A startup with a basic energy storage technology has just hit a significant project milestone. And the technology in no way involves batteries or novel electrochemistries.

ARES (Advanced Rail Energy Storage) was just granted a right-of-way lease by the Bureau of Land Management (BLM) for its proposed 50-megawatt/12.5-megawatt-hour commercial-scale, gravity-based rail energy storage project.

The project will serve as a merchant ancillary-service provider connected to the Valley Electric Association (VEA) and responsive to commands from the regional transmission operator, the California Independent System Operator (CAISO). VEA is in the CAISO balancing area.

ARES uses electricity from the grid to drive loaded locomotives up a grade. As the train cars descend, their motors then act as generators and provide electricity to the grid. According to VP of operations Francesca Cava, the round-trip efficiency of the system is 85 percent.

The small train cars are more conventionally used in mining operations and are designed for durability, according to Cava. They move up and down an 8-degree slope with an elevation change of about 3,000 feet. According to an application with the Nevada PUC, "The rail facilities do not meet the definition of a railroad and the Federal Railroad Administration has not exerted jurisdiction over the rail line and related equipment." The project sits on 106 acres of public land in Southern Nevada, near Pahrump in Clark and Nye Counties.

The first-of-a-kind project is expected to cost $55 million. Cava told GTM that "millions" had already been invested in the company, and the firm has "commitments for about 60 percent" of its financing and hopes "to round out the remainder of the funds in the next few months." Although the company has demonstrated its technology on a small-scale Tehachapi, Calif. wind farm, this is not yet a technology that can be financed by conventional means.

Source: KGET TV 17

But the big news for ARES is that tortoises, birds, wild horses and burros, cultural sites, water issues, etc. have been dealt with, and “after a robust Environmental Assessment and Biological Opinion concluded a Finding of No Significant Impact, BLM wrote a Decision and granted the project,” according to Greg Helseth, BLM's Southern Nevada renewable energy coordination office program manager.

ARES claims its "fast response technology bridges the power gap between smaller battery and flywheel installations and far larger pumped storage hydro -- at a lower life-cycle cost than batteries, a higher energy-to-power ratio than flywheels, and a greater efficiency and far faster ramp-rate than pumped storage."

ARES looks to bid into the daily CAISO ancillary services market (regulation energy management) to provide grid support such as frequency regulation. To connect the ARES project to the grid, VEA will need a new substation, a new transmission interconnection line and an upgrade of the existing 230-kilovolt transmission line.

ARES looks to begin construction in late 2017 or early 2018, with operations beginning in early 2019, according to the application with the PUC (PDF).

The company is still going to have to raise the balance of its financing to get the project built, however.

Non-battery energy storage: CAES, pumped hydro, thermal and gravity power

As Jeff St. John has reported, the world’s two first compressed-air energy storage (CAES) projects -- the 290-megawatt plant in Huntorf, Germany, built in 1978, and the 110-megawatt McIntosh, Alabama plant, built in 1991 -- have been able to provide very cheap long-duration energy over decades of operation, by boosting the output of natural-gas-fired power plants at the sites. But much like the pumped hydro storage projects they compete with in terms of scale, they’re expensive and large, requiring hundreds of millions of dollars and years of lead time to develop. They also need to be coupled with natural-gas power plants in order to return their stored energy to the grid effectively.

A few startups have tried to develop CAES technologies with and without huge underground caverns. SustainX pursued above-ground tanks to hold compressed air that could later be delivered to a turbine. SustainX raised about $30 million from investors including Polaris, General Catalyst, RockPort Capital, Cadent Energy Partners, and GE Energy Financial Services. General Compression touted near-isothermal CAES in underground caverns to enable "dispatchable wind." That startup raised more than $35 million from investors including Northwater Capital Management, U.S. Renewables Group, Duke Energy and Serious Change. These two startups attempted to merge in 2015, but both have since wound down their operations.

Another startup targeting containerized CAES, LightSail Energy, recently went through a second round of layoffs after raising more than $70 million from French energy giant Total, Peter Thiel, Bill Gates, Khosla Ventures, and Innovacorp. The firm is now focusing on cheap carbon fiber tanks in the near term.

Source: LightSail Energy

There is more than 120,000 megawatts of pumped storage hydropower capacity worldwide. A new pumped-hydro installation can take more than a decade and cost billions before a single watt of power is banked. It also has daunting siting limitations -- it requires two large reservoirs at different elevations and a willing utility commission and environmental community -- and lots of water resources. There are about 38 pumped-storage projects operating in the U.S., providing more than 20 gigawatts, or nearly 2 percent, of the capacity of the electrical supply system (EIA, 2007).

Gravity Power, a venture-backed energy storage startup, proposes a vertical column excavated hundreds of feet into the earth filled with a column of water. An immense weight rests on the water, which is raised, like a piston, to store energy and lowered to discharge energy using an additional return pipe (here's the patent application). The pressure depends on the vertical dimension of the "heavy-concrete" weight moved up and down, while the distance traveled dictates the storage time available. Round-trip efficiency is about the same as conventional pumped hydro energy storage according to the company -- in the range of 75 percent to 80 percent.

Ice Bear offers a solution for peak-load management by freezing ice at night when power demand is low and electricity is cheap, and then using that ice to provide cooling to power-intensive air conditioning units during the heat of day. Each Ice Bear can defer about 10 kilowatts of power use per day, and reduce carbon dioxide emissions by up to four tons per year, as reported by Julia Pyper.

Isentropic's pumped-heat electricity storage (PHES) system is based on the first Ericsson cycle and uses a heat pump to store electricity in thermal form. The storage system uses two large containers of gravel, one hot and one cold. Electrical power is input into the machine, which compresses/expands argon gas, which in turn is passed through the two piles of gravel, where it gives up its heat or coldness to the gravel. In order to regenerate the electricity, the cycle is reversed. The temperature difference is used to run the system as a heat engine. Isentropic claims a round-trip efficiency of 75 percent.