The biomass sources of energy include:
- Wood and wood waste; e.g., firewood, pellets, lumber and sawdust.
- Crops and waste material, such as corn, plants and food processing residue.
- Biogenic materials found in waste, like paper, wool products and food waste.
- Animal manure and sewage.
The energy in biomass comes from the sun – plants will absorb energy from the sun and then convert carbon dioxide and water into nutrients. Technologies are then used to convert biomass sources into heat and electricity, in a similar way to that of fossil fuels.
Biomass energy sources can be burned to create heat, converted into electricity or processed into a biofuel.
Typically, energy generated from biomass is generated by direct combustion. Biomass can be burned directly to generate heat for buildings and water, for industrial process heat and for generating electricity using turbines. In this process, the biomass is burned in a boiler and produces high-pressure steam which then runs through a series of turbines. This movement causes the turbines to rotate which, in turn, drives a generator and produces energy.
The biomass materials are heated at high temperatures in closed, pressurised containers that are free from oxygen. The material then starts to break down and decompose to form a natural, renewable gas. This is then purified and used to produce electricity.
Biomass energy sources can also be converted into a liquid biofuel through the gasification process. During gasification, the biomass is exposed to high temperatures with controlled amounts of oxygen and/or steam within an enclosed environment. This process produces synthesis gas, or syngas, which is rich in carbon monoxide and hydrogen. Syngas can then be used as a fuel for diesel engines, for heating purposes and to generate electricity in gas turbines. The hydrogen can also be separated from the gas to be burned or used in fuel cells, while the syngas can be further processed to create liquid biofuels.
Biomass and biogas are both separate forms of carbon neutral biofuel, just in different forms. The main difference between biomass and biogas is that biomass is a solid material. Biogas is what it says on the tin: a gaseous compound created by anaerobic digestion.
Biogas is an environmentally friendly, renewable energy source that mostly consists of a combination of methane and carbon dioxide. It is created when organic matter is broken down by microorganisms in a process that is called anaerobic digestion – this is where the material is kept in an enclosed environment without oxygen.
Here are just a few of the biomass energy advantages and disadvantages:
- It’s always widely available as a renewable energy source as the materials used to produce biomass are endless.
- It’s carbon neutral, meaning it releases the same amount of carbon into the air as was once absorbed by the plants.
- It means people can rely less on fossil fuels, which are damaging to the environment in many ways.
- It’s less expensive than fossil fuels as the technology is much cheaper.
- Those that produce the waste material can use it as a source of revenue, using their own waste to be more profitable.
- Using waste to create biomass energy means that the material dumped on landfills is reduced significantly.
- It’s not as efficient as fossil fuels.
- It’s not completely clean, as using animal and human waste produces more methane.
- It may contribute to deforestation (in the future) as wood is one of the primary sources of biomass energy.
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