RES Rentier: Gravitational energy storage will allow us to stabilize the National Power System for 50 years

OZE Rentier SA is a company aiming to transform the renewable energy industry by employing gravity-based electricity storage facilities.

Tomasz Zieliński, the President of the Management Board at OZE Rentier SA, and Andrzej Tersa, the Vice-President of the Management Board at OZE Rentier SA, provided insights into the advancement of this technology and its role in the energy transition.

How do gravitational energy storage (GME) work?

AT: During times when there’s an excess of energy generated by wind and solar farms, we store this energy by raising a heavy block to a height of approximately one hundred meters using a reversible engine. When there’s a shortage of energy in the power system or within our power plant, we lower the weight, causing the engine to act as a generator and thereby releasing the generated energy back into the grid.

Can gravity energy storage be compared in some way to pumped-storage power plants?

AT: They share a similar underlying principle. In pumped-storage power plants, water serves as the energy storage medium and is pumped from the lower reservoir to the upper one. When energy is required, the water flows back down to the lower reservoir through turbines, generating energy. In Gravity Mass Energy (GME), the energy is stored in a heavy block lifted upward as the storage medium.

What are the weaker points of gravitational energy storage?

TZ: The primary limitation of Gravity Mass Energy (GME) lies in the height of the structure, which can have a visual impact on the landscape, much like wind turbines.

What advantages do these solutions have over the currently best-known lithium-ion batteries?

TZ: Operational lifespan: Up to 50 years with adequate maintenance, and a consistent system efficiency is maintained throughout the entire life of the gravity energy storage facility.

Environmental safety during the construction and use of the facility (no risk of fires or leaks) eliminates the necessity to extract rare earth metals.

Furthermore, after the facility’s operational phase, approximately 99.9% of the construction materials used in GME can be recycled, ensuring minimal environmental impact.

Why are these solutions still so unpopular?

TZ: The primary driving factor is the cost of energy and the relatively high initial construction expenses associated with Gravity Mass Energy (GME), even though they are notably lower than those of pumped-storage hydroelectric power plants. Considering current electricity prices, GME stands out due to its consistent efficiency, hovering around 75%, and an operational lifespan of 50 years, making it economically competitive. This is despite construction costs that are comparable to lithium-ion storage facilities.

Another crucial catalyst for the development of GME is the European Union’s decarbonization requirements and the growing necessity for continuous energy storage to stabilize the system, especially with the rapid increase in renewable energy sources within the National Power System, alongside the lag in the development of new energy storage technologies.

It’s worth noting that the decreasing costs of energy from renewable sources during peak operating periods compel the exploration of relatively inexpensive and efficient energy storage technologies, rendering GMEs financially attractive.

Do they have the potential to play an important role in the energy transition?

The energy transformation has already begun, and the development of renewable energy installations and electricity storage is part of it

AT: If the European Union maintains its commitment to energy development focused on decarbonization and climate neutrality, a gradual shift away from fossil fuel-based generating units will be necessary. For both environmental and economic reasons, retiring aging and inflexible coal units with lower power capacities is already a priority, without the construction of replacements. Instead, there should be a shift towards establishing additional distributed solar and wind power plants with local energy storage facilities and other energy storage systems to fulfill the requirements for grid stability.

The transformation of energy should also prioritize producing and storing energy where it’s needed. Instead of constructing large-scale generating units and massive pumped-storage power plants with extensive transmission infrastructure, a more practical approach would be to create a network of renewable energy facilities, including wind, solar, and biogas, with energy storage located in the same regions where energy consumption is high, such as near major cities or industries with substantial energy demands. As coal units are phased out, plans could be devised to build new renewable energy generating units in areas of high energy consumption. Simultaneously, the power grid in these regions could be modernized, enabling the further expansion of solar and wind power plants, supported by energy storage facilities. This approach would facilitate the growth of renewable energy sources by extending local transmission lines and incorporating new renewable energy and Gravity Mass Energy (GME) installations. It would be a more cost-effective, rapid, and environmentally friendly solution.

The energy transformation is already underway, and the development of renewable energy installations and electricity storage is a crucial part of it, including GMEs, which are considered more eco-friendly compared to pumped-storage power plants and lithium-ion battery storage facilities.

Do we already have such warehouses in Poland? (fully, commercially implemented)

TZ: While Gravity Mass Energy (GME) technology is not yet widespread, there is a noticeable development trend. The first GME facility, boasting a 5 MW capacity, was constructed in Switzerland. In Shanghai, China, there’s a GME facility with a 25 MW capacity and 100 MWh capacity. Additionally, a 36 MWh storage facility is currently under construction in Texas.

At OZE Rentier SA, we are in the process of seeking permits to construct a prototype of a gravity energy storage facility at our solar power plant, which features photovoltaic (PV) panels on single-axis trackers to optimize power plant efficiency. This facility will consist of a tower reaching a height of 135 meters.

What are your forecasts for the gravity energy storage market in the coming years?

Humanity is forced to look for new solutions. We can locate GME virtually anywhere, at wind and solar generating units, at nodal points of the system

TZ: Poland’s topography primarily consists of lowlands, covering 91% of the country’s area. This limits the potential locations for constructing pumped storage power plants. Furthermore, the distribution and transmission grid infrastructure impose constraints on the placement of new solar and wind installations. The cost of building and expanding the transmission network necessitates the exploration of alternative solutions to align with EU environmental requirements and grid stability. While nuclear energy is highly efficient, its development takes time and poses safety concerns.

If we intend to transition away from hydrocarbons in the coming century, renewable energy is not only the future but a necessity. However, the widespread use of lithium-ion and cadmium batteries, along with rare earth metal mining, raises environmental challenges. Global reserves of rare earth metals are limited, posing difficulties in supporting renewable energy stabilization.

Geothermal energy holds promise for the future but faces current limitations related to technology, drilling depths, and associated costs, likely requiring decades to develop. Hydrogen solutions show potential but are still on the horizon.

Given these challenges, Gravity Mass Energy (GME) presents an appealing option. GME facilities can be located virtually anywhere, from wind and solar generation units to key points in the grid. A GME facility with a capacity of over 20 MWh can be built on just one hectare. This technology offers a 50-year solution for stabilizing the National Power System. Moreover, altering legislation to treat GME facilities like pumped-storage power plants, streamlining the permit process, can significantly boost their development.

AT: In the coming years, Europe and Poland, as they progress in the decarbonization journey, require systemic solutions and the most cost-effective electricity to maintain economic competitiveness. Legislative changes treating GMEs as smaller, systemic pumped storage units could greatly facilitate the green transformation. Additionally, integrating GME into transmission lines that already transport green energy represents a consistent step toward a zero-emission economy and a more ecologically sustainable approach to life on our shared planet.

There are at least two primary applications for Gravity Mass Energy (GME):

• A system that can be employed by Distribution System Operators (DSO) and Power System Entities (PSE) to stabilize the National Power System.
• A solution for large renewable energy producers, enabling them to sell surplus energy generated through hourly contracts during peak demand hours.