Underground Sun Conversion - Start

Geological history in fast motion: renewable natural gas produced from solar power and water, 1,000 metres underground

03/02/2017 | Press release

  • Unique worldwide: the Underground Sun Conversion project
    The highly encouraging results of the Underground Sun Storage research project (2013-2017) are the basis for the unique Underground Sun Conversion project, which is now under way.
  • Geological history in fast motion: natural production of “renewable natural gas”
    Over 1,000 metres below ground, where natural gas formed millions of years ago, “organic natural gas” can now be produced from hydrogen and carbon dioxide for the first time – using a microbiological, environmentally friendly process initiated specifically for this purpose by RAG and its project partners. 
  • Storing renewables
    Renewable energy can be stored in underground gas reservoirs – renewable natural gas is an energy source for industry, heat generation and transport that can enhance security of supply.
  • Outstanding potential
    The aim of the research project is to carry out research into the principles for producing large quantities of renewable natural gas in the future, and storing it in environmentally friendly, naturally formed reservoirs. This will provide urgently needed flexibility for renewable energy sources. 

Vienna and Pilsbach, 2 March 2017: The successful Underground Sun Storage project, which focused on the storage of wind and solar energy in naturally formed gas reservoirs, is to be taken to the next stage. Building on the research conducted so far, for the first time the Underground Sun Conversion project will enable production of natural gas directly within a gas reservoir using a microbiological process initiated specifically for this purpose by RAG, and to store it in the same reservoir. 

This innovative method is unique worldwide, and recreates the natural process by which gas originates, but shortens it by millions of years – geological history in fast motion.

First, hydrogen is produced from solar or wind energy and water in an above-ground facility, and then injected into an existing gas (pore) reservoir, together with carbon dioxide – creating a sustainable carbon cycle. At a depth of over 1,000 metres, in a relatively short time naturally occurring microorganisms convert these substances into renewable natural gas which can be stored in the same reservoir, withdrawn as needed at any time, and transported to consumers via the existing pipeline network.

This environmentally friendly process has three major advantages:

  • Carbon neutral thanks to carbon cycle
    Renewable natural gas is carbon-neutral, if carbon dioxide that originates, for example, from burning biomass – is utilised for the production process. This creates a carbon cycle.
  • Renewable energy becomes storable
    Solar and wind power output fluctuates due to changing weather conditions, meaning that production cannot be adjusted to demand. The problem of storing renewable energy is solved by converting it into renewable natural gas.
  • Existing infrastructure is used
    Infrastructure already in place can be used for the natural production process, as well as for underground storage in natural gas reservoirs, and environmentally friendly transportation to consumers.

The aim of the RAG-initiated project, implemented in collaboration with partners, is to carry out research into the principles for producing large quantities of renewable natural gas using a carbon-neutral process, and storing it in environmentally friendly, naturally formed reservoirs, which will in turn provide urgently needed flexibility for renewable energy. 

The project has been designated a flagship project by the Austrian Climate and Energy Fund and granted EUR 4.9 million as part of the fund’s energy research programme. The Austrian consortium is managed by RAG. The total cost of the project amount to EUR 8 million.

The project partners are the University of Leoben; the BOKU - University of Natural Resources and Life Sciences, Vienna (Department of Agrobiotechnology, IFA-Tulln); acib - Austrian Centre of Industrial Biotechnology; the Energy Institute at Johannes Kepler University Linz; and Axiom Angewandte Prozesstechnik.

The project is scheduled to be completed by the end of 2020. 

Detailed information

In-depth research on methods to sustainably reduce carbon dioxide emissions is being carried out worldwide. As the shift to erratic renewable generation gathers pace, the need for storable forms of energy is greater than ever. There is a particularly strong need for energy sources with high energy density, such as methane, for industrial processes, heat generation and transportation.

Research performed as part of the newly launched Underground Sun Conversion project is aimed at identifying a process that offers a way to produce high-density energy forms as well as finding a solution to the question of storage. Another objective is to make full use of the gas infrastructure already in place in many parts of the world. The starting point is power-to-gas technology, which converts excess power generated from renewable sources (wind or solar) into hydrogen and/or methane by means of electrolysis. 

The aim of the research project is to use existing gas (pore) reservoirs as natural reactors. The methanisation process and storage take place in underground pore reservoirs, representing a huge source of potential, and providing the urgently needed flexibility that renewable energy currently lacks.

The process replicates and repeats the biogenic process by which gas originates. Methanisation takes place naturally in underground geological formations, but the process is shortened by millions of years. 

Initial laboratory tests conducted as part of the forerunner project Underground Sun Storage – which is also supported by the Austrian Climate and Energy Fund – show that hydrogen injected into the reservoir with carbon dioxide is converted into methane by microbiological processes. This enables the creation of a sustainable carbon cycle. Laboratory tests, simulations and a scientific field test at an existing RAG reservoir will be carried out in collaboration with a group of project partners. A further objective is to test whether the outcomes can also be achieved at many other reservoirs all over the world. Consequently, the results that the project aims to achieve are highly significant to further enhancing Austria’s leading position in seasonal storage of renewable energy in natural gas reservoirs, and for the widespread export of both the technology and know-how underlying the process. 

“Austria is again breaking new ground for renewable energy. This research project is a world first: we are producing natural gas from solar and wind power for the first time – and within a few weeks instead of millions of years. We are doing the work of an entire geological period at rapid speed. And we are taking another step towards energy independence for Austria,” said Jörg Leichtfried, Federal Minister of Transport, Innovation and Technology.

Theresia Vogel, Managing Director of the Austrian Climate and Energy Fund, said: “Our Energy Research Programme supports selected application-driven projects that go far beyond conventional research funding. This is the only way that we can realise positive effects for the climate and achieve the necessary technological breakthroughs and cost reductions. Underground Sun Conversion will deliver insights that point the way forward to the energy system of the future.”

RAG CEO Markus Mitteregger explained: “Our research project is unique worldwide. It is like geological history in fast motion – and has massive potential. It is carbon-neutral, solves the huge problem of storing renewable energy, and allows us to use infrastructure that is already in place. It is also extremely environmentally friendly, because it reproduces natural microbiological processes on a reduced scale, and we can store the renewable natural gas produced at the same site – in a natural gas reservoir over a thousand metres underground. The results from lab tests conducted so far in the Underground Sun Storage project are very promising. We are even more excited about the additional insights that the Underground Sun Conversion project will generate.”

Further information on the project can be found at www.underground-sun-conversion.at 

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Background information

Solar and wind power output is erratic because of changing weather conditions, meaning that generation cannot be adjusted in response to demand as is the case with conventional power stations. In some parts of Europe, such as the north of Austria’s Burgenland province, on windy days the amount of power generated by wind farms is already well in excess of demand. With the growth in wind and solar generating capacity, and because of the intermittent nature of wind and sunshine, energy storage is becoming an increasingly pressing issue. Even Austria’s pumped storage plants in the Alps are no longer sufficient to meet this need. 


RAG Rohöl-Aufsuchungs Aktiengesellschaft
Elisabeth Kolm
T +43 (0) 50724 5448

Austrian Climate and Energy Fund
Katja Hoyer
T +43 (0)664 8861 3766