burning trees to save the world?
what’s in it for you?
• understand what biomass is, where it comes from and how we utilize it
• learn how European politics shaped the global biomass industry
• build the foundation to critically evaluate the potential of biomass for your community9-12 minute read
Burning wood gave us our first taste of external energy and kickstarted civilization as we know it today. Supplanted by the rise of fossil fuels over the last 200 years, timber faded more and more into the background. Nowadays, however, with the promise of saving the world as a carbon-neutral energy source, biomass energy is staging a major comeback. Proponents tout it as a green saviour, critics argue it is a false hero. In a world of increasing carbon emissions, burning more wood can only be expected to further contribute to growing air pollution and deforestation. Adversaries meanwhile advertise biomass as a local, net-zero energy source with rural job creation potential that can utilize untapped residual waste. But which path should we take?
We stand at a crossroads: controversies surrounding biomass power demand our urgent attention and a long-term perspective as the choices we make today will directly affect our lives and that of our children. Within this article we will equip you with the seed and saplings to understand the ongoing debate. Let's strip the alleged hero of its concealing cape and examine whether the renewed enthusiasm for biomass incineration is justified!
a short biomass refresher.
Biomass, a pretty old term coined by German biologist Reinhard Demoll in 1927 [1], describes the organic mass of living plants, animals, fungi, and bacteria within a given volume and can be categorized according to its origin, namely aquatic, animal, human waste or wood biomass [2].
While the underlying chemical reactions that generate the stored energy within biomass differ depending on the category, biomass derived from our trees and bushes utilizes a process we know as photosynthesis. Starting from the bigger picture, plants offer several services to us Earthlings, including the creation of microclimates and niche habitats for animals [3, 4]. At the same time, plant ecosystems also act as elements of larger systems, influencing global nitrogen cycles by serving as biochemical reservoirs and contributing to weather formation [5, 6]. Within photosynthesis, plants use solar energy and water supply to convert carbon dioxide into storable carbohydrates with a high energy content - typically wood. As a side effect, they also emit vital oxygen for us. This conversion of solar energy into chemical energy renders the sun's energy accessible to plants themselves as well as to herbivores, thereby forming the energetic backbone of diverse wildlife we see today. Burning plant materials releases the stored energy and forms the fundamental process of biomass power that keeps our homes warm in winter [7].
from logging to incineration.
Let's pretend you are the operator of a biomass power plant, seeking to obtain biomass for incineration to power your neighbourhood and earn your living. Where should you look for your input materials? Thanks to modern transportation networks and global markets, possibilities are nearly endless, yet forests are the common denominator.
Globally, tropical natural forests such as those found in Latin America, Africa, and parts of Asia are particularly attractive due to their dense vegetation and hence high biomass contents, frequently resulting in illegal logging and widespread deforestation, an issue we will discuss in more detail in the second article of this series. Aside from natural forests with little to no human influence, the old-established timber industry created forest plantations whose trees are cultivated primarily for subsequent lumber use in industry and energy applications [8]. Determined by climatic and soil constraints, plantation developers have to choose suitable tree species - as money matters, fast-growing trees with high fertility, adequate timber quality, and resistance to pests as well as severe weather events are naturally preferred [9, 10], resulting in the domination of water-gobbling Eucalyptus and low-maintenance conifer trees across artificial forests world-wide.
After successfully harvesting a forest, either by clear-cutting or selected cutting, the collected trees are then sent to a sawmill or stored for later use (Step 2 in Fig 1, below). To prevent quality deterioration during storage, the logged stems get to enjoy regular baths in local ponds or less luxurious showers.
In the case of biomass power as intended final use, the trunks and branches (primary raw materials) and sawdust or bark residuals from previous operation (secondary raw materials) are shredded and pressed into wood pellets or wood chips at designated pellet factories before being either trucked or shipped to biomass energy facilities (Step 3 and 4 in Fig 1, below).
Fig 1. Click to enlarge. The lifcycle of woody biomass can be broken down into five broad steps, starting from tree growth and logging to the final incineration
Once available at the biomass power plant (Step 5), the combustible wood pieces are brought to boilers via conveyor belts and incinerated at high temperatures. The heat from the combustion unlocks the energy stored with the wood and is utilised to heat up so-called feedwater. Ultimately, the feedwater turns gaseous and is harnessed to power a turbine. The moving steam turbine is connected to a generator and converts the kinetic energy of the rotation into electricity. The hot steam that previously drove the turbine can then either function as district heating for households or serve as renewed feedwater in the boiler again after being cooled (in "closed water systems"). In modern plants, the combustion gases produced in the boiler are purified after their "exploitation" and ultimately discharged via a chimney. Both the electricity as well as the generated heat are ultimately sold to neighbouring industrial and utility companies [11].
Fig 2. Click to enlarge. Biomass can generate both electricity and heat for industrial and residential customers. Visualization obtained from Renewables Energies Agency [12]
the renewed ascent of biomass energy.
Until the 17th century, wood comprised the main source of energy, utilised together with plant oils and charcoal for baking, heating, and construction. With the discovery of coal, the industrial revolution eventually began in England during the 18th century. Driven by the high cost of crude oil during the OPEC crisis in the 1970s, bioenergy including biomass incineration experienced a renaissance as researchers and policy makers investigated alternative energy sources, promoting biofuel as a possible energy carrier at that time. Yet, the real breakthrough did not occur globally until the end of the 2000s.
Growing dependency on energy (imports) and spreading climate change conscientiousness convinced the European Commission for far-reaching change. Determined to become a low-energy economy with secure, locally generated and sustainable power access, the continent moved towards energy market liberalisation and integration.
Ultimately, in early 2009 the Renewable Energy Directive (RED-1, 2009/28/EC) was published, formally binding the EU to achieving a 20% share of renewable energy in its gross final energy consumption by 2020. Surprisingly, aside from wind and solar, (wood) biomass energy also made it onto the list of renewable energy sources. The consequence - the classification of biomass as a clean energy source “suddenly created a market for low-quality wood” (secondary raw materials) as Elbein [13] elegantly describes.
Market participants reacted rapidly. Enviva and Drax, leading American and British pellet producers, commenced their first mills in 2011 and 2013 respectively, ushering in the return to biomass energy globally. The jump-start of biomass energy received further tailwinds with the collapse of the local European solar panel industry. Over the following years, biomass took off in the European community, nearly doubling its share of the EU's gross final energy consumption from 5.9% in 2005 to around 10.3% in 2017, while also tripling its installed electricity generation capacity to 32 GW during the same timeframe.
Overall, biomass energy has been dominating European greening efforts ever since. Using between 37 to 51% woody biomass as inputs, it has been the continuously dominating source for total renewable energy at around 41% in 2021. While wind and more recently solar technology deliver the lion’s share of renewable electricity in Europe, bioenergy is what brings Europeans joy during cold winters.
Fig 3. Click to enlarge. Historical use of renewable energy sources for heating and cooling in the European Union from 2005 to 2020 , obtained from the European Environment Agency [14]
The EU's ongoing strategy to utilise biomass to achieve climate targets as well as the growing adoption from other countries, drives projections of consumption even higher. In their “Fit for 55” strategy publication, the EU Commission members outline future scenarios. Depending on the adoption of electric transportation and energy saving trajectories, bioenergy (including adjacent biogas and bioliquids) is expected to extend its current position within the energy system. With the goal of decarbonizing heavy industry, across most scenarios, an increase of more than 60% biomass is expected or rather desired.
Globally, the World Energy Council assumes an eightfold increase in energy generation from biomass by 2050, considering a coverage of 30% of total energy needs with biomass alone as a realistic case [15]. What an amazing “growth” story! The EU commission definitely pulled a big rabbit out of its hat, right!?
While the EU commission and biomass proponents are advocating the combustion of forest biomass as a carbon neutral renewable energy source and are emphasising sourcing from sustainable resources and bio waste (secondary raw materials), conservation-oriented NGOs like Partnership for Policy Integrity and several hundred scientists decry potential shortcomings within both the sourcing concept and the overall system [16]. Despite the formal establishment of restrictive import regulations and allegedly strict local sourcing requirements, investigative journalists uncovered mafia-style clear-cutting both abroad as well as in eastern European forests. The accusations of adversaries range from incentivizing deforestation to complete rejection of the advertised carbon neutrality, alluding to purported carbon accounting wizardry among others. Yet, unphased proponents brush off criticism using credible peer-reviewed academic literature.
Lines seem to be drawn in the sand and the interdisciplinary nature of the topic, bordering ecology, forestry, energy science, and economics allows for a myriad of perspectives. In our next article we will provide you with an overview of relevant biomass power considerations, ranging from environmental and health threats to employment opportunities, while also introducing you to a holistic framework that allows you to critically evaluate the risks and rewards of biomass energy.
our two cents:
The decision of the EU Commission effectively revived biomass as an energy source. Today, biomass is a hotly contested area with diverging opinions and, so far, contradictory research results without a simple answer. Do you think biomass would have become so dominant worldwide without the EU? We are not convinced yet. While we see mostly risks and less opportunities considering global nature conservation problems, we will present you a structured analysis with our final verdict in the second part.-
[1] Demoll, R. "Betrachtungen über Produktionsberechnungen." Arch. Hydrobiol 18, no. 3 (1927): 460-463.
[2] Vassilev, Stanislav V., David Baxter, Lars K. Andersen, Christina G. Vassileva, and Trevor J. Morgan. "An overview of the organic and inorganic phase composition of biomass." Fuel 94 (2012): 1-33.
[3] Chen, Jiquan, Sari C. Saunders, Thomas R. Crow, Robert J. Naiman, Kimberley D. Brosofske, Glenn D. Mroz, Brian L. Brookshire, and Jerry F. Franklin. "Microclimate in forest ecosystem and landscape ecology: variations in local climate can be used to monitor and compare the effects of different management regimes." BioScience 49, no. 4 (1999): 288-297.
[4] Silvertown, Jonathan. "Plant coexistence and the niche." Trends in Ecology & evolution 19, no. 11 (2004): 605-611.
[5] Makarieva, Anastassia M., and Victor G. Gorshkov. "The Biotic Pump: Condensation, atmospheric dynamics and climate." International Journal of Water 5, no. 4 (2010): 365-385.
[6] Mylona, Panagiota, Katharina Pawlowski, and Ton Bisseling. "Symbiotic nitrogen fixation." The Plant Cell 7, no. 7 (1995): 869.
[7] McKendry, Peter. "Energy production from biomass (part 1): overview of biomass." Bioresource technology 83, no. 1 (2002): 37-46.
[8] Verwijst, Theo, Anneli Lundkvist, Stina Edelfeldt, and Johannes Albertsson. "Development of sustainable willow short rotation forestry in northern Europe." Biomass now-sustainable growth and use (2013): 634.
[9] Hinchee, Maud, William Rottmann, Lauren Mullinax, Chunsheng Zhang, Shujun Chang, Michael Cunningham, Les Pearson, and Narender Nehra. "Short-rotation woody crops for bioenergy and biofuels applications." Biofuels: global impact on renewable energy, production agriculture, and technological advancements (2011): 139-156.
[10] McKendry, Peter. "Energy production from biomass (part 1): overview of biomass." Bioresource technology 83, no. 1 (2002): 37-46.
[11] EDF. “Biomass, a Renewable Energy Source That Generates a Low Level of CO2.” EDF FR, February 22, 2022. https://www.edf.fr/en/the-edf-group/producing-a-climate-friendly-energy/doubling-the-share-of-renewable-energies-by-2030/biomass-a-renewable-energy-source-that-generates-a-low-level-of-co2.
[12] Renewable Energy Agency. “Biomass Combined Heat and Power Station.” Deutschlands Informationsportal zur Energiewende - Agentur für Erneuerbare Energien. Accessed July 24, 2023. https://www.unendlich-viel-energie.de/media-library/charts-and-data/biomasss-combined-heat-and-power-station.
[13] Elbein, Saul. "Europe’s renewable energy policy is built on burning American trees." Vox, March 4 (2019).
[14] EEA. “Historic Use of Renewable Sources in EU Heating and Cooling (2005-2020) and 2020 Nreap Levels.” European Environment Agency, June 14, 2023. https://www.eea.europa.eu/data-and-maps/figures/historic-use-of-renewable-sources.
[15] Frei, Christoph, Rob Whitney, Hans-Wilhelm Schiffer, Karl Rose, Dan A. Rieser, Ayed Al-Qahtani, Philip Thomas et al. World energy scenarios: Composing energy futures to 2050. No. INIS-FR--14-0059. Conseil Francais de l'energie, 2013.
[16] Grunwald, Michael. “The ‘green Energy’ That Might Be Ruining the Planet.” POLITICO, March 26, 2021. https://www.politico.com/news/magazine/2021/03/26/biomass-carbon-climate-politics-477620.
