Around 9,000 biogas plants, with an installed capacity totalling some 4.2 GWel, are in operation in Germany. The electricity they generate currently covers 5 per cent of gross power consumption throughout the country. A fleet of plants whose longer-term future remains uncertain, however. Prof. Dr.-Ing. Christof Wetter, of the Münster University of Applied Sciences, summarises the most urgent challenges facing the sector.
Professor Wetter, what developments are forcing biogas-plant operators to take action?
The now terminating RESA payment confronts every biogas-plant operator with the question of how the future of his or her plant will then look. An examination of the subject at an early stage appears necessary, against the background, also, of the adjustment of other legal boundary conditions, such as the Fertiliser Ordinance, for example, and growing cost pressure, in the case of substrates, for instance.
Could these changes also in fact be an opportunity for the biogas industry, or rather the power and heat system?
Yes, provided spaces for creative innovation are also implemented. Consistent further evolution of concepts for needs-orientated supply of electricity and heat from biogas plants offers great opportunities, for example. Here, biogas can play an important role, as balancing energy and as a grid stabiliser. Not least important is the fact that biogas can be stored, and can also be transmitted via the existing gas grid, after preparation.
What, in your opinion, are the most important adjustments for plant operators?
There is a whole series of potentials for optimisation along the biogas process chain. Breakdown efficiency, for example, can be boosted by pretreating substrates, or by systematic use of additives. The greater use of residues, and plant technology optimised for this, and optimisation of digestate utilisation for closed nutrient cycles, offer even more potentials. The utilisation of the biogas generated has a significant influence, above all, however.
And what future-viable business models do you perceive for plant operators?
Primarily in smart heat-utilisation concepts and demand-regulated supply of electricity, via balancing and standby energy for example. An important key to future-viable business models can be found here, in my opinion.
Do you see any alternative utilisation concepts for plants which can no longer be operated cost-efficiently?
There won’t be all that many opportunities for these plants. The tanks can, of course, be used for storage of liquid manure, and the CHP units can, in some cases, also be operated using fossil energy sources, but there will, no doubt, in many cases be a decrease in plant numbers. From a political viewpoint, however, it will be necessary to ask whether the concomitant squandering of assets can really be desirable. There are no less than 9,000 biogas plants, and thus companies, in Germany that have made an important contribution to the energy turnaround, and can continue to do so. Especially when you remember storage potentials, balancing of peak loads, sector integration, alternative fuels and the replacement of natural gas in the grid.