Generating Electricity: Biomass

Biomass in Canada

2 percent of Canada’s electricity comes from biomass. Biomass is the third largest renewable source of electricity in Canada. The electricity generated from biomass increased 54% from 2005 to 2015. Most biomass plants are in British Columbia, Ontario, Quebec, Alberta, and New Brunswick.

Did you know?

Canada is the world’s second-largest exporter of wood pellets. Wood pellets are a type of biomass. Wood pellets are made of sawdust and other industrial waste.

What is biomass?

Biomass is organic material that comes from recently dead plants and animals. Biomass contains energy that once came from the Sun. Plants convert energy from the Sun into chemical energy. This process is called photosynthesis. Animals that eat plants use and store this energy in their own bodies. Fossil fuels are not considered as biomass.

Wood, waste from crops, landfill gas, and municipal solid waste are some of the common types of biomass. In Canada, industrial wood waste is the most common type of biomass.

How do we use biomass to generate electricity?

There are three ways of using biomass to generate electricity. Biomass is either:

1. burned;
2. broken down by bacteria;
3. or converted to a gas or liquid fuel.

Burning biomass is the most used method. This is also called combustion. It is like burning fossil fuels. The term for burning matter to generate electricity is thermal generation.

Electricity isn’t produced directly from this combustion. Burning solid biomass materials heats giant boilers filled with water. This transforms liquid water into steam. The steam creates pressure in the boiler. The force of the steam rotates a turbine. The turbine then moves a wire coil in a generator.

Some biomass plants generate electricity by burning methane. Methane is a gas that can be collected from landfills. These plants use a slightly different process than plants that burn solid biomass. The products of burning methane, instead of steam, cause the turbine to spin. As with solid biomass, the rotation of the turbine drives a generator. 

Generators are devices that generate electricity. Generators convert mechanical energy into electrical energy. First a force from the water vapour or gas makes the rotor turn. The rotor has a coil of wire that spins inside a fixed magnet around it, called the stator. The rotation creates a magnetic field which forces electrons to move along the wire. This generates electric current. We call this electromagnetic induction. The metal wire constantly moves inside the magnet. This creates a continuous flow of electrons, generating electricity.

Did you know?

Fuels made from biomass can run engines or heat homes.

How much power can biomass generate?

Biomass facilities can generate anywhere from 2 to 1000 megawatts of electricity. At the end of 2014, Canada had 70 biomass power plants. Together, these plants can produce 2 043 megawatts of electricity. Industries, such as pulp and paper plants, use about two-thirds of this electricity.

Atikokan Generating Station is North America’s largest 100% biomass power station. It is located in Northwestern Ontario. This station used to generate power by burning coal. After modifications in 2014, it now burns wood pellets. It can generate 205 megawatts of electricity by burning wood pellets. This is enough electricity to power about 70 000 homes.

Advantages of Biomass Electricity Generation

Unlike other types of renewable energy resources, biomass plants can generate power all the time. They don’t rely on intermittent things such as wind or sun. This makes electricity from biomass reliable.

But biomass is different from other types of renewable energy sources. Unlike the wind and the sun, biomass is consumed when electricity is generated. To make biomass renewable, the consumed plant material needs to be replaced as quickly as it is used. This may be through growing new crops or planting trees. If this were to happen, then burning biomass would not increase greenhouse gas levels. But if it does not, then burning biomass would increase greenhouse gas levels.

Another advantage of using biomass is that it can prevent some types of waste from going to landfills. 

Disadvantages of Biomass Electricity Generation

Burning biomass produces similar greenhouse gases to burning fossil fuels. These greenhouse gases contribute to rising global temperatures. Burning biomass also releases other pollutants into the air. These pollutants include particulate matter, nitrogen oxides, sulfur and dioxide. Air pollution can cause respiratory issues, heart disease, cancer, and other health issues.

Biomass-generated electricity can also impact the environment in other ways. For example, cutting down trees can lead to deforestation. Growing plants to use as biomass can impact soil quality and water usage. These plants take up space where wild plants could have grown.

We could solve some of these problems with technology. For example, more careful land-use, filters or cleaner sources of biomass could help. Other sources of biomass, like methane gas from food waste, may be more common in the future. These technologies may make producing electricity from biomass better for the environment.