The great advantage of fossil fuels is that they provide a constant supply of energy. The supply from renewable sources, however, fluctuates strongly. To complete the energy transition, we need to balance overproduction and shortages. Fortunately, the Netherlands is perfectly capable to achieve that. Will there be hydrogen flowing through our gas pipes in the future? TNO is working on various energy conversion and energy storage technologies to realise the energy transition at an acceptable cost.

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The need for underground energy storage


The need for underground energy storage

Large-scale underground energy storage is an important condition for a future-proof energy system and the success of the energy transition. We foresee that between 2030 and 2050 there will be a large demand for the storage of hydrogen in, for example, salt caverns, gas fields and aquifers (aquifer in the subsurface). In the white paper “Underground energy storage necessary for a future energy system”, TNO and EBN conclude that underground energy storage is an indispensable part of the infrastructure and that its development is necessary. Rapid action and direction are required to guarantee the security of supply and flexibility of our future energy system.

Sustainable energy

The rapidly growing amount of renewable energy generated from wind and sun is increasing the need for flexibility to keep supply and demand in balance. Where the supply of fossil energy is more or less constant, that of sun and wind varies greatly. By converting and storing this renewable energy on a large scale in times of surplus production, its consumption can be shifted to moments in time when there is a shortage.

The Netherlands is excellently positioned to realise large-scale storage with innovative conversion and storage technologies and infrastructure. This is particularly necessary in order to make efficient use of the rapidly growing amount of electricity that will soon be generated offshore and to prevent shortages occurring when the wind is not blowing and the sun is not shining.

Large-scale underground storage

Large-scale storage of energy underground, in salt caverns and empty gas fields, plays an important role in absorbing fluctuations in supply and demand on a scale of days or even months. The electricity from renewable sources is converted into hydrogen, for example, and transported to be safely stored underground for a longer period of time.

TNO has extensive expertise in the field of conversion and storage technologies to convert electricity into another form of energy or energy carrier and back again if necessary. This provides great flexibility between production renewable electricity and its use of by industry and households.

Relieving the electricity grid

TNO is working on various energy conversion and storage technologies to realise the energy transition at an acceptable cost. It concerns conversion of electricity or biomass to hydrogen or green gas (Power2Gas), from electricity to heat (Power2Heat), and to fuels and raw materials (Power2Fuels & Feedstock).

Conversion and storage provides flexibility and thus security of supply. This will make the future energy system reliable and affordable for consumers and businesses. The stored energy helps to cope with peaks in energy demand and supply, thus relieving the burden on the electricity grid and preventing expensive upgrades.

Flexibility through North Sea system integration

Various energy conversion and storage technologies essential to realise the energy transition

Large-scale storage is provided in salt caverns and in empty gas fields. The latter offers opportunities to reuse the existing platforms and pipelines: system integration. This is where everything comes together: conversion of electricity from wind into hydrogen, use of existing gas pipelines, storage in empty fields. This not only requires knowledge of electricity, gas and hydrogen per se, but also of all the connections between them, energy markets, networks, environmental aspects and economic feasibility.

In the
North Sea Energy research programme, TNO is working on integrating the energy functions from the perspective of technology, society, market and ecology and, together with partners, is putting the North Sea on the map as an exemplary region for the European energy transition.

Storage and immediate use

Conversion and storage enable energy generated from renewable sources to be shifted in time from moments of surplus due to abundant sun and wind to moments of high demand. Incidentally, conversion does not always mean storage.

The electricity converted to hydrogen can be used by industry directly in their processes or transported for heating in the built environment. Electrons are then converted into molecules, for which both transport and storage are much cheaper. In this way, electricity generated from sun and wind can be used in any form of energy at any time.

Wide range of technologies

Underground storage has played an essential role in securing our energy supply for decades. At Norg, Grijpskerk and Alkmaar, enormous quantities of natural gas are stored underground for times when production cannot keep up with our energy needs. These underground areas may be suitable for storing large quantities of hydrogen in the future.

Energy can also be stored in the form of electricity, although batteries are inadequate to do so on a large scale. Thousands of the world's largest batteries would be needed to store the amount of electricity generated in a single day by wind farms with a total installed capacity of 35 gigawatts.

To bridge such periods from one day to several weeks without sun or wind, a much more efficient solution is to convert the electricity to gas molecules for use for high temperature heat in industry, heavy transport and raw materials. TNO is working on a wide range of conversion and storage technologies for a robust, affordable and reliable energy transition.


LSES: Energy storage in salt caverns and gas fields

The project "Large Scale Energy Storage in salt caverns and depleted fields" (LSES) investigates large-scale storage of energy in the form of hydrogen (in salt caverns and empty gas fields) and compressed air (in salt caverns). TNO does this in collaboration with EBN, Gasunie, GasTerra, NAM and Nouryon, among others.

North Sea Energy

The North Sea is an ideal environment to contribute significantly to a climate-neutral energy system. There are opportunities for large-scale wind energy, hydrogen and underground CO2 storage.

The North Sea Energy research programme looks at linking these energy functions from the perspective of technology, society, market and ecology. TNO, together with its partners, is putting the North Sea on the map as an exemplary region for the European energy transition.


TNO coordinates the European research project Heatstore to develop technologies for the storage of thermal energy and to demonstrate these in field trials. This involves different configurations in which heat sources, storage techniques and utilisation of heat are combined.

IJvergas project

In the project 'IJvergas' TNO and partners researched the feasibility of a multifunctional energy island in the North Sea

Want to know more about our energy conversion and energy storage technologies?

Get in touch with Joris Koornneef.


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