needs to drop before it would become commonplace.
“Energy storage is the holy grail that we need to conquer. Everyone is trying to look into this,” says Mohan Kumar, an Intel Fellow, in a phone conversation.
“If you produce energy and it is intermittent, it is not useful,” he adds. “Whatever the storage solution, it has to solve that problem. In the data center world, we are focused on how to get to a carbon-neutral footprint. At Intel, we watch all the technologies. The next step is to do a ‘proof of concept’ (for compressed air energy storage that demonstrates viability.) Once that is done, we will have some results to share.”
Given that the White House has a goal of using 100% clean energy by 2035 and of being carbon-neutral by mid-century, the imperative for developing affordable and reliable long-duration storage has never been greater. Public investment in the tools could make those goals realistic — the same way it helped deflate the cost of solar panels. As for long-term storage, the Biden administration wants to see a 90% price drop as the economies of scale are built. If that happens, not only can the country conquer its climate change challenges but it can also curtail capital-intensive expenses in power plants and transmission lines.