Denmark needs more organic production. Much more. A majority in the Danish Parliament agrees, and this was also stressed in the Agricultural Agreement signed back in 2021, with a goal to double the area of organically farmed land by 2030. However, if we are to have any chance of realising that goal, we need clover grass. Lots of it. And more biogas.

This is according to Henrik Bjarne Møller, a newly appointed professor at Aarhus University's (AU) Department of Biological and Chemical Engineering. Henrik Bjarne Møller has been a biogas pioneer since the technology was in its infancy.

"The problem is that we don't have enough organic nitrogen," he says, and continues:

"Organic farming is dependent on nitrogen, but there simply isn't enough organic nitrogen to push the development required if we’re ever to come even close to doubling the area of organic farming. Clover harvested for biogas is the biggest source of nitrogen to drive organic farming forward, but we need to get started now if we want to reach our goal in about five years."

Organic farming growth has stagnated

Henrik Bjarne Møller is co-author of the knowledge synthesis published in 2023 by ICROFTS, the International Centre for Research in Organic Farming and Food Systems. The report forms part of the basis for work by the Ministry of Food, Agriculture and Fisheries on preparation of its organic strategy to support a doubling of the area farmed organically and to promote organic products.

Today, organic agricultural land amounts to 303,563 hectares or 11.4 per cent of the total agricultural area in Denmark. That area has to reach 510,000 hectares by 2030. But growth has stagnated, and one of the main reasons is that there is not enough organic nitrogen for such a massive expansion.

"Nitrogen for organic farming today comes largely from conventional animal manure. Phosphorus and potassium, which are also necessary for efficient farming, can be sourced outside of conventional agriculture, but nitrogen is more difficult. As far as we can see, the only way forward in this context is clover grass" says the professor.

Low-hanging fruit in the organic transition

Clover is a legume, and the pod absorbs nitrogen from the atmosphere then turns it into protein. The tops of clover contain at least half of the plant's absorbed nitrogen, and if you harvest the tops and use the biomass in a biogas plant, the degassed product will contain all the nitrogen, which can then be spread on fields as 100% organic fertiliser.

The part of the protein that can be digested and used by monogastric animals can be extracted in the protein refining process to create even more value from the grass.

At the same time, we can also convert the plants into biogas for green energy and other high-value products. The roots stay in the soil and retain nitrogen and carbon, thus improving the soil and providing fertiliser for crops.

"We know that this works. Lots of field trials have been done and the entire knowledge base is in place. This is the absolute lowest-hanging fruit to increase the area of organic farming. But biogas plants are not yet fully equipped. There are only a few organic biogas plants in Denmark, so this transition requires people with courage to take the plunge and see the financial incentive," says the professor.

Climate and environmental benefits

Biogas is a green source of energy and it plays an important role in the green transition because biomethane can replace fossil natural gas. Almost 40 per cent of the gas in the Danish gas system was biogas in 2023, and by 2030, 100 per cent of Danish gas consumption is expected to be biogas. To achieve this ambitious goal, straw and grass in particular need to be much more widespread in fertiliser-based systems or in purely plant-based systems.

"Denmark is a leader in both agriculture and biogas, so going this way makes sense," says Henrik Bjarne Møller, and he continues

"There’s a huge amount of knowledge development and expansion going on in the field. We’re working with completely new processes using hyperthermophilic microorganisms that are far more efficient so we can run biogas plants exclusively on straw and get far more biogas. Grass and straw offer huge perspectives for the biogas sector, and both have major climate and environmental benefits."

About the professor

Henrik Bjarne Møller was born in Skallerup and grew up in Vendsyssel. He spent part of his childhood on the island of Læsø. He developed an early interest in agriculture through his grandfather, who had a large machine business in Hjørring that sold IH tractors and combines.

He then applied to the Royal Veterinary and Agricultural University, from where he graduated as an agronomist in 1990. As a student, he became interested in biogas, which at that time was only at grassroots level. He was the first student at the university to write a thesis on biogas and the agricultural and environmental consequences of using animal manure and organic residues in biogas plants. 

After graduating, he worked in Herning for a number of years running, optimising and establishing biogas plants.

"It was a pioneering direction back then, and we demonstrated for the first time that biogas plants could utilise organic household waste and animal manure together. A lot has happened since then, and biogas is a big part of the agenda today," he says.

He was also employed at the consulting engineering company Niras for a number of years, where he worked with local farmers and urban communities on building biogas plants, before taking his PhD at the Technical University of Denmark (DTU) and joining the Danish Institute of Agricultural Sciences before it merged with AU.

Henrik Bjarne Møller was the first researcher at AU to work with biogas. Today, he leads a research group dedicated to biogas at the university's Department of Biological and Chemical Engineering.

His research is primarily at the university's research centre in Foulum, AU Viborg, where world-leading research in livestock, plants, ecology, bioenergy, environment, climate, soil, genetics and technology merge, and where the focal point is development of circular, bio-based production systems to replace modern society's dependence on fossil resources.

Henrik Bjarne Møller will give his inaugural lecture on 17 January 2025.

Contact

Professor Henrik Bjarne Møller
Aarhus University, Department of Biological and Chemical Engineering
Mail: henrikb.moller@bce.au.dk
Tel.: +4540531596