In the past decade, renewable energies have advanced leaps and bounds and dramatically dropped in price. Wind and solar have become scalable, tradable as commodities, and have even outgrown their government subsidies as they become increasingly competitive with fossil fuels. Renewables are ready to take center stage in the urgent fight against climate change and have shown themselves to be capable of displacing fossil fuels. But there are still some major hurdles in the path towards a completely renewable world, and the biggest of those is energy storage.
Renewable energies like wind and solar power are variable — meaning that the amount of energy output fluctuates over time. As these forms of energy production are dependent on the weather and whether the sun is shining, it stands to reason that their flow of energy to the grid is marked by peaks and valleys. What’s more, renewable energy output is often at odds with energy demand. For example, as it gets dark and solar panels stop absorbing the sun’s rays, everyone starts turning on their lights, sucking energy from the grid at the same time that solar farms stop producing it.
In order for renewable energy to work, large-scale, dependable, and affordable energy storage is key. These energy storage centers are tasked with collecting excess energy when the sun is shining and the wind is blowing and then maintaining a regulated, steady flow of that energy to the grid. Of course, grids and batteries don’t only have to contend with a one-way flow of energy anymore. Unlike the standard energy landscape run by fossil fuels, the grid now receives two-way traffic as energy consumers also become producers in their own right thanks to residential solar panels. Updating the nation’s grid infrastructure and retrofitting it to fit the new millennium is also a major imperative for keeping up with the rapidly expanding clean energy transition.
There are many potential solutions for energy storage, some of which are relatively standard, like lithium-ion batteries, and some of which are a little more space-age, like green hydrogen. So far, batteries are far and away the predominant solution. In fact, CNBC has declared that we are currently living in “the battery decade” thanks to the massive demand from both the energy storage sector and the electric vehicles industry. But lithium-ion batteries have their drawbacks.
“The Renewable Revolution Has A Lithium Problem,” as Oilprice reported back in 2019. While renewables may be, well, renewable, lithium sure isn’t. It’s a finite resource which is only found in bulk in certain parts of the world, re-creating some of the same geopolitical issues that have plagued fossil fuel supply chains for years. China currently dominates as much as 90% of the supply for some of the rare earth minerals that are used in battery production, and the United States and China could easily be headed toward a renewable energy resource war as the energy storage sector heats up and proves to be increasingly lucrative.
For these reasons, among others, there has been a concerted and creative effort to come up with alternative ways to store energy. One of the newest potential solutions on the scene comes in an ironically low-tech package: concrete blocks. Energy Vault, the company currently working on storing energy in concrete, received over $100 million in Series C funding last month. Here’s how it works: when renewable energy facilities are creating excess power, a mechanical crane lifts concrete blocks 35 stories.
When demand catches up to and then outpaces production, the automated crane simply lowers those blocks, and with a little help from gravity the cables spin turbines which create more electricity. The heaviest of these blocks weighs 35 tons (70,000 pounds or 31,751 kg), and they are made of a kind of eco-concrete made of soil and locally-sourced waste. These apparatuses will have a storage capacity of up to 80 megawatt-hours, and be able to continuously discharge 4 to 8 megawatts for 8 to 16 hours, according to reporting from Singularity Hub.
Sometimes the simplest solutions are the most elegant. This could certainly be the case for the deceptively stone-age startup, which has already charmed plenty of investors. While Energy Vault is just getting the ball rolling, the startup will start to fulfill contracts around the world starting next year.