Rail Energy Storage Project Conquering Western America

What is more than 4 miles (6.5 kilometers) long, full of rock and has a potential power output of 50 megawatts?

If you can't answer that question, don't worry -- not many have heard of a rail-based energy storage system -- a concept that will soon be launched on the southwestern border of the U.S. state of Nevada. Its designers have high ambitions for their project and are confident that this storage system can become an invaluable help in stabilizing the regional power grid.

Compared to traditional chemical batteries, the idea of storing energy using railway tracks is simple. During periods of low electricity demand, electrical power is transferred from the nearby power grid to electric motors that drag a bunch of heavy trolleys up a mountain or hill. There they will be, without loss of power (unlike chemical batteries), until the power grid does not need more electricity. After that, the trolleys will be released for free descent, down the slope. Their movement will send electrons back to the power grid through a regenerative braking system that uses the rotational energy of the wheels to generate electricity.

Cargonet with cargo

“They go up and down like toys,” says Francesca Cava, chief operating officer at Advanced Rail Energy Storage North America, the company behind the projects in Nevada. “By and large, the technology we’ve been using is over a hundred years old — we don’t have to wait for scientific breakthroughs to be profitable.” "

The whole point of the project is the way energy is stored and then released – a vital aspect of any power system with high penetration of variable solar and wind energy.

The only forces exploited by rail storage that are conceptually similar to pumped-storage power plants are gravity and friction. But, unlike pumped storage systems, the trolleys and rails on which they travel do not require convenient location of water resources, making them much more attractive to arid regions such as western Nevada.



Advanced Rail Energy Storage North America believes that the cost of operating their system will be half of what is required by a similar project of pumped storage power plants of the same capacity, and, importantly, will have much smaller environmental consequences.

The pilot project, which is an 800-foot (243 meters) railway, is just a quarter of the planned scale. Advanced Rail Energy Storage North America has begun planning its first commercial project, which the company plans to build near the California-Nevada border in partnership with Valley Electric Association Inc. (VEA).

The Valley Electric Association, a Nevada-based company, decided to work with a much larger operator, the California Independent System Operator.

The system also plans to create a reserve in the form of cargo on the top of the mountain, which trolleys could deliver during periods of ultra-high electricity generation.

“We are very excited to be able to roll out the new technology in southern Nevada,” said Tom Hasted, CEO of the Valley Electric Association. “Because of our location in the country’s solar belt, this technology will fit perfectly into our grid and has tremendous potential to develop and support the renewable energy sources we operate in the region.”

The region needs energy storage systems to support ambitious renewable energy targets, and is exploring options including new combined cycle plants to meet expected fluctuations in energy supply. California law requires solar, wind and other renewables to account for 33 percent of total electricity generation by 2020.



In a past life, the trolleys that will be used in this large-scale project, worked in the field of Australian mining. They were specifically designed to be extremely reliable and long-lasting, explains Kava. On a typical energy trip, each of the trolleys will carry about 230 tons of cargo in the form of rock and cement, descending and rising at a smooth angle of 6 to 9 degrees. After climbing to a height of 3,000 feet (914 meters), they will be securely attached to the docking station, where they will wait for the right moment.

During periods of low demand, trolleys will be able to unload at the top of the slope and return to the starting point empty to take a new load - thus it will be possible to increase generating capacity.

Each car will be equipped with a generator of 2 megawatts. This piece of equipment functions simultaneously as a motor and a generator, depending on the direction of travel, says Kava.



The average power deployment speed is five to ten seconds. That lags far behind chemical batteries, which can deliver full power instantly, but far outperforms combined natural gas power plants, which build up only about 8 percent of their capacity per minute.

Conventional coal-fired power plants, for example, can build up full capacity in a matter of hours, making them ill-suited to balancing the fickle generation from renewables.


Pilot project in California foothills shows how gravity can help conserve excess electricity

“Our capabilities exceed those of conventional batteries, but they do not reach the level of conventional power generation,” says Kava. “While the company is still in the process of building its first project, we have significant interest in this technology from other parts of our country, and even from some international companies,” Kava added.

Source: aenergy.ru