Sustainable energy storage enabling a fossil-free future

A real solution of the climate problem with modern and large-scale energy storage.

Pumped Hydro Storage was started by enthusiasts with a background from renewables, and with a strong desire to make a difference in the energy transition.

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The World’s Most Sustainable Balancing Power Enabling a Fossil-Free Generation

Long experience

Pumped Hydro’s and SENS team has an extensive experience of renewable energy development and planning

Focus on the future

We are a growing company with co-workers that are all passionate about the same thing – to enable the energy transition and a sustainable future

Our unique and sustainable solution

Pumped Hydro Storage’s solution enables large-scale electricity storage with the help of the proven technology of pumped storage. This is combined with the unique idea of constructing it in abandoned mines. The storage method (PSH) is characterized by low cost, high efficiency, and a long service life.

SENS, through PHS, is a part of NewSETS - Novel storage solutions for a sustainable transition

With the sole focus on energy storage, NewSets project combines demonstrations, feasibility studies and analyses with communication and dissemination to better enable the execution of projects and to highlight the climate change mitigation efforts.

The project includes the demonstration of underground pumped hydro storage and feasibility studies of seasonal heat storage, alongside comprehensive studies of the effects of the storage solutions on the energy system. Behind NewSets is a consortium lead by Flexens, and is supported through the ERA-Net SES MiCall19 framework.



of all stored electricity is Pumped Hydro




years life-cycle

Lowest cost of storage

Low environmental impact

A sustainable idea for a greener future

The energy transition creates a need for large-scale energy storage, when fossil energy production is replaced by renewable and weather-dependent energy production. We offer the most efficient and mature technology for storing energy. This storage method is characterized by a low-cost, high round-efficiency, large scale, and a long life-cycle of 60 years.

When wind and solar power makes up a larger share of the energy system, the need to store energy increases – to secure the balance between production and consumption.

Pumped Hydro’s innovative solution means a more efficient and flexible pumped storage technology, which is installed in disused mines. This way, the mines are transformed into a positive asset in the green transition. At the same time, costs can be kept down by using existing infrastructure such as access points to the power grid and roads.

Pumped Hydro’s technical design is unique as it enables almost immediate response. This means that the company can effectively operate in the on different ancillary services markets, which are markets that are used to ensure the balance in our power grid.

This way, Pumped Hydro can create several parallel revenue streams by contributing with energy storage, arbitrage trading and frequency control. The company’s customers include energy companies, large energy consuming companies and industries that want to ensure a 100% power generation and mine owners. They also include closed power systems, and islands in need of a stable energy supply.


Increasing need for storage

With an increasing share of renewable power in the energy production, it is becoming increasingly important to find innovative solutions for energy storage. Solar and wind power are so called intermittent energy sources. This means that their production cannot be planned but instead relies on the current weather conditions. The greater the share of production that these sources account for, the more difficult it becomes to match the electricity production and consumption.

The electricity grid also has its own limitations. These mean that you cannot transport electricity large distances without it costing energy in the form of losses in the grid. To reduce these losses, local energy storage is needed.

In order for the growth rate of sustainable electricity to be able to increase, more investment is needed in storage solutions that can secure the electricity supply at all times. The long-term climate work therefore requires new, innovative technologies for large-scale energy storage.

Various energy storage technologies

With a growing share of weather-dependent electricity production, also the price volatility in the electricity market is increasing. At the same time as there is a growing need for frequency regulation in the electricity grid, i.e. the ability to continuously secure the stability between supply and demand.

Competitive energy storage must be cheap, have a high efficiency and be able to respond quickly to changes in the electricity grid. It must also have a long life-cycle, low environmental impact, and a long discharge time. The only existing technology that meets these requirements is pumped storage in mines, which SENS and Pumped Hydro is the only one to offer.

The energy storage market

Underground pumped hydro power meets all the requirements placed on the single most important type of energy storage that enables energy transition. In terms of competing technologies, PSH is the dominant way of storing energy, with 94 percent of total capacity globally (International Hydropower Association, 2018). By 2040, the global energy storage market is expected to grow to 1,095GW / 2,850GWh [ BloombergNEF]. Investments over the next 20 years are expected to amount to $662 billion, which would correspond to over 50,000 large-scale underground pumped storage plants of 100 MW each.


Our solution

Pumped Hydro Storage’s solution is based on an understanding of the power markets and future revenue streams for pumped storage hydropower plants. We have implemented this understanding in software to simulate revenue streams from electricity trading and balancing services for the power grid. We use the knowledge to design and optimize hydro storage facilities. These are easily adapted to local markets and operating conditions.

Each facility uses a unique and customized management schedule. This maximizes the utilization of the energy storage for the benefit of its owners. The technology itself is proven and consists of pumps, generators, and turbines in a synchronized system. With the help of this, water in a closed system is moved through corrosion-resistant pipes between an upper and a lower reservoir.Because the reservoirs are built in underground mines, the cost of these are low and the environmental impact is minimized.

Our technology

Pumped storage hydropower (PSH) is a proven technology for energy storage. Today, more than 94% of the world’s total installed storage capacity is in the form of PSH. However, it is very difficult today to build new pumped hydropower. The reason for this is that the construction of new dams can lead to a major impact on local ecosystems and watercourses.

Conventional PSH collects water in a lake or reservoir at a higher altitude. From there, the water is led down through power a turbine that generates electricity and released into a lower reservoir. Pumped Hydro Storage have developed a technology to enable reservoirs to be constructed underground.

Disused mines are often considered an environmental burden and a scar on the landscape from industrialization. Through our innovative solution, they can instead become assets for large-scale energy storage. The mines also have the advantage that they often already have access power- and road infrastructure. This is normally a large cost for energy projects and overturns the finance prospects.

At Pumped Hydro Storage, we create value from a residual product in the industry. Through this, our solution arouses interest in both the energy, mining, and sustainability worlds.

Hydropower plants often have an upper and a lower reservoir. The water is stored in an upper reservoir and sent via a turbine to the lower reservoir or water stream when electricity is needed. This can be when the sun is not shining, or the wind is not blowing. With a power system that is increasingly reliant on weather dependent electricity production, the need for this type of backup-power will be increasingly important. In a pumped storage hydropower plant, the water can also be pumped back to the upper reservoir when there is an excess of energy.

Funktion vidkraftverk turbin

How it works

Step 1:

Surplus energy in the power grid is used to pump the water and filling up the reservoir.

Step 2:

When there is a power insufficiency, the water is led back to the lower reservoir through a turbine to generate electricity back to the grid.

Said about Pumped Hydro Storage

International Energy Association

Between 2021 and 2025, more than half of new hydropower capacity additions in Europe will be pumped storage. Europe’s pumped storage growth is prompted by the need for system flexibility to integrate increasing shares of variable renewable electricity (IEA, Renewables 2020).

International Hydropower Association

As a result of a resurgence of interest in the technology, with more than 100 projects in the pipeline, IHA estimates that pumped hydropower storage capacity is expected to increase by almost 50 per cent – to about 240 GW by 2030. (IHA)

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