Storage is one of the main challenges in global energy. Power consumption is uneven throughout the day, which makes power plants often operate in a suboptimal mode. Industrial-scale energy storage facilities can help make the electricity grid more flexible by smoothing out peaks in consumption. The market potential for energy storage is constantly growing and is forecast to be more than RUB 100 bln ($1.32 bln) by 2025, according to Rusnano. Andrey Bryzgalov, General Director of Energozapas, spoke about the energy storage system their team has developed, what difficulties the project faced, and when the project is going to be implemented on an industrial scale.
Who invented solid-mass gravity storage plants?
Established in 2016, Energozapas is now the only company in Russia working on gravitational energy storage that is not PSH (pumped storage hydroelectricity). The idea of storing energy using solid weights was born in 2012. Chairman of the Supervisory Board of the Market Council nonprofit partnership Yury Udaltsov met with Andrey Bryzgalov who then headed Uniscan, a company that made electronic devices. Udaltsov suggested storing energy by lifting and lowering a heavy mass. The innovative automated technology is based on raising a heavy solid weight vertically and lowering it to store and release energy. The company employs about 80 specialists and 40 subcontractors. Energozapas has been a resident of the Skolkovo Technopark since 2016.
Problem: how to store surplus energy?
The need for long-duration energy storage is high around the world, as such systems would solve some pressing problems for the power industry. First and foremost, they would equalize the load on power generation units reducing the accident rate. Second, they would reduce grid maintenance costs. Power peaks inevitably occur in industrial production, causing overloads of power supply substations. Storage devices installed at the substation or at the consumer end would smooth out consumption peaks and reduce the load on the power grid. Third, energy storage is also in demand on the off-grid market.
The vast majority of energy storage systems in the world are pumped storage hydropower (PSH) plants. According to the US Department of Energy, they account for more than 98% of the world’s total capacity. A pumped hydroelectric energy storage has two reservoirs located at different levels and interconnected by a system of pumps and generators. During periods of low demand, water is pumped from a lower elevation reservoir up to a higher elevation, consuming low-cost off-peak power from the grid. During peak consumption, water is released through turbines to generate expensive electric power and return it to the grid.
The largest pumped storage hydropower plant in Russia, Zagorskaya, is on the Kunya River in the Sergiyev Posad District of the Moscow Region. Its capacity is 1.2 GW, and gross output, 7.2 GWh. However, the use of pumped storage hydroelectricity has its limitations. Building this facility requires a large area and a difference in height elevation. This is a significant disadvantage given Russia’s predominantly flat terrain. Also, a natural high-capacity source of water is needed. In case of an accident at a pumped storage power plant, there is a risk of a man-made disaster. Considering these factors, the Energozapas team proposed its own solution to use the potential energy of a solid mass instead.
Solution: earth versus water
After Andrey Bryzgalov met Yury Udaltsov, the team spent five years developing the concept of an energy storage using weights. In 2017, they presented the first prototype of a gravity storage power plant.
Lifted Weight Storage (LWS) operates in pretty much the same way as the PHS, only it uses compressed soil instead of water. The facility consumes energy from the grid lifting the weights up to the height of a few hundred meters and generates energy as needed when the weights go down affected by gravity. Capital expenditure of an LWS becomes economically efficient with the capacity above 300 MWh. The efficiency of the prototype is 60%, and will grow to 80% with an increase in capacity.
LWS plants can be built on any terrain and do not require any high relief. The area they use is immeasurably smaller than what is needed to build a PHS. According to Bryzgalov, an LWS with the same capacity and output parameters as the Zagorskaya PHS plant will take only 2.5% of its area. It is also important that the operation of the LWS is environmentally safe, and in case of an accident, there is no danger of a technogenic disaster.
It should be noted that other countries are also working on projects that involve raising a solid mass to generate gravitational potential energy. For example, the German company Heindl Energy has a project where a one-piece 250 m wide granite piston is lifted up by a water column in a cylinder.
In a project by ARES (United States), heavy weights are driven uphill by mass cars and then, also connected to the cars, are deployed downhill while delivering electric power.
Still, each of these examples also requires a unique landscape or a huge body of water. That was why Energozapas started looking for a completely new approach, which it realized in 2018 in the Novosibirsk Academic Town.
Lifts carrying energy
The solution proposed by Energozapas is a system of lifts. A 20 m high LWS prototype with a capacity of 10 KW was built in 2018. Eight shafts, or vertical columns connected by horizontal and slanted cross beams, are located along the walls of the building. Lifts carry weights up the shafts while consuming excessive energy from the grid. The weights are secured at the top while lifts go down for a new load. The weights are pulled down affected by gravity, which activates a motor generating electric energy.
LWS lifts have no counterweights. Durable polymer sacks filled with compressed soil are used as weights. The weights are reinforced with geomesh, to reduce lateral pressure and lower demands for the case material.
The structure is surrounded by a “skirt” to eliminate the impact of the wind. The skirt has a width of one-quarter of the LWS radius and converts the horizontal pressure of the wind into vertical load. The developers also considered cushioning seismic vibrations. This is where the structure of the LWS helps. A specific number of weights are moved at any given time while the remaining weights serve as plummets and kill the vibration.
The next step towards a full-fledged industrial-scale LWS is construction of a pilot plant on the territory of the Skolkovo Technopark. The pilot will be 80 m high and have a capacity of 2.4 MW.
Why we need the pilot
The pilot LWS is planned for launch in 2021. The project raised RUB 1–2 bln ($13–26 bln) in funding from the National Technological Initiative that implements projects of the Russian Agency for Strategic Initiatives. The cylindrical structure has a diameter of 30 m and is reinforced with so-called Shukhov mesh to withstand the wind. Inside the cylinder, there are recuperative lifts and weights as well as the battery’s supporting frame.
Andrey Bryzgalov says the structure in Skolkovo will serve as a showroom for testing the electrophysical installation and demonstrate results to potential investors. He noted that building a 300 m tower would have been impractical because energy producers who may potentially offer funding must first see a functioning structure and successful experience of its construction and operation. The pilot structure will consist of the same mechanical and electronic components and will be based on the same construction technology that will be reproduced in the industrial-scale LWS. Energozapas engineers also presented a VR model of the pilot LWS that shows the interior and exterior with a great degree of detail.
If all the technical specifications are approved, Energozapas plans to launch the first industrial-scale LWS in 2025. Standing at 300 m tall and covering an area of about 1 sq km, the plant will have a storage capacity of 10 GWh and operating capacity of 1 GW, both parameters adjustable to customer needs.
Energy storage using LWS may work for any type of energy systems. In renewable energy, it will supply electricity during weather conditions that are not suitable for renewable energy production. In thermal power plants, exhausted plant units may be replaced with gravity batteries instead of new but identical plant units. The other units will operate in a mode that reduces depreciation to a minimum while ensuring maximum efficiency. Nuclear power plants must operate at a steady capacity to avoid accidents. Batteries can help accumulate their excessive energy.
Bryzgalov notes that the Energozapas project is also targeting foreign markets. The energy storage facility could be in demand in such countries as India, China, Vietnam and Japan. Belarus, where the Ostrovetskaya Nuclear Power Plant is located, is also interested in an LWS, as is the Northwestern District of Russia that has reported an excess of energy.
Energozapas currently cooperates with Russian energy companies and its project is part of the National Technological Initiative.
By Kristina Firsova