What is biomass energy and how does it work?

Biomass energy is being used as a renewable power source with Drax Power Station in the UK an example of a power station converted from coal to renewable energy
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You probably do not need telling this, but the sun is pretty powerful. It heats Earth to a habitable temperature allowing life to flourish on our planet. It also releases chemical energy which is naturally absorbed and stored by every living thing. Welcome to the concept of biomass energy.

Organic material dead or alive contains this energy. Trees and plants, wood, crops, even human and animal waste including poo can be burned to release biomass energy.

Here, we will explain to you how the process works and try and answer the big question hanging over biomass – is it a renewable form of energy?

Types of biomass energy

When materials containing biomass are to be burned to release that energy, they become known as feedstock. This feedstock can be used to create three main types of energy: heat, electricity and biofuels.

As feedstock is burnt in biomass power plants, it creates heat which is your first type of energy. This heat can be used to turn water into steam, which then spins turbines to generate electricity. That is your second type of energy.

To increase the efficiency of biomass plants, many are Combined Heat and Power Plants (CHP) meaning that they produce both heat and electricity.

Biofuels are fuels made of biomass. They can come in solid, liquid or gas format and are used to generate power in the same way as petrol or diesel. The man who invented the diesel engine, Rudolf Diesel, actually came up with Biodiesel first when he manufactured an engine powered by vegetable oil.

An alcohol based biofuel called bioethanol was used in 19th century America to light lamps. We might think of biomass energy as a relatively new concept, but humans have actually been using organic material to generate power for centuries, long before fossil fuels came along to fire the Industrial Revolution.

Where is biomass energy used?

Biomass is becoming more commonplace across the world as nations look to reach net zero emissions. In the United Kingdom, both new biomass power stations are being constructed and existing fossil fuel facilities converted.

North Yorkshire’s Drax Power Station is set to be fully switched from coal to biomass by the end of 2021. Drax was the UK’s largest producer of carbon dioxide and part of the conversion works involves installing Bio-Energy with Carbon Capture and Storage technology which ensures no carbon is released during the burning of biomass.

The new Tees Biomass Plant meanwhile is the biggest biomass power station in the world. Located on the River Tees in the borough of Redcar and Cleveland, it cost £650 million to construct and will burn wood chips imported from North America and Europe to generate power for 600,000 homes.

Away from large-scale power generators feeding into the national grid, farms and agriculture and increasingly turning to biomass energy to fulfil their own power needs.

Animal waste and other agricultural materials can be turned into feedstock and burned in on-site farm biomass power plants. Not only is this biomass energy used to make a farm self-sufficient by supplying power and heat, but any excess energy can be sold to the national grid.

What are the positives of biomass energy?

There are plenty of positives in using biomass, especially when the feedstock is made up of waste products. Humans and animals are always going to create waste, which means there is no prospect of biomass running out as a fuel source anytime soon.

Because it is a naturally occurring material, there is little cost involved in extracting or producing biomass. Burning waste means less ending up in landfill whilst unlike some fossil fuels, it does not release any sulphur or mercury. It also releases less nitrogen than coal.

What are the negatives of biomass energy?

From what you have read so far, you could be forgiven for thinking that biomass is an all singing, all dancing form of renewable energy. There are however several negatives surrounding biomass energy which lead some to doubt whether it should even be classed as a renewable.

Most of these questions depend on the feedstock used. Burning waste that otherwise has no use is clearly a good thing. It is when feedstock is made up of crops specifically grown for biomass energy production or wood from deforestation that doubts begin to arise about the process.

If trees are cut down for use in biomass power generation, then more harm is caused to the environment than good.

Growing crops for biomass energy is a whole other can of worms. On a planet which struggles to feed itself, how can it be justifiable to give over vast swathes of growing space to crops for the sole purpose of burning them to create energy? The land, water and resources such crops use – only to then be destroyed – is a troubling aspect of biomass for a lot of people.

Is biomass a renewable source of energy?

In the eyes of the European Union and the United Nations, biomass is a renewable source of energy. Both have classified it as such, based on the grounds that you can quite literally renew anything you take from nature.

There will always be a plentiful supply of waste to burn and trees and crops can be replanted the instant they are cut down. This of course does not take into account that trees and crops take time to grow, which is one of the chief arguments against biomass being renewable.

A fully grown tree sucks much more carbon dioxide out of the atmosphere than a newly planted one. It can often take years for a replanted forest to reach the same capacity for air purification as the removed trees it is replacing.

Then there is the carbon which biomass energy produces. Organic material when burned releases all the carbon it absorbed during its life, so unless a power plant is equipped with a Bio-Energy with Carbon Capture and Storage system for preventing emissions like Drax Power Station, it is still contributing towards climate change.

Despite these questions, biomass remains a popular means of generating power. It supplies around 70 percent of the world’s renewable energy and 10 percent of energy use globally.

Africa and Asia in particular are benefiting from biomass, with decentralised power plants burning farm and agricultural waste to provide power to communities not connected to national infrastructure.

As a relatively cheap and easy way of bringing renewable energy to remote parts of the world, biomass has a huge role to play in powering the future.

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