Regenerative braking is the winner in the energy storage world, the competition is over, lithium-ion has been destroyed - is a statement you're not going to hear anytime soon. Nonetheless, it is a new energy storage alternative that could assist utilities when they need more energy to continually power the grid. Regenerative braking is a method of taking kinetic energy from moving parts and then storing that energy and reusing it. Electric vehicles have been using the method and trains have as well. As a train applies its brakes, a battery captures the kinetic energy.

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Credit: ARES

Now, a company named ARES (Advanced Rail Energy Storage) is taking this technology more seriously and championing a new project in California. The company says their grid-scale energy management system is capable of providing utility balance when it is needed.

The way it works is through the use of 300-tonne train-like vehicles on a train track that will be self-driving. When a power utility is in need of power, the vehicles - who would have made their way uphill when the utility had an excess of power - will travel downhill. Their motors then become energy generators and generate electricity in the act of travelling downhill and then braking. The cabs have rocks in them so that they are weighted down and faster when coming downhill. 

The engineers say the system life on these vehicles is 40 years or more and can produce 12.5 megawatt-hours of energy. ARES confirms that by 2019 they will be operating over 106 acres of land in Pahrump, Nevada. The project would end up costing $50 million +. However, whether this becomes the most sustainable way to ensure everyone in the world can look forward to cheaper, cleaner energy remains to be seen. For now, funding is even going in to regenerative braking to see if we can solve the energy trilemma. 

ARES Chief Executive, Jean Kelly, said: "ARES Nevada will be a world-class facility and a point of pride for Nevada. The power production is clean and renewable - operating of the project requires no water or fossil fuel and creates no hazardous waste or emissions."