How to triple the biogas production by 2030 through sustainable biomass

Jens Bo Holm-Nielsen, Center for Bioenergy and Green Engineering, Aalborg University, Denmark

The European biogas platform looks promising and expanding by 2030 and further beyond.

For biogas generation we do not need to focus any more on energy crops from croplands suitable for food and feed production. The focus should rather shift to byproducts from primary agriculture and animal manure, including deep litter bedding materials. In the primary agriculture sector, a huge amount of straw products can be supplied as byproducts from grain production. Using straw for biogas has not been an easy task in the past, as its dryness and the presence of lignocellulose make straw a complex feedstock. But thanks to research and technology developments occurred over the last 5-10 years, we have learned to overcome these barriers, mainly by good pretreatment routes: notably, by mechanical pretreatment, long retention time and recycling between the digestion steps. Straw adds valuable total solids and volatile solids carbon sources to the anaerobic digestion process, leading

to an increased, higher and more stable production. Another large-scale feedstock resource comes from grassland products of multiple kinds from permanent grassland areas. Based on European and FAO land use statistics on agriculture land, large areas registered as farmland are permanent grasslands of various kinds in almost all European countries. Besides being used for grazing purposes and haymaking, these areas exists to maintain good and high-quality biodiversity and ; similar regulations of these areas can be used for biogas feedstock. There is a steady but constant tendency in decreasing the number of ruminants for meat production, so anaerobic digestion for biogas production and for biorefinery routes, can be seen as a supplementary and new way to use those permanent grassland areas, and as a good alternative or supplementary source of income locally. On this basis, our GIS mapping and studies shows that the biogas production level can be tripled by 2030 without compromising sustainability. Hence, the European biogas sectors should make use of food waste, food-processing waste and all kind of quality-ensured organic waste and byproducts. For each area and region, sustainable biomass should be mapped before new biogas projects are getting started. The sustainability and availability of cheap carbon sources should be documented and available in each region and almost everywhere, therefore such biomass resources are available in large numbers.

BIOMETHANE IN THE EUROPEAN GAS GRID

The European biomethane green gas distribution and gas markets are emerging rapidly over these years. The recent mapping from the European Biogas Association (EBA) and Gas Infrastructure Europe (GIE) shows a remarkable growth in number of biogas upgrading facilities during the years 20182020, with installations in new EU countries each year, and it is estimated that the green gas platform can increase 10-15 times in volume by 2030.

Green gas plays a very important role in the green transition of EU, to reach the COP-15 1.5 – 2.0 °C climate goals, and to create a fossil free Europe, fully developed and integrated by renewable energy systems and energy efficiency measures.

GREEN GAS PLAYS AN IMPORTANT ROLE ALSO IN COMBINATION WITH WIND AND SOLAR ELECTRICITY

The figure 1 by Evida, the national Danish Gas distribution company, gives a glimpse of the rapid growth of green gas. In early 2020, the share of biomethane

Figure 2 - Nature Energy Biogas plant Korskro in Denmark. It is currently one of the biggest plants in Denmark and in the EU, using 710.000 tons of biomass per year (85% residues from agriculture, 15% Municipal and Industrial Residues), from almost 100 farmers and suppliers associations. It produces 22 mio. m3 green CH4 per year.

in the gas grid in Denmark was 11% on average, then in March 2021 it reached 21.5%. It is stipulated that by 2040 green gas will take over the full gas grid capacity.

BIOGAS-CO2 FOR METHANISATION AND PTX WITH WIND AND SOLAR SCALE-UP CASES

Biogas is moving fast for the integration in the European gas grid, notably for the methane part. Large-scale industrial use, strong gas grid infrastructure, large-scale renewable energy systems as well as the integration with electrifications of society is on the agenda for 2030 and beyond. However, we need to address and get full use of CO2, which is approximately the 40%. of biogas. CO2 can be used directly for methanisation, to get a higher production of methane during the anaerobic digestion process. Another route of CO2 use consists in the upgrading and separation process to clean the CO2 to obtain industrial green CO2. One case example is established at full scale at the Nature Energy Biogas plant “Korskro” nearby Esbjerg, Denmark. Approximately 1/3 of all industrial CO2 utilized in Denmark has its origin from this biogas plant.

In the European hydrogen context, CO2 gas cleaning and upgrading

has a much wider purpose. In this decade, project by project new electrolyzing capacities from large scale solar and wind farms are being installed. Large scale offshore wind farm systems in the North Sea region are established, and power-to-X (PtX) on artificial islands projects are in the pipeline. In conjunction with the large scale solar and wind installations, the biogas and green gas infrastructure comes in as one of the best options for producing methane, methanol and other electrofuels for the transport sectors: shipping, trucking and aviation need large quantities of concentrated liquid fuels, where these PtX solutions are part of the equations and forecasts. Several projects in the PtX context are under testing and scaling up phases in Europe.

Figure 3 - Loading of lignocellulosic feedstock at Nature Energy biogas plant.

Finally, there is a healthy competition for moving our societies towards a further CO2 reduction, into a green era of decarbonization and a more climate acceptable future, but much remains to be done in the next one to three decades.

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