Hydrogen Ultra-LDES
UKEn are experts in hydrogen-ready Ultra long duration energy storage (Ultra-LDES), providing the secure, massive, long-term solution the country needs. Our role is to build the invisible infrastructure that acts as the National Energy Bank.
Ultra-LDES refers to energy storage systems capable of reliably discharging electricity for extended periods. These technologies are the key enablers needed to integrate massive amounts of variable renewable energy into the grid seamlessly.
UKEn is building the infrastructure that will underpin our national clean energy reserve.
As renewable generation grows, the UK needs to capture surplus energy when it is abundant and store it for the days, weeks and seasons when wind and solar cannot meet demand.
Batteries are highly effective at balancing the grid over hours, but they are not designed to store the vast amounts of energy required over longer periods.
Without Ultra-long duration energy storage (Ultra-LDES), these gaps must continue to be filled by fossil fuels – increasing costs, undermining energy security and making Net Zero harder to achieve.
Clean hydrogen stored in purpose-built salt caverns offers the best Ultra-LDES solution for closing this energy gap.
What is hydrogen?
Hydrogen H2 is the simplest and most abundant element in the universe.
On Earth, it almost always exists combined with other elements (like in water, H2O). When separated, it is a powerful, zero-emission energy carrier.
When hydrogen is burned or used in a fuel cell, its only by-product is water, making it a clean fuel substitute for natural gas or gasoline.
What are the benefits of hydrogen energy?
Hydrogen is an incredibly versatile and powerful zero-emission energy carrier. When it is used in a fuel cell or burned for power, the only by-product is pure water, which means using hydrogen eliminates harmful atmospheric pollutants and greenhouse gases.
Its high energy density (by mass) makes it an excellent clean fuel for sectors that are difficult to decarbonise, such as heavy transport, shipping, aviation, and high-heat industrial processes.
Furthermore, hydrogen can be produced from multiple sources including electrolysis powered by renewables (Green Hydrogen) or from natural gas with carbon capture (Blue Hydrogen), offering a flexible pathway to meet diverse energy needs across various industries.
The path to a resilient, Net-Zero grid is clear, and it requires a geological approach that is proven and safe and capable of meeting future energy requirements.
What is hydrogen energy storage?
Hydrogen energy storage is the process of converting surplus renewable electricity into hydrogen, storing that hydrogen, and then converting it back into power when needed.
It is a critical form of “Power-to-Gas-to-Power” storage that solves the seasonal energy challenge. The input of renewable electricity can come from wind or solar power, or from the electrolysis of water to make hydrogen gas. The output is dispatchable electricity.
Once produced, these large volumes of hydrogen must be stored safely and securely for months until the energy is needed. This requires massive, geological storage, which is where salt caverns come in. Hydrogen can be compressed to high pressures and then compressed and pumped into an empty salt cavern. It can then be held indefinitely.
How it works
Generate green fuel
When the wind is high and the sun is bright, massive electrolysers convert surplus renewable electricity into Green Hydrogen (the cleanest form of hydrogen) by splitting water.Storing energy at scale
The compressed hydrogen is injected deep underground into salt caverns. These vast, purpose-built chambers are the only technology that can store the Terawatt-hours (TWh) of energy needed for seasonal balancing.Powering the nation on demand
When electricity demand is high and renewables are low, the stored hydrogen is quickly withdrawn and converted back into dispatchable electricity using gas turbines or fuel cells.
The UK needs between 12 and 39 TWh of hydrogen storage by 2050 to secure a Net-Zero future, according to National Grid's FES reports.
This is a massive infrastructure challenge that requires immediate commitment. Investing in hydrogen energy storage will deliver the following goals:
- Unmatched energy security
Ending reliance on imported fossil fuels to plug the seasonal gap. - Grid stability
Providing the critical buffer that allows 100% intermittent renewable energy penetration. - Industrial decarbonisation
Providing the reliable fuel source (hydrogen) that heavy industry, shipping, and large transport need to cut carbon emissions.
FAQs
The UK's transition to a Net Zero energy system will cause a massive surge in electricity demand. According to NESO's FES report, total annual electricity demand is expected to rise from approximately 290 TWh today to a range of 705 to 797 TWh by 2050. Hydrogen contribution is forecast to range between 98 TWh and 325 TWh.
P2G2P describes the cycle of hydrogen energy storage. It involves converting surplus Power (renewable electricity) into Gas (hydrogen), storing it, and then converting it back into Power (electricity) when needed.
Existing batteries are effective for short-term storage. They cannot store the massive amounts of energy required for seasonal storage (holding power generated in summer for use in winter).
Green Hydrogen is produced using renewable electricity and electrolysis, resulting in zero emissions. Blue Hydrogen is produced from natural gas, with the resulting $CO_2$ captured and permanently stored.
Input: Surplus renewable electricity (from wind or solar).
Process: Water electrolysis creates hydrogen gas.
Output: Dispatchable electricity or a clean fuel source.
Yes. The technology leverages decades of experience in storing natural gas. Salt caverns are inherently secure because the surrounding salt layer is non-porous and naturally self-seals.
It provides a reliable fuel source for heavy industry, maritime shipping, aviation, brewing, and commercial road transport.
By acting as a critical buffer, it ensures the national grid can handle the volatility of intermittent renewable power, preventing system imbalance and potential blackouts.