A Battery That's 100x Cheaper

Company Information



Energy Storage


Wilmington, DE

Airthium makes large-scale batteries that can store renewable energy over long durations.

This company’s battery can store up to 100x more energy than traditional batteries, and has the potential to provide renewable energy more affordably than fossil fuels all year long.

Within the next 30 years, solar and wind will supply almost half of the demand for electricity worldwide. Wind and solar energy are already the cheapest forms of electricity in many parts of the world.

The problem is that they only produce energy when it's sunny or windy. To compensate for short periods of bad weather, lithium-ion batteries are used — like the ones in electric cars, but much bigger.

These batteries work most of the time to provide a steady supply of electricity. But sometimes, inclement weather can last for days, even weeks. At that point, lithium-ion batteries run dry quickly, leaving users in the dark.

In order to satisfy demand for electricity 365 days a year, these batteries would need to be 100x larger. But then they’d be 100x more expensive.

Airthium has created a solution. Its large-scale battery is designed specifically to store energy over long periods of time. In doing so, this company is targeting the battery energy storage market, projected to reach nearly $20 billion by 2027.

Airthium’s battery is a hybrid system that has two functions: it can store electricity over very long durations (months to years), and store electricity on shorter durations (10 to 40 hours).

The centerpiece of the system is a proprietary Stirling engine, which acts like a reversible heat pump. It can both convert heat into electricity and electricity into heat, all with very high efficiency.

To perform short duration storage, the engine converts abundant solar or wind energy into heat. Then, the heat is stored in large molten salt tanks. (Molten salt is a kind of “industrial lava” that is 100% recyclable.) When electricity is needed, heat is taken from the tanks and converted into electricity by the engine running in reverse.

To perform long duration storage, a clean chemical plant called an “Electric Haber-Bosch plant” converts electricity, water, and air into the chemical Ammonia. Ammonia is then stored, again, in large tanks in liquid form, at a mild temperature. Ammonia can be stored this way for years without any noticeable degradation.

When electric power is needed, ammonia is taken from the tank, burned in a clean way (i.e., without harmful emissions), and the heat of ammonia combustion is used to operate its Stirling engine in generator mode.

Airthium is the only company developing a high-efficiency ammonia-fired Stirling engine. All existing competitors use either two- or four-stroke engines, or gas turbines. Both of these options are internal combustion engines, meaning ammonia is burned inside the heat engine.

The problem with this approach is that there is little room to adjust the conditions under which ammonia is burned (e.g., pressure and temperature levels). Ammonia doesn’t burn easily, and can create very large amounts of nitrogen oxides. If this happens, the engine will need to use a large, expensive reduction system known as a Selective Catalytic Reduction (SCR) to eliminate these oxides from the exhaust.

Since Airthium uses a Stirling engine, it can tailor the burner to the best possible combustion conditions. The bottom line: Airthium can save substantially on SCR costs and have the best chance at the cheapest, highest-performing engine on the market.

To start, Airthium will sell its energy storage systems through renewable energy project developers, and target solar and wind farm owners. Once enough systems have operated in the field, the company believes it will be able to secure financing to start a leasing business.

Airthium got its start at the Ecole Polytechnique in France, one of the most prestigious higher education institutions in the country.

In 2017, the company completed the Y Combinator accelerator program, and then raised a pre-seed round of funding.

More recently, Airthium won multiple awards, including the Prix Gerondeau award by the Zodiac Aerospace (this awards program was created in 2011 to promote the emergence of innovative projections), and Prix de Innovateurs, another award rewarding innovation.

Airthium is now building a single-kilowatt prototype of its battery at the Air Liquide Research Center in Paris. It has successfully tested a prototype of the compression head of its engine, a crucial part of its system. This is what converts electricity into heat and vice versa, and is the most expensive part of the battery.

The company is seeking capital to continue developing this prototype and begin working on a 100-killowatt prototype that will be used for demonstration purposes to potential clients.

Team Background

Andrei Klochko - Co-Founder & CEO

Prior to starting Arithium, Andrei worked as a post-doctoral fellow at the Laboratoire de Physique des Plasmas at the Ecole Polytechnique, one of the most prestigious higher education institutions in France. He studied plasma-assisted combustion and air flow control in aerospace applications.

Before that, he was a Ph.D. student studying uniform gas heating in plasmas, which has applications in combustion and ignition enhancement, as well as aerodynamic flow control.

He earned a Master’s degree in Engineering and Physics from Ecole Polytechnique.

Franck Lahaye - Co-Founder & COO

Before starting Airthium, Franck was Director of Meteor Trading, a space-related company focused on satellites. While there, he designed solutions for media-related customers.

Prior to that, he spent five years at Intelsat, one of the largest commercial satellite operators in the world. He initially served as a sales representative, then moved to a sales director position.

Earlier, Franck was a sales and project coordinator with Enomatic Southeast, an Atlanta-based technology company that sells high-end systems for serving and dispensing wine.

He earned a Master’s degree in Entrepreneurship from ICN Business School.