When the grid is full: where does biomethane go in summer?

There are two ways to deal with a summer surplus. You can keep the gas in the grid by compressing it up from the local distribution network into the high-pressure transmission grid, from where it can be transported to places where there is still demand. Or you can keep it out of the grid, by liquefying the biomethane on site into bio-LNG and moving it by truck to where it is needed. Both solve the same problem, and they cost roughly the same.

Both routes also have real advantages, and both deserve to be chosen on their own merits. But one factor lies outside those merits and quietly tips the balance: the way in which they are financed. The grid route is largely paid for by the network operator, who then spreads the costs across everyone via the tariffs we all pay. On-site liquefaction is paid for exclusively by the biomethane producer. When one option is collectively funded and the other is not, the collective option has a natural advantage, regardless of the merits of both.

On-site liquefaction solves the same problem of summer surplus, at a comparable cost. At Nordsol we see that an installation able to liquefy biomethane costs around the same as a booster, while handling two to three times the gas volume. Add to that a storage tank, plus the costs of transporting the fuel by lorry to the customer, and the total cost per unit of gas is still lower than that of a booster.

The difference lies in who bears the costs. On-site liquefaction is funded almost entirely by the biomethane producer. The network route is not always unconditional either: in Ireland, a developer now pays around 370,000 euros⁸ towards reverse compression on top of the standard charge, and in Germany, new rules¹⁰ let grid operators cap injection capacity when infrastructure security or economic efficiency requires it. Even so, on-site liquefaction still receives almost no shared support across most of Europe.

The two products (gaseous and liquid biomethane) are also suited to different applications. Gaseous biomethane in the network is mainly used for heating homes and buildings. Liquefying biomethane produces bio-LNG, the renewable liquid fuel that heavy long-distance road transport and shipping actually run on. These are some of the most difficult sectors of transport to electrify, and exactly the segments that EU legislation like RED III and FuelEU Maritime are pushing to defossilise.

None of this is an argument against grid injection. Boosters and rebours stations fulfil an important function, and the networks that pay for them make renewable gas available that would otherwise be lost. The point is about balance. For a summer surplus the local grid cannot absorb, on-site liquefaction is a solution with comparable costs that also delivers a fossil-free fuel directly to the transport sectors that are the most difficult to make sustainable. Yet this option is rarely put forward alongside the grid route, and rarely supported in the same way.

We can already see what shared support can achieve. In Sweden and Norway, where bio-LNG for transport has long had public backing, the route has developed much further than elsewhere in Europe. Sweden supports it from both sides. Its Klimatklivet climate investment programme puts public money directly into biomethane production and liquefaction plants¹¹, and the country also exempts biomethane used as a transport fuel from energy and carbon tax.

The effect shows in reverse, too: when Sweden briefly withdrew that tax exemption¹² in 2023, biomethane became more expensive than fossil fuel almost overnight, and many biogas investments were put on hold. Correctly dosed support ensures a level playing field, and at present that playing field is not level across most of Europe.

The production of biomethane is set to increase significantly by 2030, and the summer surplus will grow accordingly. The question is not whether the gas network can cope with all of this, but whether both solutions will be given a fair chance, so that nothing is wasted.