This in turn is subdivided into various levels:
The use of biomass for obtaining energy has a large sustainability potential, because in principle it is beneficial to the reduction of greenhouse gas emissions, in particular CO2 emissions. The reasons for this are to be found, quite literally, “in the nature of things” – their basis are the biochemical connections underlying the emergence of biomass and its transformation in terms of energy, as examined in Biomass - biochemical basics. However, these principles are sometimes undermined if generating and processing the biomass itself entails a major expenditure of energy (covered by fossil-based sources) or if, in order to create space for the cultivation of the biomass, jungles are cleared and swamps are drained, thereby releasing large quantities of greenhouse gases. Under some circumstances these quantities are greater than the savings of no longer using fossil-based fuels. As a consequence, the use of bioenergy must match certain framework conditions that need to be critically challenged and monitored continuously.
Diversity of species
The same applies here – subject to having the right framework conditions, bioenergy has the potential to contribute to the diversity of species. After all, the wide range of energy crops and other renewable natural resources is significantly greater than the current, rather limited spectrum of plants used for food and animal feed production. This range is by no means fully tapped; on the contrary, up to now most “energy farmers” are concentrating on high-yield crops that they know well and for which they have the suitable cultivation and harvesting techniques: maize, rapeseed, grain. And yet the change has begun: for instance, the German Renewable Energy Sources Act (EEG) has stipulated that farmers in Germany are not permitted to use only maize in their biogas plants, brought into service in or after 2012, if they wish to continue to get the remuneration established in the EEG. Much urgent effort is being directed into research work on new energy crops. And many farmers are already interested in trying out new things on their arable land.
One thing is clear: the use of bioenergy needs legislative framework conditions, research and development, a functioning transfer of knowledge from research into practice, and farmers who implement new findings from research – then there is nothing more standing in the way of a diverse agricultural landscape, which apart from producing food and animal feed, also generates other raw materials and energy.
A wood heating system emits more particulate matter than a gas-powered heating system does, but biodiesel is less hazardous to water than fossil-based diesel. A non-covered post-digester used in a biogas plant releases ammonia, but so does a conventional slurry container. Other examples could be listed making the same point. Conclusion: again, reality is not a black-and-white matter. As a general observation, biomass is less toxic and hazardous to the environment than fossilbased natural resources, but in a particular situation the issue is always HOW it is being used. Yet here also, through technical development and appropriate framework conditions, sustainability can constantly be further enhanced, step-by-step – thus, for example, modern wood-fuelled heating systems are emitting much less particulate matter and due to what by now is the legally-binding obligation in Germany to seal the postdigester gas-tight, the ammonia emissions from biogas plants are prevented to a large degree.