Biomass is a special source of renewable energy in a number of ways. First, it can directly provide all three types of energy carriers: electricity, heat, and fuel (liquids, solids, and gas). Second, it is easily storable and dispatchable; when there is not enough sun or wind, biomass-fired generators can be ramped up as need be. Third, the major drawback: biomass requires strict management to be sustainable. No matter how many solar panels we install, we will not use up the sun any faster, nor will we measurably reduce the amount of wind on Earth if we keep installing wind turbines. But with biomass, we have to avoid resource depletion, prevent monocultures from reducing biodiversity, and ensure that the energy needs of rich countries are not met at the expense of food needs in poor countries.
Because it can cover such a wide range of energy services, biomass makes up a far greater share of the world's energy supply than hydropower or nuclear (which only provide electricity) – indeed, more than all other renewable energy sources combined. According to Ren21, biomass covered more than 14 percent global final energy demand in 2014 (most of which was traditional biomass), whereas the share of nuclear power has fallen to 2.5 percent.
Biomass in Germany
Nowadays, when we talk about biomass, we increasingly mean ethanol from corn, biodiesel from rapeseed, biogas from organic waste and corn, wood pellets made from sawdust, etc. – as opposed to firewood, dung, etc.
Bioenergy generally comes from two sources: forestry and agriculture. Within the EU, Germany is the greatest producer of wood, and wood is by far the greatest source of bioenergy in the country. Roughly 40 percent of German timber production is used as a source of energy, with the rest being used as material. Germany is also the leading biogas market – beginning in 2015, almost two-thirds of Europe's biogas plants were installed in Germany.
In 2016, Germany already used nearly 2.7 million hectares of its arable land for energy crops. This area is equivalent to 16 percent of the 16.7 million hectares of agricultural land in Germany. The upper limit for bioenergy is 4 million hectares by 2020. Studies show that the share of bioenergy can be increased within these limits as a result of the decrease in population in the next few decades and increasing hectare yields in the agricultural sector. The German population is expected to shrink from just over 80 million in 2016 to below 70 million in 2050. Environmental organizations, however, point out the environmental impacts of energy crops. For example, the large increase in the cultivation of corn for use in energy production (and the problems associated with corn monocultures) is frequently associated with the plowing of valuable grassland. Energy crops can also have adverse effects on the quality of groundwater and cause soil erosion. To prevent these effects, Germany’s Renewable Energy Act (EEG) - the main law behind the Energiewende - limits the amount of corn and grain eligible for special compensation. In addition, a set of incentives seeks to encourage increased use of less environmentally polluting substrates, such as material from landscape management activities and residues.
Renewable energy made up around 13.5 percent of total final energy consumption in 2016. Nearly 37 percent of that was biomass in the heat sector, along with over 10 percent biofuels and eight percent biogas in the power sector. In total, bioenergy made up 57 percent of total renewable energy supply in Germany in 2015, equivalent to 7 percent of primary energy consumption.
The potential of sustainable domestic bioenergy in Germany would therefore seem to be limited to around ten percent of overall energy supply – at least at current levels of consumption – but Germany could increase those shares by reducing consumption.
Today, Germany uses biomass mainly of domestic origin. The challenge will be to increase biomass usage for energy without drastically increasing imports. Germans are already concerned about the clearing of rainforest for palm oil plantations and about conflicts with food production in developing countries. As the German Environmental Ministry has stated, "the expansion of biomass production for energy use [must not conflict] with food security, the right to food, and the protection of the environment and nature." Therefore, along with the European Renewable Energy Directive, biofuels and other liquid bioenergy carriers must satisfy strong sustainability criteria to count towards the targets for quotas and be eligible for the bonuses set forth in the Biomass Sustainability Ordinance. It remains unclear, however, whether strict criteria are sufficient to prevent the use of biomass for energy from increasing food prices around the world.
For the future, the use of biomass seems particularly important in three areas: as fuel for air transportation and heavy-duty vehicles (where electric mobility or other technical alternatives are not readily available), for industrial process heat, where high temperatures are required, and for cogeneration, because cogeneration plants convert biomass to electricity and heat with the highest efficiency and greenhouse gas benefits.
In addition, biogas and hydrogen in particular are seen in Germany as a crucial way of storing energy seasonally to provide sufficient electricity on the dark evenings of winter, when power consumption is the highest in Germany and no solar power is available. Nevertheless, the German government imposed a limit of 100 MW of new biogas units per year in August 2014, partly because of concern about environmental impacts, but primarily in order to rein in costs. In the amendments adopted to the law in 2017, the 100 MW limit was roughly retained. In the future auctions, between 150 and 200 MW of biomass power plants will be tendered.