Frequently Asked


We have put together some commonly asked questions to give you more information about Green Hydrogen Hub.

If you still cannot find an answer to your question, please contact us.


Where will the Green Hydrogen Hub be located?

Dutch headquartered Corre Energy will be the lead developer of the hydrogen-fuelled CAES facility and coordinate development across the entire project, leading key commercial and funding activities. With over 30 years of collective renewables and storage development experience, it is developing a pipeline of hydrogen-based storage projects with electrolysis in Europe.

What is the expected CO2 reduction?

Our targets are approx. 600,000 tonnes per year reduction of CO2 emissions. Due to Denmark’s interconnections with neighbouring countries, part of the reduction will be seen outside Denmark’s borders, which we see as an advantage for achieving the European climate goals.

What is PtX?

Essentially, Power-to-X seeks to convert the green electricity produced by wind turbines and/or solar cells (Power) to something else, symbolised by the “X”. For instance, how we can use our green electricity from wind turbines in transport, e.g. cars, shipping and aviation. With the GHH we will have the possibility of storing the electricity generated from the wind turbine, and therefore be able to charge a car with green electricity even if there is no wind.

The process of converting from renewable electricity to “X” includes three elements: 1) biogas/methane, 2) CO2 and 3) hydrogen. The hydrogen is essential as this is required to use the CO2. The water is split into Hydrogen (H) and Oxygen (O2). The oxygen will then be applied in industrial processes and the hydrogen will be used for renewable energy and fuels.  

Electrolysis also creates heat – on a long-term basis it could contribute to the district heating system and essentially to domestic heating.

How is hydrogen relevant in the green transition? And is it a good idea to use hydrogen in such a project?

Hydrogen is the first step in all PtX value chains. Production of hydrogen via electrolysis can, together with hydrogen storage, utilise excess energy from wind and solar. Hydrogen can be used in many sectors where direct electrification is difficult. Storing gas or hydrogen underground is a known technology and it is very safe. Thus, hydrogen becomes an essential part of our contribution to the green transition.

The combination of hydrogen storage and CAES makes it possible to live 100% CO2 free, and have electricity from renewable sources every hour all year round. It is our assessment that hydrogen-powered CAES is competitive if it is properly integrated with solar and wind.

What are the figures behind the project?

Our targets for the three elements of the value-chain are a 350MW electrolysis plant, 250 GWh hydrogen capacity and a 320MW CAES.  

GHH fits very well with other energy storage technologies. What’s special with the GHH is that large amounts of energy can be stored for a very large time period, for example from summer to winter.

How will this Green Hydrogen Hub contribute to the security of supply of electricity in Denmark?

As Greenhouse Gas (GHG) reductions impact security of supply, Green Hydrogen Hub Denmark actually increases Danish security of supply by providing new inertia based flexible sources of electricity generation along the whole supply chain by fully integrating growing variable renewable sources.

What is hydrogen?

Hydrogen is a chemical element with symbol H and atomic number 1. It is the simplest, most abundant and lightest element in the universe. Hydrogen constitutes about 75% of the universe’s mass.

Hydrogen gas is rarely found alone in nature because it is usually bonded with other elements. Hydrogen can be found in water (H2O). In summary, hydrogen combines with many other elements to form different types of compounds such as water (H2O), ammonia (NH3), hydrogen peroxide (H2O2).

Hydrogen is the key priority in the European Green Deal and in supporting Denmark’s ambitious clean energy transition. Renewables will decarbonise a large share of Denmark’s electrical consumption, but not all of it. Clean green hydrogen will plug this gap.

Is hydrogen safe to store & handle?

Hydrogen, such as petrol, diesel and natural gas, contains large amounts of energy and must therefore be treated responsibly. When handled and stored properly, hydrogen is just as safe as all other commonly used fuels, but more importantly, it is less toxic and it is an indispensable component in achieving our climate goals.

How can we produce hydrogen?

The vast majority of Hydrogen currently produced worldwide uses steam reformation of natural gas and water electrolysis. Water electrolysis is simply a means to split up water into its two gas constituents that is hydrogen and oxygen. Using an electrolyser fully powered by renewable energy, hydrogen can be split from oxygen by sending an electrical current between two electrodes. When the current flows through the electrodes, hydrogen and oxygen are split.

Hydrogen is seen as a green or pure fuel because H2 is an environmentally friendly fuel with no associated CO2 emission. As such hydrogen has the potential to dramatically reduce our dependence on imported oil as well as reduce the dangers associated with Greenhouse Gas emissions. 

How does the Green Hydrogen Hub integrate primary renewable energy sources?

The GHH take excess renewable energy that is normally wasted and converts it to hydrogen, as well as storing the renewable energy in the compressed air energy storage cavern. Converting and storing excess renewable energy provides consumers with the lowest cost of decarbonisation, this accommodates sector coupling via case which is an inertia-based zero emission generator that balances fluctuating renewables.