Organic matter is energy
When we think about renewable energy, the first concepts that come to our mind, is photovoltaic, wind or even hydraulic energy, but not bioenergy, even though it plays a fundamental role in the fight against climate change and energy transition. This renewable energy has increased its global installed power exponentially over the years.
Graph 1. Bioenergy capacity worldwide from 2009 to 2021 (in MW).
Bioenergy is the energy from the use of biomass: the biodegradable fraction of matter of organic origin, both vegetable and animal. This energy use can take three different paths: electricity, thermal, or biofuel generation. This April, our Blog is dedicated to this renewable energy source, focusing on biomass and biogas as an energy resource.
Biomass
Depending on their origin, different types of biomasses are distinguished: forestry, agricultural, livestock, industrial, and urban; through transformation processes (biological, mechanical, and thermochemical), producing bioproducts of economic, social, and environmental interest. Generically, biomass has as its objective the generation of thermal energy through boilers for heating, the production of sanitary hot water, and as a contribution to some industrial processes.
For example, in industries with drying operations, heat can be obtained from the combustion of residual biomass.
On the other hand, the generation of electricity from solid biomass occurs when the steam generated in the boiler passes to a steam turbine linked to an electric generator, where the kinetic energy of the turbine, is transformed into electricity.
Currently, to set biomass at the same stage as other renewable energies, it should not only increase its production capacity, but also gradually eliminate its traditional use. The following graph of 2020 shows a distribution of more than half of the global consumption coming from traditional cooking methods, and obtaining electricity, presents the shortest proportion.
Graph 2. Distribution of global bioenergy consumption in 2020
The first biomass installation in Spain, which functions as a heating and sanitary hot water central, was inaugurated in 1999 and was a pioneer project in Spain. This project, an IDEA initiative (Diversification and Energy Saving Institute), directly takes heat energy to the centres where it will be processed.
Over the years, this technology had a great boom; and that is tested, by the growth in the number of this type of installations. In 2005 there were only 9,556 biomass installations in Spain, and in a period of 10 years, these have grown to 160,036 plants generating a power of 12,570 GWh.
Graph 3. Annual domestic energy consumption from solid biomass in the European Union (EU-27) from 2000 to 2021.
The graph shows that energy consumption in Europe has increased progressively over the years, to a greater extent, because of the impulse given by the European Union and at the national level, as well as a promotion of using renewable energies.
Today the largest biomass plant in Spain is in Huelva and has a production capacity of 50 MW. This plant generates electricity from forestry, agricultural, and wood residues. Although if we compare it to our European neighbours, we find that the maximum power production plant in Europe is in the United Kingdom and has a capacity of 740 MW.
Graph 4. Country-by-country energy production from solid biomass in the European Union in 2021.
As we can see in the comparative graph of energy production from biomass at European level, Spain is situated on the 8th place with Germany being the main European producer, followed by France and Sweden.
Biogas
In addition to biomass, we also find biogas, combustible gas made from organic waste. The main sources are livestock and agro-industrial waste, sludge from EDARs (Urban Wastewater Treatment Plants) and FORSU waste (Organic Fraction of Solid Urban Waste).
Biogas is produced from anaerobic digestion, consisting of biological degradation by the action of micro-organisms in the absence of oxygen. It is mainly composed of methane (50-70%) and carbon dioxide (30-50%) and, if it is properly treated (segregation of carbon dioxide and moisture and impurities removal), produces a biomethane stream and can be injected into the national natural gas grid. This proccess in known as “upgrading”.
Biogas can generate thermal and electrical energy as well as biomass. In the case of thermal generation, this involves the direct use of biogas in boiler burners as a renewable alternative to natural gas. On the other hand, thermal energy Will be produced by units of cogeneration equipment with highly variable efficiency due to the diversity of their sizes (the larger the size, the higher the efficiency).
Methane was identified for the first time in the 17th century as a flammable gas from the bubbles generated in swamps. Although it was not until the 1980s that it gained some importance as a solution for energy recovery in agriculture and agro-industry (the first full-scale anaerobic digestor, built-in1859 in Bombay, India). Today, biogas is considered a renewable energy source, as an alternative to coal and oil and has contributed to sustainable economic development. The following graph shows the upward development of this energy worldwide.
Graph 5. Global biogas energy capacity from 2009 until 2021 (in MW).
Most of the world’s biogas production is focused in Europe with a total of 18.943 plants in 2019, producing 193 TWh. 725 of this biogas plants, are producing biomethane.
Graph 6. Global biogas production in 2019 by region (in billion cubic metres).
Unlike the rest of Europe, Spain has shown a moderate development of this technology, with 130 to 146 plants reporting biogas consuption in 2020. The estimated production of these plants is around 2.74 TW. Concerning biomethane production, Spain has five plants where biogas purification is carried out (1).
Bioenergy nowadays is growing faster and faster as it is the key to the current management challenge caused by the exponential increase in organic waste, and unlike other renewable energies, it shows an independence that allows continuous energy generation.
1. EBA, European Biogas Association. ANNUAL REPORT 2020. [Online] https://www.europeanbiogas.eu/wp-content/uploads/2021/01/Annual-Report-2020-new.pdf.