Biomass – probably not the first word that springs to mind when the conversation turns to energy sources. And yet, it packs a bigger power punch than any other renewable energy source. In Germany, around 53 percent of renewable energy in 2018 was generated using biomass. The EU average was even as much as 60 percent.
At first glance this may come as a surprise, as renewables are often thought to only account for a portion of the electricity mix. Although wind, hydro and solar power do dominate when it comes to electricity generation, they contribute comparatively little when it comes to heating, with the exception of solar thermal energy, for example. Not to mention the fact that almost none of these energy sources can be used in the transport sector.
Biomass, on the other hand, can do it all, providing energy for electricity, heating and transport. Thus, the International Energy Agency IEA regards biomass as being the only renewable energy source which can be used to replace fossil fuels across all areas of application. In the long run, the IEA sees the green resource covering between a quarter and a third of the world’s energy demand.
Bioenergy comes in a variety of shapes and forms, proving just how versatile it truly is. On the one hand, there are plant-based products such as wood and pellets from timber shavings, along with rapeseed and soya oil, which are used as biodiesel, and other waste products from food production. In a broader sense, however, ethanol, i.e. alcohol, and biomethane, which are produced during biomass fermentation, also fall under this category.
Since time immemorial, wood has been the energy source of choice when trying to generate warmth or heat. The ‘discovery’ of fire is thought to be perhaps one of the most monumental developmental steps in the history of mankind, and for hundreds of thousands of years it remained the only form of energy used by humans in addition to manpower. Of course, the relevance of wood and charcoal as energy sources dwindled drastically in favour of fossil coal, oil and other energy sources – not least because the once abundant resource became scarce after the Middle Ages. Nevertheless, to this day in some parts of the world, wood remains the only option for heating and cooking.
The energy transition has put biomass back on the map as a sustainable energy source, which can help to meet climate targets. Biogas, which can be mixed with natural gas in the pipeline, helps improve the carbon footprint of many households when heating and cooking. Of course, it can also be used in an industrial setting, when thermal power plants are partly fed with biogenic waste or wood pellets from sustainable cultivation, for example.
In Germany, biomass supplied so much thermal energy in 2018 that it alone accounted for 40 percent of the entire country’s renewable energy. Across the EU, biomass supplied around three-quarters of all heating energy and globally in 2019, it accounted for almost two-thirds.
In thermal power stations, electricity and heat are generated simultaneously. Waste heat from electricity production is used as district or process heat. It is thus possible to use the energy contained in the fuel particularly efficiently.
This can be done on an industrial scale using biomass in the combustion chambers of thermal power plants. Biogas can also be used in smaller combined heat and power plants – for example in tenants’ sub-metered supply systems, which consume a variable proportion of biogas from the natural gas network, or in combination with biogas generation facilities. It is also possible to operate methane fuel cells with biogas.
Biogas is so popular that the UK and the Netherlands have been trading it since 2017. Incidentally, biogas is not to be mistaken with synthetically produced methane, which is produced using green electricity from hydrogen and carbon dioxide. Biogas, on the other hand, is generated during plant fermentation.
Power production from biomass takes place in biogas plant generators, for example, where waste heat cannot be used economically due to their location. Nowadays, thermal power plants are also ‘fed’ biomass. This is also RWE’s approach in the Netherlands: Forty percent of the fuels used at the Geertruidenberg power plant come from wood shavings, whilst Amer power station is to be converted to run on 80 percent biomass later this year. As a rapidly renewing resource, biomass is considered to be carbon neutral and will likely be used to help the Netherlands reach its climate targets.
In Germany, biomass is not exactly insignificant to power generation, either. In 2018, it contributed as much as 22.5 percent to the renewable electricity mix in Germany, roughly the same amount as photovoltaics. It accounted for around seven percent of total gross electricity generation, whilst the share of green electricity worldwide was as much as eight percent.
Nevertheless, biomass is integral to low-carbon power supply. This is because it is the only renewable energy source besides hydropower which makes a significant contribution to the base load. This means it is available on demand – i.e. no matter the weather or time of day.
Biomass could also contribute to load balancing in other ways: A start-up from Bavaria has developed redox flow batteries with an electrolyte made using biomass.
With the exception of green electricity and green hydrogen, which are used in electric and fuel cell cars, biomass is the only sustainable energy source which is currently being used in the transport sector. In the EU, it is mixed with petrol as ethanol: ten percent in E10 and around five percent in Super (E5).
Then there are also the vehicles which have been converted to use gas, which can also run on biogas. What is more, biogas can be liquefied to create LNG, which – similarly to biomethanol – is predominantly used in shipping. Various logistics firms and shipping companies are using this approach to reduce their greenhouse gas emissions.
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