If we captured a mere fraction of the solar and wind energy available on earth, we could make far more electric power than we’d know what to do with. The resulting power would involve zero emissions, no fuel to continuously buy, and no risk of contamination from radioactive waste.
The perennial argument against these two free and permanent power sources is that we can’t always count on them being available to provide electricity. But one emerging technology, liquid-air energy storage, could change that in the near future. The system uses the power inherent in temperature differentials to create electrical power. If adopted on a big scale, it could mean a huge breakthrough toward making solar- and wind-generated energy more practical and widespread.
The Problem with Solar and Wind Energy
Electricity made by photovoltaic cells when struck by the sun and electricity produced by wind-driven electric turbines suffer from the same drawback: They are what power grid managers refer to as intermittent power generation. When the sun isn’t shining brightly enough or wind speeds don’t exceed a certain threshold, the devices intended to capture their energy don’t produce electricity.
For electric power utilities, this presents a big problem – the electric power grid requires the supply and demand of electricity to be in balance at all times. When they’re not, the system suffers equipment failures that eventually lead to blackouts. Renewable energy sources are limited in how big of a role they can play in the power grid because their power output can’t be manipulated at will — at least not in the way fossil and nuclear power plants can.
How Liquid Air Energy Storage Works
If you take ordinary air and chill it enough (down to -385 degrees Fahrenheit, or -196 degrees Celsuis), it will actually go from being a gas to a liquid. The power from solar or wind energy can be used to chill the air down to the required temperature (said air might also be purified and might have all gases except nitrogen removed).When brought back up to normal temperature and its gaseous state, the formerly liquid air rapidly expands. Much as with traditional steam power, the energy released as the air expands can be used to rotate a turbine, which in turn spins an electrical generator. That electricity can then be fed into the power grid.
The supercooled air stays in liquid form at regular, atmospheric pressure – no need for complicated and dangerous high-pressure tanks. It can be stored in containers and expanded to create electricity when needed – whether it happens to be in the dead of night or in the breezeless haze of summer.
Comparison to Battery Storage
How does this stack up to say, storing electricity in traditional batteries? Officials at United Kingdom-based firm Highview Power Storage, one of pioneering companies in liquid air energy, concede that it’s not as electrically efficient as batteries. A good deal of the original energy content sneaks away as assorted losses before it can be converted into electricity, making the system about 50-percent efficient. Even so, the capital costs of building a liquid air setup is cheaper than buying batteries, and batteries have to be replaced every few years. A liquid air plant is supposedly good for at least a couple decades, with worn out parts easily replaced using common tools.
In addition, the plants can make use of “waste” heat from nearby industrial facilities to boost their efficiency.
Highview has set up a small demonstration plant to show the technology in action, and says it could build a deployment-ready system capable of 100 megawatts or 1,000 megawatt-hours.
We might be waiting several years before we see this particular flavor of technology complementing wind farms and solar arrays on a meaningful scale. But it’s encouraging to know that one more alternative is on the horizon to help us break the grip of environmentally harmful energy production.