How is bio-energy produced? This is a question that many people ask as bio-energy doesn't seem to have the same interest as other forms of renewable energy. Bio-energy is another type of renewable energy that can help reduce carbon emissions. In the same way as the history of wind energy, we have been producing bio-energy for centuries.
From the moment we found out how to burn wood, we have been using it as a form of fuel. So similarly, bioenergy production reduces greenhouse gases by replacing fossil fuels. As we improve technology to produce electricity from organic materials more cleanly, we will be able to adopt this renewable energy source more widely in place of fossil fuels6. So how is bio-energy produced, and what is it?
Bio-energy is carbon-neutral energy that we generate from agricultural residues and waste. In the past, this waste ended up in landfill, or we burnt it. However, when we burn it or allow it to ferment, it releases energy. The raw materials used for bio-energy include plants, wood waste, and other forms of waste. This raw material is typically called biomass.
Bio-energy also includes biofuel production3, which we can hope to use as a replacement for traditional transport fuels. So, from burning wood and waste to using oil, fats, and recycled grease, we can create bio-energy in the form of fuel and electricity.
So bio-energy creates energy from waste materials, but how is bio-energy produced? A bio-energy power plant can vary in size, ranging from a small heating system to a substantial industrial plant using thousands of tons of biomass fuel annually.
We can use several types of technology to release energy from biomass. These can range from combustion, a proven method, to newer technologies. The latest technologies can now turn biomass into liquid fuels that we can use instead of other more polluting oil-based liquid fuels.
So, we can create bio-energy by using the following processes:
Combustion is the most common process8. A biomass power plant will burn agricultural waste and other waste. Using heat, it converts the source into energy using combustion or gasification.
We can burn the waste to heat water before the steam spins turbines. This process uses excess air to create heat. The first part of the process involves the creation of vapors that can combust from biomass. These will then burn like flames.
The residual material, which is often charcoal, is then burnt, while a forced-air supply helps to create more heat. The gases then pass through a heat exchanger, producing steam, hot air, or hot water.
Biomass gives off gas naturally when it rots. When this occurs in the open, it releases methane, the primary component of natural gas, which can cause more harm than carbon dioxide. However, if we store the biomass in sealed tanks, they prevent the gases from entering the atmosphere. We can then extract it, allowing us to burn it. This leaves us with water and carbon dioxide, which is better for the environment.
Gasification is a thermal process whereby it converts plant matter into several gases that are combustible. These gases are hydrogen, carbon monoxide, methane, and ethylene. Using direct or indirect heating and a reduction in oxygen supply, the biomass creates gases that plants can burn.
This process involves burning biomass and waste food products at high temperatures with oxygen removed2. This causes new molecules to form. This changes the character of the waste and then ensures that a vast amount of energy is produced. This thermal decomposition of converting biomass creates products known as biochar, bio-oil, and a range of gases, including hydrogen, carbon monoxide, and carbon dioxide.
This uses an almost natural process. This process uses microorganisms to break down biomass. As a result, it produces methane and carbon dioxide gas.
The fermentation process breaks down the biomass anaerobically. A series of chemical reactions convert sugars into alcohol. We can then add yeast and bacteria before the ethanol goes through a distilling process, which increases the concentration of alcohol1. This then makes it possible to use in vehicles.
Bio-energy is a diverse and accessible form of energy. Homeowners can begin generating energy just by creating a compost heap. However, on a broader scale, large energy suppliers are now creating bio-energy power plants. They currently invest more money in bio-energy technology and research as they search for new sustainable energy sources.
The raw material is known as feedstock when we use biomass to create energy. These are specially grown or consist of waste products. There are dry feedstocks and wet feedstocks. Dry feedstock mainly consists of wood pellets that we then burn. This boils water and creates steam. They then use this steam to drive a turbine and generate electricity.
Wet feedstocks include food waste. These are stored in sealed tanks where they rot and produce methane. The gas can then be burnt to generate electricity.
Bio-energy is a source of energy that is extremely flexible. We have the ability to turn it up and down in order to meet demand. Therefore, it is a valid alternative to the likes of wind and solar energy.
As we know, biomass consists of waste or a special material that we can grow that is high in energy. However, there are many forms of biomass available for use.
Common forms of biomass are chips, bark, sawdust, and other forms of wood waste. This makes up the largest percentage of biomass energy. It is also mainly used for electricity generation.
We make this from vegetable oil, animal fat, and grease that we recycle. There is hope that biodiesel can replace the diesel we use in cars, trucks, and other modes of transport.
Solid waste is made up of waste biomass and non-biomass material. One tonne of solid waste has as much energy in the form of heat as 500 pounds of coal.
Bioethanol is a fuel that comes from plants that have been fermented to produce fuel. We now can use this in vehicles replacing traditional transportation fuels as technology evolves. In fact, even certain high-performance cars have the ability to use biomass fuels.
We can now use high-temperature digesters to quickly help sewage and agricultural waste rot. This then releases a gas we can capture and then use as fuel.
When we burn biomass, it does release carbon dioxide. However, the amount it emits is the same amount it absorbed when it grew. As a result, it does not break the carbon balance.
In contrast, when we burn fossil fuels, they release large amounts of carbon dioxide. This results in more carbon dioxide finding its way into the atmosphere. It is this process that causes global warming.
The energy efficiencies of bio-energy are better than that of other combusted sources. However, sustainability and environmental benefits can depend on our feedstocks.
There is some debate about the classification "carbon neutral," which makes bio-energy a renewable source worthy of scrutiny. When you consider that waste or crops are used to create biomass, it certainly provides a feasible alternative to how this waste would have been dealt with otherwise.
Of course, biomass or bio-energy is likely not entirely neutral, but what are we comparing it to? If we compare it to that of fossil fuels, then it is a far better option, even if it is not completely carbon neutral.
We are adopting a new and encouraging approach to bio-energy in the UK. There are several plants and biomass projects already up and running.
The Drax Power Station is presently the largest producer of polluting carbon dioxide in the UK. To address its environmental harm, It has been replacing coal burners with biomass and importing wood pellets from the United States and Canada. Using this method to convert biomass into energy has meant that 20 million tonnes of CO2 have been prevented from entering the atmosphere. Drax shows the way by demonstrating how big producers produce bio-energy.
Providing power for 78,000 homes is the Templeborough Biomass plant. While still a new plant, as it has only been open since 2017, it saves around 150,000 tonnes of carbon dioxide annually.
The Blackburn Meadows Cogeneration Plant uses heat from the combustion process. It then feeds this into local businesses using a direct heating system. In Kent, around 50,000 homes now benefit from bio-energy.
Finally, the largest biomass plant will soon be completed in the UK. The Tees Renewable Energy Plant will prevent 1.2 million tonnes of CO2 emissions from entering the atmosphere yearly. It will also have the ability to power 600,000 homes.
Bio-energy is also largely recognized as a renewable energy source in the US. In 2018, around five quadrillion British thermal units from biomass were used. This is a figure that is expected to grow. In 2016, the US produced 36.9 metric tons of bio-oil, a significant rise from the 3 million metric tons produced in 2000.
The top five performing states are North Dakota, Iowa, Mississippi, Georgia, and North Carolina.
The New Hope Power Partnership, based in Florida, is now one of the largest biomass power plants in the world. It has an installed capacity of 140MW, using sugar cane fiber and recycled urban wood. It now can provide electricity to 60,000 homes.
Throughout the rest of the world, bio-energy makes up 10% of the global energy supply. However, 70% of the electricity made from biomass comes from Europe and North America. This is down to the fact that we can use large, sustainable forests to supply wood pellets4.
Countries in Asia and Africa now use biomass energy. Across many developing countries, many communities do not have the ability to connect to a national power grid. Therefore, biomass plants are now providing partial electricity needs in these countries. In Brazil, a commitment has been made to move away from using fossil fuel-based oil. The aim is to replace it with liquid biofuels.
Bio-energy is a term that many of us have heard. However, many of us wonder, "how is bio-energy produced." Unlike wind energy or solar energy, it is slightly more reliant on human resources. This is especially the case when we consider the ongoing growth of crops or the sourcing of waste materials. Despite this, when we can use waste to create energy and even grow energy crops to burn, we have an element of control over the energy we produce.
Bioenergy does still produce greenhouse gas emissions. However, it presents significant CO2 reductions when compared to burning fossil fuels. In some ways, it is similar to fossil fuels in the way we use them to create energy.
Therefore, it seems as though it is a serious contender when it comes to a renewable energy source that will take its place as we strive to reduce our reliance on polluting fossil fuels.
|Inhibition of ethanol-producing yeast and bacteria by degradation products produced during pre-treatment of biomass. Klinke, H.B., Thomsen, A.B. & Ahring, B.K. Appl Microbiol Biotechnol (2004) 66: 10. https://doi.org/10.1007/s00253-004-1642-2|
|Patrick A. Horne, Paul T. Williams, Influence of temperature on the products from the flash pyrolysis of biomass, Fuel, Volume 75, Issue 9, 1996, Pages 1051-1059, ISSN 0016-2361, https://doi.org/10.1016/0016-2361(96)00081-6.|
|Biomass for Renewable Energy, Fuels, and Chemicals. By Donald L. Klass. Entech International Inc. 1998 Academic Press.|
|James A. Scott, William Ho, Prasanta K. Dey, Strategic sourcing in the UK bioenergy industry, International Journal of Production Economics, Volume 146, Issue 2, 2013, Pages 478-490, ISSN 0925-5273, https://doi.org/10.1016/j.ijpe.2013.01.027.|
|Biodiesel and Other Renewable Fuels Overview, U. S. Energy Information Administration / Monthly Energy Review June 2019|
|Günther Fischer, Leo Schrattenholzer, Global bioenergy potentials through 2050, Biomass and Bioenergy, Volume 20, Issue 3, 2001, Pages 151-159, ISSN 0961-9534, https://doi.org/10.1016/S0961-9534(00)00074-X.|
|Crops Grown For Bioenergy in the UK: 2017. Department for Environment Food & Rural Affairs (UK). 31st January 2019.|
|B.M Jenkins, L.L Baxter, T.R Miles, T.R Miles, Combustion properties of biomass, Fuel Processing Technology, Volume 54, Issues 1–3, 1998, Pages 17-46, ISSN 0378-3820, https://doi.org/10.1016/S0378-3820(97)00059-3.|