Biomass: the key to decarbonisation? - The Renewable Energy Institute

Why Biomass?

While it does not always receive as much coverage as other forms of renewable energy, like solar and wind power, biomass is very widely used across the globe as a renewable energy source. In fact, biomass has been cited as a key factor in global commitments to reach net zero.

In 2021, biomass provided approximately 5% of total primary energy use in the United States.[1] In the UK, it is the second biggest source of renewable electricity.[2] And in the EU, it is the main source of renewable energy, accounting for 60% of the total produced. [3] Furthermore, the International Energy Agency (IEA) believes that bioenergy will make up 30% of all renewable energy production by 2023.[4]

From wood burners in private homes, to large scale industrial biomass power stations, this source of renewable energy will play an important role in the path to decarbonisation. However, it does require more action and thought than other forms of renewable energy, to ensure that the processes are in fact, renewable and sustainable. In the following article we will take a look at the process itself, the advantages and disadvantages, and its place in the future of the renewable energy sector.

What is Biomass?

Biomass refers to organic materials derived from plants and animals that can be burned to create energy. Some biomass sources, or feed stocks, include: wood, agricultural crops, animal waste and food waste. Chemical energy, derived originally from the sun, is present in all of the above and can be recaptured to create energy.

Different feed stocks can be converted into different types of fuels using various processes. Some of these include:

Combustion: wood or crops can be burned via direct combustion to create heat energy. This heat energy can also be turned into electrical energy, by using the heat to create steam which in turn powers an electrical generator.
Anaerobic digestion: animal waste can be converted to methane gas, using an anaerobic digestor and bacteria. In turn, the methane can be burned itself or converted to electricity. Food waste can also be broken down and turned into gas using a digestor. Fertiliser is also produced as a by-product in this process.
Fermentation: feed stocks can be fermented to create biofuels such as ethanol. During this process, glucose in plant matter is converted to ethanol using yeast.
Pyrolysis: feed stocks can be burned via pyrolysis (burning with reduced oxygen) to create a liquid biofuel or syngas (a synthetic gas made up of hydrogen and carbon monoxide).

As we can see, different types of biomass feed stocks work better for different processes. However, it is clear that there are many ways of capturing energy using biomass and also many advantages as well.

The Advantages of Using Biomass

Carbon Neutral

Small amounts of carbon are released during the processes above, however, when crops and trees are subsequently replanted, these then go on to absorb a similar amount of carbon dioxide, making the process carbon neutral. However, to ensure this, and for the process to be classed as renewable, the feed stocks needs to be taken from a sustainable source. Therefore it is important to ensure that wood for burning is taken from a reputably managed source, where replanting is guaranteed.

Reduces Waste

Not only does the process of burning food or animal waste create energy but it also reduces the amount of waste going to landfill. This also means a reduction in methane gas being released into the atmosphere, as the gas is collected safely before it can be released.

Reliable

Biomass does not rely on the weather like many other forms of renewable energy.
It is highly unlikely that we will ever run out of food waste or animal waste, whereas we can experience time periods in which wind levels or solar levels are lower than needed to create the energy required.

Disadvantages of Using Biomass

Sustainable Sourcing

As mentioned above, a great deal of care needs to be taken to ensure that biomass feed stocks are sourced sustainably. Sources such as grass or wheat are likely to be sustainable as they will be replanted. However, there can be questions over some sources, such as wood. If wood is burnt to create energy, but no trees are then replanted, the process becomes unsustainable and harmful to the environment.

Cost

Biomass can incur higher costs than other forms of renewable energy. Dedicated biomass energy plants are required, which takes up large amounts of land, as well as economic resources. Collecting, transporting and storing the feed stocks, not to mention the various types of technology that are required for the different processes, can make this option less cost effective than others, such as wind or solar power. Nevertheless, it will be interesting to see if advancing technology can help to minimise the impact of this particular disadvantage.

Biomass in the News

A recent study has suggested that rising temperatures may reduce the levels of potential biomass fuels available to us in the future.[5] The effects of climate change will mean lower crop yields, and in turn reduce the levels of biomass feedstocks available.

“There is a tipping point where climate change will severely impede our ability to mitigate against its worst effects. Biomass with carbon capture and storage including the manufacture of bio-based chemicals must be used now if we are to maximise its advantage.”
Professor James Clark, Department of Chemistry, University of York [6]

This would therefore suggest that efforts must be made to invest in Biomass now and maximise the benefits of this form of renewable energy, while we definitely can. In August 2022, the UK government launched a consultation on expanding biomass and associated carbon capture, awarding £37 million in government funding to this cause.[7] The aim of this investment is to make the process carbon negative and improve energy security amidst volatile gas markets.

As we have seen, there are often questions surrounding the sustainability of using wood as a feed stock. Now, three of the largest political groups in the European Parliament have backed the ending of subsidies targeted at wood burning.[8] In 2022, environmentalists also pushed for increased legislation on what can be labelled as sustainable biomass.[9]

However, there is also evidence of Biomass being used sustainably and responsibly to provide energy.

Successful implementation of Biomass Projects

In Sweden, ANDRITZ Group has created a new biomass boiler plant, in which recycled wood, bark, wood chips and sawdust are used to create heat energy.
This plant supplies more than 110 MW of heat to homes in the surrounding areas, the equivalent of 90% of homes in the Uppsala region of Sweden, and more than 180,000 people.[10] Furthermore, ANDRITZ have implemented specific technology, such as flue gas condensers, to increase efficiency and reduce emissions as much as possible. In Uppsala, this project forms a crucial part of their goal to become carbon neutral by 2030.

In the UK, the City of Edinburgh collects food waste from homes via communal food bins and this is processed just outside the city in a Biogen reprocessing plant. Through anaerobic digestion, 10,000 tonnes of food waste is converted to gas and fertiliser each year. In addition, it also creates a wide range of local jobs.[11]

Conclusion

Biomass may often be misunderstood as simply burning wood to provide heat. However, there is a wide range of technologies that we can use to gather energy from biomass. Alongside other sources, it is a crucial resource for us in the commitment to reach net zero targets.

While there are rightly questions over the use of burning wood to create energy, the use of food and animal waste as an energy source is a crucial avenue that must be explored further, in that it creates renewable energy and reduces waste at the same time. If technologies continue to be improved, and potential disadvantages are minimized, biomass can become even more significant in achieving our decarbonisation goals.

If you would like to find out more about Biomass you can study our accredited course, as part of the Sustainable Energy Consultant Expert Certificate or the overall Master in Renewable Energy Award.