Dirt Batteries to Help Bridge Gap in Wind, Solar

A startup company called Energy Vault is developing a system that uses gravity to store renewable energy generated by wind and solar panels.

The system works by hoisting hundreds of large 24-ton bricks made of compressed dirt up the side of a building. It hoists the gigantic brick batteries using energy previously generated by solar panels or wind turbines, then stores them inside the structure. (Source: cnet.com)

When power is needed, the bricks are lowered, spinning electrical power generators in the process. The bricks are abundant and cheap to make, and replace the need to purchase expensive batteries (such as lithium-ion) that require mining of special metals.

Gravity Batteries to Compliment Coal, Hydro Power

The push towards green energy has led to significant growth in the use of solar and wind power. However, one of the biggest challenges with this type of energy is the issue of availability.

Solar panels and wind turbines produce electricity only when the sun shines and the wind blows. This results in a mismatch between power production and usage, which makes it difficult for utilities to adjust to rapid changes in demand.

For example, when power demand in a city is at its highest (typically in the evening), there is often a shortage of renewable energy. This has led to the use of fossil fuel-powered plants to bridge the gap, resulting in increased carbon emissions. To overcome this challenge, researchers are exploring various energy storage solutions that can help ensure that electricity is available when it is needed.

Systems Being Tested in China and Texas

Energy Vault has tested its technology at a smaller scale in Switzerland, where the company is headquartered. The company is now building two large-scale facilities, one in China and the other in Texas, to test the viability of gravity storage technology.

The Chinese system is located in a 400-foot-tall building and will have an energy storage capacity of 100 megawatt-hours - enough to power 3,400 homes for an entire day. The Texas system, on the other hand, is located in a 460-foot-tall (but narrower) building and will provide power company Enel with 36MWh of capacity.

Advantages to Gravity Batteries

Unlike traditional batteries, gravity batteries can be placed in a wide range of locations.

For example, they can be used in urban environments or in remote locations, and their design can be customized to fit the specific needs of a location. In areas with a lot of wind, gravity batteries can be designed to take advantage of the wind to lift the bricks, reducing the need for solar panels.

The potential uses for gravity batteries are almost limitless. They could be used to provide power to homes and businesses, as well as to provide backup power in case of an outage. They could also be used to store excess power generated by renewable energy sources, such as solar and wind, which could then be used to supplement the grid during times of high demand.

Additionally, gravity batteries could be used to power electric vehicles, reducing our reliance on fossil fuels.

Cost to Implement

Cost will be a major factor in determining which storage technology prevails, including initial manufacturing and continuing operations.

A 2022 US Department of Energy study concluded that gravity energy storage is relatively expensive in smaller installations. Where it's most economical is in high-capacity systems that generate power for relatively long periods of time - 10 hours or more.

Energy Vault has not disclosed the cost of the two systems under construction, but the company agrees that the technology offers advantages for long-duration power needs. (Source: energy.gov)

Longevity is also a cost factor over the lifetime of the plant. Batteries lose capacity with use, the same way phones don't run as long after a couple of years of ownership. However, gravity storage components, like pulleys and generators, can be maintained indefinitely.