Sustainability
Technology

25.08.2015

Renewable energy? Let’s store it!

More and more wind parks and solar plants are popping up on the landscape. They may not always look elegant, but they are essential if we are to cut greenhouse gases by at least 80% by 2050 as called for in the EU Roadmap. An ambitious goal and one which requires a solution to a particular problem: What should we do with the surplus power generated by the wind and the sun? After all, at the moment it is difficult to store it.

At the end of 2014 there were already 268,000 wind turbines in action all over the world. They contribute around three percent of global energy supply. Until recently Europe was the world leader in producing wind power, but it has been edged out by Asia in the past year.

So far, so good. However, a lot of surplus energy is also generated in the wind parks – for example when there are strong winds or when the demand for energy is lower. The problem is that it is currently difficult to store this energy. It has even gone so far that the turbines have to be switched off despite ideal conditions, in order to avoid overloading the electricity grid. At the same time there are days when the rotor blades don’t turn – because there simply isn’t the necessary wind. Therefore we need a technology which can balance out these fluctuations – compare the graph below –, so that we can use green energy flexibly. The solution could be hydrogen combined with the existing natural gas network.

Energy consumption

Predicted fluctuation in the production of renewable energy and consumption on eleven ‘fictional’ days in a row. Source: EVN Group – Forecast 2020 for Lower Austria (in Kw)

How to get the wind in the pipeline

One of the visionaries behind the brand new Power-to-Gas technology – the transformation of power from renewable energy sources into hydrogen or methane – is Michael Sterner, Professor for Energy Storage at theUniversity of Applied Sciences in Regensburg: “The gas network is the infrastructure with the largest storage capacity in the whole of Europe. This is the ideal complement to an energy supply dominated by mains power.” But how to get the wind into the gas pipeline? “For this, the power produced from wind energy has to be converted into hydrogen”, explains Helga Prazak-Reisinger, Innovation Manager at OMV, which has been exploring the “Wind2Hydrogen” storage concept since 2014.

"Transforming electricity into hydrogen is the missing piece of the puzzle which we need to expand renewable energy in the future. This technology allows us to store surplus production or to produce renewable hydrogen for future use on the road."

Helga Prazak-Reisinger

Innovation Manager at OMV

Hydrogen – the energy store

Hydrogen is the most common element in the universe and is found in every living organism in its compound form. Moreover, it can store three times as much energy as petrol. But what can we do with “H2”? “On the one hand, hydrogen can be used in hydrogen vehicles with a fuel cell – green power on the road. This does not generate any pollutants, the only emission is water”, explains Helga Prazak-Reisinger. “On the other hand, hydrogen is an ideal interim storage system. It is relatively simple to store it in the existing gas network, which serves both as storage and a means of transport.” The gas can then be converted back into electricity whenever needed or used as heating supply, for heating a gas boiler for example. This means that no energy is lost – every gust of wind is used.

High pressure to turn wind power into hydrogen

The direct path from wind power to hydrogen is via electrolysis, a process which uses electricity to split water (H2O) into hydrogen (H2) and oxygen (O). This is exactly what the newly opened wind2hydrogen pilot plantin the OMV gas station in Auersthal in Lower Austria does – and more. Namely, hydrogen has a considerably high volume, which makes transport and storage difficult. The high-pressure electrolyser in Auersthal allows the hydrogen to be compressed right from the moment it is produced at 163 bar pressure, instead of using a maintenance intensive compressor – unique within Power-to-Gas. Just to compare: a car tyre has about three bar pressure.

The pilot plant also allows research into how the electrolyser works in flexible conditions, for example when there is no wind over a longer period. “Here we are simulating the power profile of a wind park, testing future business cases and gathering data on the daily operations of plants of this kind. Furthermore, we are getting important information on how and in which natural gas networks hydrogen can be stored”, explains Helga Prazak-Reisinger. “I see massive potential here. With this technology you can start small; you can flexibly adjust the systems – for example by installing an electrolyser directly at a filling station and producing hydrogen on site – and then expand it in modules. What I find so fascinating about Wind2Hydorgen is that it doesn’t generate any emissions and or any waste whatsoever – we gain pure, green energy.”

Find out more about the wind2hydrogen research project, which we are realising with Fronius, EVN, HyCentA, the Energy Institute of the Johannes Kepler University Linz and is supported by the Climate and Energy Fund, in our film:

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