This article is part of our special report Renewable gas.

The excess wind and solar electricity generated at times of oversupply could be used more systematically to produce synthetic gas, providing a convenient way of storing renewable energy that would otherwise be lost. The potential is huge, and can be used to heat homes during winter, argues Beate Raabe.

Beate Raabe is Secretary General of Eurogas, the trade association representing the interests of the gas industry in Europe.

She spoke to EURACTIV’s energy and environment editor, Frédéric Simon, ahead of Eurogas’s Annual Conference: “Renewable gas: balancing our energy” taking place on 27 October at The Hotel in Brussels.

“Renewable gas”: that sounds a bit like an oxymoron. Is this not an attempt to make natural gas look greener than it really is?

Our objective is to inform people that gas is not just natural gas but can also be renewable. People are familiar with the term biogas for instance. But not all renewable gas is biogas. And that’s why we are saying “renewable gas” in order to cover the whole range of renewable gases that exist.

So what are the gases that can be considered renewable?

Let’s start with biogas. People know that biogas is made from manure and that many farmers produce it and use it directly on the farm or in cooperation with other farmers. Because it’s gas that has impurities so it cannot be injected directly into the grid. You can use it to produce power straight away, you can use it locally in combined heat and power (CHP) plants. So there is a lot of biogas that goes directly into CHP.

But you can also upgrade biogas and bring it up to a standard that makes it suitable to be injected into the gas grid – and then be blended with natural gas. That’s biomethane. That’s the beauty of it – you can use the existing gas grid in order to transport and store this renewable gas.

And there are lots of sources from which you can produce biogas – manure, sewage and waste, whether agricultural waste or municipal waste. We have millions of tonnes of waste in Europe and a lot of that would be suitable to be turned into biogas and biomethane. So it’s a great opportunity to contribute to the circular economy and solve the issue of heaps of waste that municipalities have to deal with.

Some of that waste – in particular plastics, metals and paper – is supposed to be recycled.

Yes, but a lot of waste is still going to landfill or is simply burnt. And that waste can be used in order to produce gas – which is called gasification of waste. Cutting-edge gasification technologies can effectively process a very wide bandwidth of wastes, including municipal waste.

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Returning to renewable gas, it’s also about hydrogen, right?

Yes, this is the less well-known area of renewable gas – hydrogen and synthetic methane.

You can use the excess electricity of wind and solar that would have to be curtailed otherwise at times of oversupply to split water molecules into hydrogen and oxygen. And then you obtain hydrogen as a gas. This is called “power-to-gas”.

It is a very energy-intensive process, but if you have excess electricity, why not put it to good use? And there are times when the electricity is very cheap – the price can even be negative. And then it makes sense to use that electricity to produce hydrogen.

Hydrogen can be injected into the gas grid to a certain extent, which is a drawback. There are studies underway to establish how much can go into the grid without causing problems with household appliances, like your gas burner.

At the moment, there is a consensus that about 10% of hydrogen in the gas grid would be very safe. So you could operate your appliances normally – whether for cooking, heating, etc. However, there is an ongoing project in Leeds to change the entire natural gas grid to hydrogen.

Synthetic methane goes one step further. You can make that hydrogen react with CO2 – and you can use the CO2 out of the air or from industrial processes. You combine the H atoms with the C atoms of the CO2 molecules and you get CH4, which is methane. And that way you are producing synthetic methane which has exactly the same composition as natural gas.

How energy-intensive is this process?

Producing synthetic methane is also relatively energy-intensive, so you would lose efficiencies doing it. But at the moment, this is the only large-scale and seasonal storage of energy available. Batteries are being developed. But there is no development in sight at the moment that would allow electricity to be stored in a battery on a large scale over a longer period of time.

For example, you can balance seasonal differences in heating demand with synthetic gas. In winter, demand for heating can be five times as high as it is in the summer. The gas grid can deal with that. But if all heating was electric, you would have a problem because the electricity grids cannot cover these fluctuations. On the other hand, if you have used the excess electricity to produce synthetic methane, you can use that to heat your home when it’s particularly cold.

So that’s the main upside, renewable gas can be used as a backup for renewable electricity.

It would become more than a backup. It would become a renewable fuel in its own right, which forms an interface with the electricity sector. And that’s why it is so important to have sector coupling – looking at the electricity in connection with the gas grid to see how the two can best interact.

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What is the current market share for renewable gas? And how much do you see it developing in future?

We have about 18 billion cubic meters of renewables gas at the moment – most of that is biogas – in a gas market of about 450 bcm. So that makes about 4%. It’s very small, it’s a technology that is still under development, let’s not forget that. But the potential is huge – whether for biogas, synthetic gas or hydrogen – and we need to develop that potential.

Assuming your expectations are met on the policy side, can renewable gas ever replace fossil fuel gas?

We asked E3MLab at the University of Athens to use the PRIMES model in order to do a scenario study on renewable gas. And they came up with a scenario where, in 2050, there would be about the same demand for gas as today, but 76% of that gas would be renewable. So that is the potential they came up with.

Is this a realistic projection or is it theoretical?

At the moment it is a theoretical figure because we are talking about a distant time-horizon. But if the framework is correct, this is thinkable, it is a scenario based on realistic assumptions.

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How can EU legislation help increase the share of renewable gas? Does the proposal to revise the Renewable Energy Directive meet your expectations in this regard?

It is helpful in the sense that Commission proposed that guarantees of origins are now also discussed for renewable gas. But there are also some gaps. For example, a level playing field would need to be created with respect to subsidies.

And we’re talking about much less subsidies than renewable electricity has received. For example in Germany in 2000 the subsidy for photovoltaic was up to €500 per megawatt-hour, and power-to-gas today would require a subsidy of around €130/MWh. So although we need the support to do research and development on renewable gas, the subsidy would be much less than for renewable electricity in the past. And we could see the same learning curves for renewable gas that we have seen for photovoltaic.

So equal treatment between renewable electricity and renewable gas is something we see as necessary. And there are little bits and pieces missing in the treatment of renewable gas – not just at EU level but also at the national level.

For example in Germany, if you produce synthetic gas through power-to-gas, you have to pay all the taxes and levies that apply. So you buy the electricity, paying the grid fee, energy tax, renewables charge and concession fee. That is quite a big chunk of cost that renewable gas has to face today.

Do you see the market driving down costs naturally in future? If there are so many advantages to renewable gas, why doesn’t the market do its magic, without regulatory support?

What we’re asking for is equal treatment with renewable electricity. So we’re not asking for special regulatory treatment for gas. And as I mentioned before, we’re asking that the electricity and gas grids are considered in combination.

How much would that require in terms of infrastructure upgrade and investments?

Not much at all. Because you take the electricity out of the local grid, run it through the power-to-gas plant and the gas goes straight into the existing gas grid. So all it needs is a power-to-gas plant and a connection to the gas and electricity grids.

And in places like Northern Germany where there is a lot of wind, this is where there are the best synergies for building a power-to-gas plant. Power-to-gas started in Germany in fact because of the push for wind and solar energy, which have created excess electricity. But it is now also being developed elsewhere, in Italy and Switzerland for example.

Germany also has issues with the transmission of electricity from North to South. The South cannot benefit from the wind that is produced up North unless large interconnectors are built. And there is local resistance to building interconnectors. So there is a role for power-to-gas there.

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Is the industry ready to make a commitment to raise the share of renewable gas, assuming you get the necessary policy backing?

It’s a matter of economics. If you have a reasonable return on your investments, you go for it, it’s very simple.

In terms of targets, there is already a renewable target at EU level and national renewable targets up until 2020. And renewable gas can contribute to achieving those targets. In the Netherlands, for example, 30% of renewable energy is actually biogas.

And at EU level, can you give an assessment of the potential of renewable gas to the EU’s overall renewable energy target for 2030?

That is difficult to say. The overall potential is big. You would need to work it backwards to see the conditions that are needed. The time-horizon for a large-scale take up of renewable gas would be 2030-2050.

But don’t forget that natural gas is the fossil fuel with the lowest CO2 emissions. And there is a lot you can do as well by replacing coal with natural gas. If you just increased the running hours of gas-fired power stations, most of which are not running much at the moment, you could actually exceed by 2030 the EU’s 40% greenhouse gas reduction target by 6%. And that would just be based on using more natural gas than coal – without replacing coal completely.

So that’s why our horizon is long-term – we can achieve a lot at lower cost by first replacing coal with natural gas and then increasingly adding renewable gas to the natural gas.

Biogas or biomethane could run into similar environmental issues as biofuels when it comes to land use change, food prices, or deforestation. Have you given some thought to these issues?

We are focusing in particular on making use of waste rather than arable land, or forests. So we don’t have the same issues.

At some point, you will run out of waste, however.

You won’t run out of waste because you will always have agricultural waste, municipal waste, or animal waste. We’re a wasteful world.