Biogas is an important contribution to our future energy supply – and the future is now! Together with wind and solar energy, biogas plays a decisive role in the green transition with the phasing out of fossil fuels in favor of renewable and CO2-neutral energy sources. And only when the biogas plants are supplemented with storage or PtX, full potential be achieved, allowing us to speak of a fully circular economy for future energy supply.

Biogas is a green gas that both solves difficult climate challenges, contributes to an independent supply chain and makes food production more sustainable. Today, more than half a million tonnes of CO2 is captured on an annual basis in Denmark during the upgrading of biogas to natural gas quality – a number that is expected to increase considerably over the years to come. And there are several good reasons for this to happen.

CO2 from biogas is both cheap and readily available. In addition, CO2 from biogas is a very clean CO2 that exists in concentrated form and with minimal need for pre-treatment prior to compression and transportation. And because of this biogas suppliers are also expected to contribute significantly to the climate effort. The question is not whether, but how biogas will have an effect on the climate effort and by what timing and impact. Decisive for this development will be the given framework conditions, but also the demand for green fuels.

About Biogas

Biogas is a gas consisting of methane and CO2, which is formed when organic material rots under oxygen-free conditions. This is a natural process that the biogas plants use to degas food waste, straw, animal manure and residual products from agriculture and industry.

The biogas is either distributed to customers via the gas network or used for the production of green electricity and heat. The biogas fed into the gas network is used by industry and heavy transport, among other things. The majority of Danish biogas production is currently distributed via the gas network. The biogas that comes out of the biogas reactors contains approximately 55-65 percent methane. The rest is CO2, which is cleaned out of the biogas before the green gas is fed into the gas network. CO2 from biogas is fossil-free and originates primarily from animal manure, waste and residual products from industry and households.

There are currently around 190 biogas plants in Denmark, with a total biogas production of approx. 800 million cubic meters. In 2022, the Danish Biogas production marked a new record and covered 40% of total gas consumption.

Source: biogas.dk 

Biogas for storage or PtX?

One of the major challenges regarding biogas is when the organic matter is not fully utilized for energy. But there are solutions to this. CO2 from biogas can either be stored in the underground or bound further in a PtX food chain, in combination with hydrogen for the production of the fuels e-methane or e-methanol, to displace fossil fuels and intended for various areas of application, e.g. heavy transport.

The path of biomass to storage/PtX.

According to the Danish Energy Agency, biogas is by far the cheapest source for getting carbon into PtX green fuels, which is due to its here-and-now availability plus the simplification of processing it. Conversely, storage is seen in the underground, e.g. The North Sea, also as an obvious option.

In previous analysis and on the basis of projection forecasts from the Danish Energy Agency, Biogas Danmark has looked at the various positive climate impacts that biogas can have if stored or converted in PtX into green fuels. Likewise, Biogas Danmark has assessed the potential considering the timing of scenarios. According to the projections from the Danish Energy Agency and the conclusions based on that from Biogas Denmark, the greatest potentials for reduction in CO2 emissions are found in PtX and in the displacement of fossil diesel.

Availability of green power, public support for the solutions, market prices for electricity as well as the demand and price of PtX fuels compared to CO2 storage are all factors that will play a role in relation to the use of CO2 from biogas in the years to come.

Clima impacts, Storage vs. PtX

Climate effect of storing CO2 in the North Sea

If biogas production develops as expected in the Danish Energy Agency’s latest forecast, Danish biogas plants will be able to contribute by an additional CO2 reduction of approximately 1.5 million tonnes of CO2 in 2030 providing the CO2 from the biogas plants is stored. This reduction comes on top of the greenhouse gas reduction of 3 million tonnes, which already comes from a biogas production of 52 petajoules according to the Danish Energy Agency’s latest projection.

Climate effect of e-methane and e-methanol

If all the CO2 from the biogas plants is instead combined with hydrogen from green power to produce e-methane, it will be possible to achieve a production of 27 petajoules of energy, which will reduce CO2 emissions by a little more than 2.4 million tonnes in 2030 in the displacing of fossil diesel.

If the CO2 is instead used for the production of e-methanol, according to Biogas Danmark’s calculations, it will provide an energy production of 21 petajoules in 2030 with a CO2 reduction of more than 1.9 million tonnes, also by displacing fossil diesel.

Source: https://www.biogas.dk/skal-co2-fra-biogas-bruges-til-power-to-x-eller-lagres-i-nordsoeen/

Case-by-case

With the possibilities for CO2 storage and PtX, many Danish biogas players are currently looking into the future perspective of scenarios around storage and/or PtX. There is much to be gained by making the right decisions, and paths opening up to both more than one just one scenarios and timing to pursue.

Each individual biogas producer will need to make most fit decisions in relation to business model and investments. The biogas producers need to clarify financial overviews of investment and returns in order to decice on most fit direction. The location of the biogas producer in relation to existing infrastructure, the producer’s current and projected capacity and a given investment in that light combined with a look into scenarios for electricity pricing is interesting to consider. The latter, electricity prices, is an element highly variable, but with the help of various simulations, it is possible to zoom in on Capex and Opex in different scenarios, helping biogas producers to better decide.

The Illustrations show the simulation of methanol production against the background of a biogas plant’s production of CO2. In simulation, the values can be adjusted and, on that basis, potentials for several scenarios can be projected. The figures from such simulations combined with CapEx and OpEx over time, which can be 10 years or more, give the biogas supplier a clear overview to be able to make decisions about investments and tracks to follow in relation to operating capacity.

Sindal biogas in North Jutland, Denmark, is an example of a Danish biogas player that is currently looking into the possibilities of using CO2 from biogas production for e-Methane or methanol. Sindal Biogas handles approx. 200,000 tonnes of biomass per year and produces around 20 million cubic meters of biogas. In facilities next to the existing biogas plant, they plan to build the PtX plant, which will capture CO2.

“- We believe that capturing CO2 in the long run can form a significant part of our business, in levels matching our existing production of biogas”, says Morten Glenthøj, business developer for Sindal Biogas.

John Kjær – Head of Sales and Business Development Hydrogen Valley: “If we are to succeed with the green transition and with biogas making a difference, it is absolutely essential for biogas producers, who will drive the development, to have access to the right data and knowhow on both climate impacts and the financials aspects. In the opposite case, they will fail to invest, and Denmark will miss out on becoming a pioneering country within the area, similar to the competitive edges currently gained globally by our wind industries.”