Why thermal batteries are key to making better use of clean energy

Wind and solar are now the cheapest sources of electricity on the planet. But despite plenty of international reports and mainstream news coverage highlighting this important transformation, even those most closely following climate and energy issues often lose sight of what this trend truly means.

As a starting point, imagine a simplified grid operating entirely on fossil fuels. Now that renewables are cheap, they can be deployed quickly by enterprising developers; these early wind and solar projects yield strong returns, as they’re able to sell power at a lower cost than incumbent power producers whenever the wind is blowing, or sun is shining.

As more and more renewables go online, however, renewables projects must compete to sell their power – causing market energy prices to plummet when renewable generation is high, and demand is low.

By its very nature, clean energy generation in any one place is synchronized; when one wind turbine in an area spins, so does nearly every other turbine in that area. So, when wind or solar deployment reaches the point where it’s able to meet our electricity needs during periods of peak generation, the laws of supply and demand drive the value of any additional generation during that hour towards zero.

When high generation coincides with periods of low demand, this trend is even more pronounced – often forcing renewable generators to temporarily cease production. As a result, once-lucrative projects are now left with an increasing share of electricity generation that is, in the eyes of the grid, close to worthless.

While these projects still produce plenty of high-value power, this effect remains significant enough to impact project economics and slow deployment in places with lots of existing renewables.

This dynamic is already starting to play out across the globe. But far from portending the end of the clean energy era, this surplus renewable generation provides an opening to start powering entire sectors of our economy with low-cost, clean electricity.

Using flexible technologies like thermal batteries, we can unlock a new, cost-effective energy source without compromising on reliability. Such systems can transform excess electricity into heat and then, like typical batteries, store the energy to be discharged 24/7.

To understand how dirt-cheap renewables can transform our energy future, let’s take a look at the unassuming capital of the US clean energy economy: the Great Plains. From the Texas Panhandle to the grasslands of North Dakota, this American “Wind Belt” saw some of the first large-scale wind deployments in the world and now boasts the highest renewable energy penetrations in the country. South Dakota, for instance, already produces more than half of its energy from wind power.

As a result, the giant wind farms that dot this region have increasingly been forced to curtail their generation when production is high and demand is low – resulting in up to a fifth of potential power generation being completely wasted, at the expense of their bottom line. Meanwhile, faraway urban areas with massive electricity loads are prevented from accessing this clean electricity due to transmission bottlenecks.

Across the Wind Belt, wholesale electricity prices are cheaper than Henry Hub natural gas – the benchmark for cheap gas prices in the US – for 30%, 40%, or even 50% of the year. Every year, these percentages increase as more renewables are deployed.

This is not an isolated trend. As we deploy wind and solar faster than anyone predicted, we will increasingly see the same pattern play out in every corner of the globe.

Across the Wind Belt, thousands of factories have so far been unable to tap into the low-cost energy that’s being wasted right in their backyard, instead burning natural gas and coal onsite while electricity is practically being given away for free.

Despite being located among some of the cheapest power sources on Earth, these factories are unable to access this low-cost electricity for a simple reason: they run 24/7, and the clean inexpensive power is intermittent. The same will hold true for millions of industrial facilities around the world, which collectively account for 37% of global energy use.

Here lies one of the biggest opportunities in the energy sector today: bridging the gap between always-on industrial demand and inexpensive intermittent power.

There are many conceivable paths to converting intermittent electricity into always-on heat and power, from lithium-ion batteries to green hydrogen, but none are as cost-effective and scalable as thermal batteries – the solution that companies like Antora, a member of the World Economic Forum's Clean Power, Grids and Electrification programme, are already beginning to deploy across the Wind Belt.

By heating up low-cost, domestically produced and abundant materials like solid carbon in an insulated module, we can now store energy at the scale, efficiency and cost needed to electrify even the most extreme industrial processes.

To fully unleash the potential of thermal batteries, we must ensure that market rules and rate structures enable them to access surplus and low-value power at rates that reflect the true cost of generating and delivering it.

In doing so, we can unleash the deployment of more renewables on the grid and make better use of our existing grid infrastructure, lowering the cost of a clean grid for everyone.