In a world struggling with the climate emergency, biomass appears as an alternative renewable energy source to fossil fuels. Discover the sources, advantages, and disadvantages of biomass, and also the lack of consensus it has generated.
A study by researchers at the Weizmann Institute of Science has shown that by 2020 the mass of man-made materials - from buildings to buttons - the so-called anthropogenic mass, has already exceeded the planet's total biomass.
On average, according to another study published in Nature, for every person in the world, more anthropogenic mass than their body weight is produced each week. But what is biomass anyway?
What is biomass?
Biomass is biodegradable organic matter of biological, plant, or animal origin that can be converted into green fuel or biogas. It can also consist of biodegradable waste material from municipal waste as well as sewage and sludge from water treatment plants.
Examples of biomass used for energy production
- Agricultural residues: such as cereal straw, rice husks, crop residues, and sugarcane bagasse;
- Forest residues: branches, leaves, and other wood residues from activities such as tree thinning and the timber industry;
- Plants grown specifically for biomass production, such as sugarcane, corn, sorghum, elephant grass, and energy willow
- Food waste, such as fruit and vegetable peelings, food scraps, and waste resulting from food processing;
- Wood waste: chips and waste from the woodworking and carpentry industry;
- Manure and waste from livestock, such as cattle, pigs, and poultry;
- Municipal solid waste, such as tree trimming waste, yard waste, food waste, and paper waste.
Biomass can be directly burned to generate heat or electricity, or converted into oil or gas to produce solid, liquid and gaseous biofuels, which can be used in various sectors, including transportation (one of the most polluting sectors in the world). The energy resulting from the conversion of organic matter is called bioenergy, a renewable energy resource that currently, according to the Directorate General of Energy and Geology, represents approximately 11% of global primary energy consumption.
Biomass remains particularly important in many developing countries, especially for cooking and heating. However, the use of biofuels in transport and for electricity generation is also increasing in many developed countries, as a consequence of measures to reduce CO2 emissions from the use of fossil fuels.
Advantages and disadvantages of biomass use
The scientific literature contains widely diverging opinions about the advantages and disadvantages of biomass use. Concerns are mainly expressed about the climatic effects of using forest bioenergy, while emphasizing the need to ensure sustainable forest management.
Determining whether a forest system is sustainably managed requires consideration of a wide range of factors that together determine biodiversity, productivity, regeneration capacity, vitality, and the ability to fulfill ecological, economic, and social functions.
Confronting various sources, it is easy to see that what is often pointed out, by some, as an advantage, will appear, by others, as a disadvantage.
Some of the advantages identified
- In contrast to coal- and gas-fired power plants, power plants using biomass do not contribute to increased levels of greenhouse gases (GHGs). The level of CO2 generated in the combustion process of biofuels is no greater than the amount of CO2 produced during the natural transformation process of plants (photosynthesis).
- Biomass is a clean, renewable energy source. The main energy comes from the sun, and biomass that results from plants or algae can grow again in a relatively short period. Trees, crops and solid waste are always available and can be managed sustainably.
- If crops are maintained sustainably, they can help offset carbon emissions by absorbing carbon dioxide. Many feedstocks can be harvested on marginal land or pasture, where they do not compete with food crops.
Some of the disadvantages identified
- High electricity and heat consumption appears as one of the arguments against biomass-fired power plants. The production process itself is time-consuming and requires the use of expensive technology and equipment, which creates significant costs and a burden on the environment.
- Biomass is a raw material with a lower calorific value than coal or natural gas. About 50% of biomass is composed of water, which is lost in the energy conversion process. Some scientists and engineers estimate that it is not economically feasible to transport biomass more than 100 miles from where it is processed.
- Burning biomass releases carbon monoxide, carbon dioxide, nitrogen oxides, and other pollutants and particulates. If these pollutants are not captured and recycled, burning biomass can exceed the amount of pollutants released by fossil fuels.
- As a result of burning biomass in boilers, large amounts of ash are also generated, which requires frequent removal and cleaning of heating facilities.
- Pellets, chips and straw (biomass sources) require proper storage. If not properly conditioned, they quickly absorb moisture and their efficiency degrades.
- If some of the biomass sources are not replenished as quickly as they are used, they can become non-renewable. For example, a forest can take hundreds of years to re-establish itself.
According to Columbia Climate School, as discussions and discoveries around biomass continue to evolve, state, federal, and international regulations need to make a clear distinction between the types of biomass energy that are beneficial and those that are harmful.
Considering all biomass, regardless of its source, as carbon neutral could lead to an increase in greenhouse gas emissions globally, as well as increase the risk of large-scale deforestation of the world's largest forests.