Our new energy report, Energy Independence 2025, identifies the options for increasing renewable energy generation within the Exeter region. We’ve already looked at how Solar, Wind and Hydro power is generated, in this Energy Explainers blog we will be introducing Bioenergy.

Put simply bioenergy is energy that’s created by burning waste plant and animal material. It is one of the oldest forms of energy production – going back to the invention of fire! This means it’s even older than solar power which is almost 200 years old.

Another name for plant and animal material that can be burned and turned into bioenergy is biomass. Plants and animals get their energy from the sun, energy that is stored and released when biomass is burnt.



Unlike fossil fuels which take hundreds of millions of years to form, biomass can be regrown and harvested over a much shorter period of time which makes it renewable. However, it’s important that it is harvested in a sustainable way to make it environmentally friendly.

Below are three of the most common types of biomass, the source of bioenergy, so grab a shovel and let’s dig in.

Waste wood

Wood is the most basic form of bio fuel – we burn it and it produces energy, whether we use it in the form of firewood or charcoal. Lots of scrap wood gets thrown away when trees are trimmed, so instead of throwing away all that waste it makes much more sense to use it as fuel instead of cutting down more trees.


Wood can be burnt more cleanly in wood-burning stoves, as they are 50% more efficient than a regular open fire. Although burning wood does produce carbon, if it’s burnt efficiently enough it still produces less pollution than heating homes with energy from fossil fuels like coal.

Food fuel

Biofuels have attracted a lot of attention as an alternative to petrol and diesel, some people have even modified their cars to run on used chip fat from pubs and restaurants. In France there’s a whole village that’s powered by biogas created from Sauerkraut juice!

Cleaner and more efficient forms of biofuel can be created from non-food crops such as special types of grass like miscanthus, also known as elephant grass, or farm waste – something which there’s plenty of in the Exeter region.

The two main types of biofuel are ethanol and biodiesel. Ethanol is produced in the same way as alcoholic drinks from grains and can be used to power any car that runs on gasoline. It can also be made from farm waste. Biodiesel is made by refining oil, fat, or grease that is collected from animals and can be used by any car that runs on diesel.

Closing the loop at Langage AD

Waste manure can be a really big problem for farmers, but the good news is there are new technologies which can reduce the emissions (and smells!) from large amounts of manure and capture biogas that can be turned into energy. Langage AD is a great example of this in Devon, turning cow manure and food waste into useful energy that’s used to make ice cream!


Langage AD has three tanks creating gas which is used to produce electrical power – it generates around five times the energy needed for Langage Farm to make its ice cream.

Each tank is fed with a range of waste materials. This could be anything from waste from the dairy farm that makes milk for Langage Ice Cream, to food waste from supermarkets and factories which is broken down and sterilised before entering the tanks.

Energy capture starts with a process called anaerobic digestion. Anaerobic digestion is where organic materials decompose in an environment without any air. The gases released during this decomposition, Methane and CO2, can then be captured and burned to produce heat and electricity.

For Langage Farm the biogas produced is trapped inside a giant balloon, which helps regulate the flow of gas, and then fed into a large engine which generates electricity.



The organic material spends an average of 60-90 days in the tank, and when it stops producing gas it can be used as fertiliser to grow grass for milk producing cows – closing the loop which started with the cows!

Although Biomass is definitely a renewable source of energy, some people question how environmentally friendly it is. If it can be produced from waste materials then it definitely does offer many benefits over fossil fuels, the big challenge is how to harvest it sustainably.


You can find out more about the Exeter Region’s bioenergy potential in Energy Independence 2025 which is available through our Insights page. It will provide a detailed analysis of how wind power can be generated in the region, in addition to other forms of renewable energy, and offer key recommendations for becoming energy independent.