7 questions about biomethane (green gas)

As an end product, biomethane is the same as natural gas. There is no difference using it in a gas hob or boiler, or in cars that run on methane gas. ‘Bio’ only says something about its origin: it’s produced through anaerobic digestion of natural waste streams, such as manure, agricultural waste, pulp, roadside grass or organic waste. Anaerobic digestion of this generates biogas. This biogas is purified, because it contains too much CO₂, and is then injected into the natural gas network. All biomethane is currently produced through anaerobic digestion. There are a few hundred digesters in the Netherlands and about 90 parties that turn it into biomethane.

In addition, work is underway to develop a new technology: gasification. Under high pressure and temperature, both wet waste streams (e.g. sewage sludge) and dry waste streams (e.g. timber waste or old IKEA cabinets) can be converted. This produces synthetic gas. After purifying and enriching this gas, it has the same quality as natural gas. 

In the energy transition, we’re working on ensuring clean and affordable energy for everyone, for both industry and households. In many cases, biomethane is the cheapest sustainable alternative to fossil natural gas. It’s already available and you can also produce biomethane all year round and store it underground, so you have reserves for periods without sunshine or wind.

All-electric heat pumps and heat networks are great solutions, but they’re not always suitable for old city centres and sparsely populated rural areas. If you can’t construct a heat network, you can supply biomethane. And in places where the power grid can’t be upgraded, biomethane is a sustainable alternative. In addition, biomethane can be combined with a hybrid heat pump.

Biomethane is home-grown energy, making us less dependent on other countries. And it allows us to do useful things with residual waste, which would otherwise be incinerated. Anaerobic digestion recovers 55% of the energy you invest in producing it. Gasification is even more efficient, achieving percentages of 70-80%.

View the animation about biomethane:

There are many producers of biomethane. How do they guarantee that their gas is truly green? There are certificates for this and producers are unable to sell their gas without a certificate. Two kinds of certificates are available:

• Verticer is the certifying body in the Netherlands that issues Guarantees of Origin. These are used to prove the origin of the biomethane. The Guarantee of Origin states when you produced a certain quantity of biomethane and what the percentage of organic material is. You can’t sell biomethane without this Guarantee of Origin. Gasunie is one of the partners in Verticer.
• Internationally you have ISCC (International Sustainability and Carbon Certification). This is an international standard for which you need to pass an audit. ISCC issues Proof of Sustainability, which is used to prove how much you save on carbon emissions. You need this certification if you want to sell the biomethane abroad, for example.

The ambition in the Dutch Climate Agreement is to produce 2 bcm of biomethane per year by 2030. Biomethane production in 2024 totalled 294 million cubic metres. This represents a 5% growth compared to the year before and is somewhat disappointing. Among other things, it was caused by the high price of biomass and the fact that a number of digesters were not operational for a while. This pushed the cost of producing biomethane past the revenue it generates.

Many small digesters are expected to start operating over the upcoming period and larger projects will also be joining in. However, we need four times the numbers, and that’s a major challenge. Agreements with the government should help move things forward. A biomethane blending obligation will be imposed on energy companies. If the bill is passed by the Dutch House of Representatives, energy companies will have to purchase and supply a growing percentage of biomethane from 2026, up to 20% in 2030. That’s about 1.1 bcm, which encourages producers to scale up. At the same time, we need a breakthrough in gasification technology. To achieve this, Gasunie is working together with other parties on developing the gasification installations in Alkmaar.

Yes, biomethane can make use of the same pipelines as natural gas, as it’s purified to match the product quality of natural gas. The challenge lies in the pressure levels during transport through the pipelines underground. The main and regional transport networks, which are managed by Gasunie, are under high pressure (around 66 and 40 bar). The low-pressure networks managed by the regional network operators are under 8 bar or less. Production of biomethane is quite constant throughout the year, but the demand varies. One example is during summer, when homes don’t need much gas, so you may have too much then. The biomethane, which may have been produced in a digester on a farm, will then have to be pumped from a low-pressure network to the national transport network. This requires a booster, which increases the pressure of the biomethane. 

View the animation of how a booster works:

Local and provincial authorities draw up regional energy strategies, which describe things like how they want to move away from (grey) natural gas. It’s important that they designate locations for digesters or gasifiers and accelerate the licensing process for these. It would be useful if those locations were close to a regional natural gas network.

Absolutely. A farmer can greatly reduce the amount of ammonia released by quickly getting manure out of a barn or from the land and into the digester. You can treat the residue that remains after digestion, the digestate, in what is called a nitrogen stripper. You can also process the digestate into another product, such as soil improver, and transport that to locations where you need it. As a final measure, you can add a plant-based product to the manure that stays behind in cellars. This makes the manure more acidic and reduces ammonia and methane emissions. The methane no longer escapes into the air and less nitrogen is released. These solutions allow you to reduce nitrogen and methane emissions by double-digit percentages. The biomethane blending obligation could ensure that this is accelerated, as it becomes more interesting for farmers to invest in such solutions.