In the form of firewood, fuel or biogas: a great diversity of energy media can be obtained from biomass. Bioenergy, as a regenerative energy form, is a key pillar in the energy mix of the future. Attention is now shifting to the efficient use of plant residue, in order to avoid competition with food production. Exploiting the potential of sustainably cultivated energy crops, and promoting innovative process technologies – these are important steps in the bioenergy sector.
FACTS & FIGURES
No. of companies:
(Source: Federal Statistical Office)
Examples of bioeconomy:
Wood-pellet heating systems, biogas, biodiesel, bioethanol, synthetic biofuels
Biomass – plants as well as plant and animal residue and waste – is valued among renewable energy carriers for its versatility: it can be used to produce heat, electric power and fuel. Wood fuels are typical for solid bioenergy carriers: for example, wood chips and shavings and wood pellets. Liquid bioenergy carriers include biofuels such as plant oil, biodiesel fuel and bioethanol. Biogas and biomethane constitute the gaseous energy carriers. In addition to the great diversity and flexibility of biomass, there is an additional benefit: biomass can be stored, and bioenergy systems can be flexibly controlled. As a result, they offer the potential of compensating for the fluctuating availability of other regenerative energy sources such as wind power and solar energy.
According to data from the Working Group on Renewable Energy Statistics (AGEE-Stat), Germany in 2013 covered 12.3 % of its final energy consumption with renewable energy. Bioenergy, with a share of 62 % of renewable sources, represented the greatest renewable contribution. As a share of final energy consumption, bioenergy covered 7.7 %. Currently, bioenergy is especially widely used for heat production: of bioenergy used in Germany, 36.7 % is used in the form of heat. For provision of heat, biomass is by far the most important regenerative energy source: it supplies approximately 80 %. In the electric-power area, biomass is the second most-important source of renewable energy: it provides 8 % and ranks second only to wind energy.
With its energy transformation (Energiewende), the federal government intends to increase appreciably the share contributed by renewable energy. Its objectives are for 55 to 60 % of electric power to come from renewable energy sources by 2035 and for 80 %, by 2050. In addition to wind, water and sun, bioenergy represents an important building block toward this objective in this energy mix. Energy from regenerative raw materials supports climate protection: when biomass burns, it releases exactly as much carbon dioxide as an equivalent sustain-ably produced plant has absorbed during its growth. Regenerative biomass in turn absorbs the released amount of CO2, which closes the circle. Economically, bioenergy contributes to regional value added and creates jobs in rural areas. This has become evident, for example, in the growing number of bioenergy villages and regions that have grown up throughout Germany.
At the Karlsruhe Institute of Technology, plant residue is transformed to synthetic fuel in a pilot plant.
The Renewable Energy Law (EEG), which regulates government subsidies for power production from renewable sources, has enabled vigorous growth in the German bio-energy sector over the past 14 years. This boom, however, has been accompanied by definitely problematic aspects. These include, for example, the fundamental danger that the use of biomass for energy will compete with the production of food and fodder, and with land areas that would otherwise be interesting from the standpoint of nature conservation. The enormous increase in cultivation of only a few energy-plant species – one-sided in some areas – can, in case of continued increases, have deleterious effects on ecosystems. An important objective is to attenuate the competition among fodder, food and fuel: for example, with a new generation of biofuels obtained from organic residues and waste materials, and not from plant fruit. In Europe and Germany, the pathways of using bioenergy are presently being re-evaluated and their basic conditions adapted as required. In 2014, the Renewable Energy Law was revised for the fourth time. The objective formulated by the federal government for the future will be to concentrate primarily on waste and residual materials in the use of biomass for energy. Concepts and technologies that enable innovative use of sustainable bioenergy will continue to be key points of interest.
Wood as raw material is of great importance as fuel. Around 60 million tons of wood are burned every year in Germany – chiefly as split logs in the ovens and boilers of private households. With financial support from the government Market Incentive Programme (MAP), the num-ber of automatically fed and low-emission wood-pellet and wood-chip heating systems has risen. To meet this demand, approximately 2.3 million tons of pellets and 6 million tons of wood chips, as regionally available biofuels, are sustainably produced annually in Germany. Around 90 % of renewable heat is produced from bio-mass, of which over 70 % originates from wood. In view of rising prices of fossil energy carriers, forest wood and wood waste offer previously untapped potentials for production of heat. Traditionally, wood has primarily served as supplier of heat. Single- and multi-family dwellings can today be heated cleanly and efficiently with wood-pellet systems. The advanced and fully automatic technology of pellet heating enables significant reduction in air-pollutant emissions such as fine dust and carbon monoxide. Large-scale wood power plants – often fired chiefly with scrap wood, over-matured wood, and wood residue from forests – simultaneously produce electric power and heat for communities and urban districts by means of cogeneration technology. Now, after technology for wood-gasification in combined heat and power plants (CHP) has in recent rears achieved market and series-production maturity, pellets and wood chips can also produce heat and power in smaller cogeneration systems.
In addition to used-wood markets and forests as energy-wood suppliers, attention also shifts to so-called short-rotation forestry, in which fast-growing trees such as poplars are planted. Once they are planted, their wood can be harvested every four years, and the trees produce new shoots. Such husbandry of wood crops, similar to permanent crop cultivation in vineyards, offers benefits over other energy crops with respect to climate protection and ecological compatibility. The Federal Ministry of Food and Agriculture (BMEL) promotes this field with many and various research and development projects.
Biogas plants transform energy crops, animal excrement such as liquid manure, and other residual materials into biogas. In airtight containers known as fermenters, microorganisms ferment biomass to a gas mixture, which consists primarily of methane and carbon dioxide. The resulting biogas is then burned as fuel in combined cogeneration plants (CHP), which produce heat and power. After fermentation, organic material remains and can be used in fields as fertilizer – which closes regional materials cycles. Some plants can also process biogas to biomethane. This process enhances the methane content and the quality of the biogas such that it can be fed into the natural gas network.
During the past ten years, the biogas sector has grown tremendously, driven by financial incentives within the context of the EEG. More and more farmers are additionally becoming “energy farmers”. According to the German Biogas Association, there were about 7,700 such biogas facilities in Germany in 2013, which produced 24 billion kWh of power. By far the majority of these plants are located in Bavaria and Lower Saxony. The relevant sector association has counted 40,000 workers who are employed in construction, operation and maintenance of such plants – as well as in cultivation of energy crops. Sales volume was approximately 6.6 billion euros in 2013.
Germany is considered the world leader in biogas technology. This sector, which extensively consists of small and medium-sized enterprises, generated around 40 % of its sales in foreign business during 2012. In production and process engineering there is still great potential for improvement, especially in interlinking of the individual steps. The main constituents, for example, in the fermenter – the bacteria and microbsial community at work there – have until now been insufficiently characterized. The BMBF funds a number of collaborative projects in the funding initiative known as Bioenergy – Process-Oriented Research and Innovation (BioProFi), which has addressed this issue. The development of sensors for measuring the fermentation process, and of catalysts for purification of biogas, involves additional aspects with which biogas researchers are experimenting. For years now, the BMEL has also dedicated one focus of its attention to increasing the efficiency of the biogas process. The biogas boom has indeed noticeably changed the face of agriculture in a number of regions: for example, by massively expanding the cultivation of maize as the most productive of energy crops. This, however, has not only restricted diversity, but has in some areas impaired the soil and environment owing to one-sided agriculture.
In biogas plants, microbes ferment energy crops and liquid manure to biogas.
Sustainable cultivation concepts for energy crops are therefore a key objective for research funding. The BMEL funds numerous projects to expand species diversity on fields dedicated to energy crops, and to optimize cultivation techniques. Methods considered include crop rotation with annual alternation, as well as companion planting. For several regions of Germany, energy crops adapted to certain locations have been investigated and confirmed as suitable: for example, sorghum millet, the sunflower, the cup plant (Silphium perfoliatum) and other wild plants that can be used as energy crops.
Biofuels support mobility, since they can be used to power internal combustion engines in automobiles, transport vehicles, ships and aircraft. Biofuels are presently the most important renewable alternative for energy- efficient transport structures of the future. In 2012 biofuels covered 5.7 % of German fuel consumption. With annual consumption of 2.2 million tons, biodiesel fuel in 2013 represented the lion’s share of the German biofuel market, whereby 1.2 million tons of bioethanol were marketed. It is possible to use biomethane without restriction as fuel in natural-gas vehicles.
Biodiesel fuel is manufactured, primarily from rapeseed oil, at over 30 production locations in Germany. By mixing bioethanol with super-grade petrol, it is possible to produce bio-based fuel for spark-ignition engines. In 2013, the Bioethanol Trade Association reported production growth of over 9 % at the nine production sites in Germany: that year, 672,000 tons of ethanol was manufactured, primarily from sugar beets and cereal grain.
Toward the goal of a new generation of biofuels, manufacturers will concentrate more on complete use of biomass. Ideally, the biomass employed will not compete with food production. Straw and wood chips will be used, and virtually no fruit. So-called biorefineries can transform regenerative raw materials, usually with the aid of biotechnical processes, into valuable products. In high-tech multi-function facilities, the material and energetic exploitation of biomass are interlinked as closely as possible. In order to set the course for biorefinery research and development, the BMEL, together with the BMBF, has commissioned experts to assess the potential of various concepts. Their Biorefineries Roadmap was presented in 2012. A biorefinery demonstration plant for biofuel manufacture has already been launched in Straubing, Germany. Moreover, a company at the Leuna industrial location is likewise aiming at biotechnological production of isobutene, a gaseous biofuel.
Attention is increasingly being directed to microalgae and cyanobacteria for biofuel production. These microorganisms offer the benefit that, with photosynthesis, they can use solar energy to produce energy-rich sugar molecules from carbon dioxide. Depending on their type and cultivation, these organisms store various concentrations of lipids, carbohydrates and proteins. Key technical problems must be solved, however, until the organisms can be used on industrial scale in the sense of the biorefinery concept: for example, the manner in which purification of the bio-based products can be improved.