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Industry Musings Blog

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ZG Providing Advanced Rail Energy Storage (ARES) Economic and Engineering Analysis Services

ZG is providing technical engineering services for an exciting new storage technology called ARES, which is a rail-based, gravity-powered energy storage technology that is more environmentally-responsible, durable, and cost-effective than other utility-scale storage alternatives. ARES technology uses no fossil fuel or water, produces zero emissions or hazardous waste, and has a 40+ year service life, with no degradation or thermal runaway.

ARES GravityLine’s TM fixed motor, chain-drive system draws electricity from renewables and/or the grid to drive mass cars uphill against the force of gravity – efficiently converting electrical energy into the potential mechanical energy of mass raised to a higher elevation. When the grid requires power, this process is reversed and the mass cars proceed downhill with the electric motors operating as generators, thereby converting the potential mechanical energy back into electricity.

The GravityLine TM storage system is made up of multiple 5 MW tracks and can vary in size from 5 MW to 1 GW of power and an equivalent range of energy (MWh to GWh) depending upon weight and number of mass cars, slope, and distance. ARES’ GravityLine TM design boasts duration flexibility of between 15 mins and 10 hours.

ZG’s engagement in the ARES project is critical to determining the economic value of the storage technology and its potential in the CAISO ancillary service market, which provides fast-responding resources that can be increased or decreased quickly to help maintain grid reliability. During periods when energy generation exceeds demand, the CAISO commands providers, such as ARES, to consume a specific amount of energy by charging in 15-minute increments. When the signal comes, ARES will begin charging, which provides ‘regulation down’ resources. That is when ARES mass cars will draw electricity from the grid, which powers their drive motors to move the mass cars uphill against the force of gravity — efficiently converting electrical energy into gravitational potential energy.

When the CAISO requires energy, or ‘regulation up’, this process is reversed, and the mass cars proceed slowly downhill with their motors operating as generators, converting the potential energy of the mass cars’ elevation back into electricity in a highly efficient 15-minute round-trip process.

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