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Eskom is in deep trouble. So much so that it is looking into alternative sources of energy to supplement the grid. One of these alternatives is biomass. When people think of renewable energy, using biomass as an alternative source of energy is not what immediately comes to mind. But what does it entail, and is it a viable option within the context of African energy independence?

What is the definition of “biomass”?

Biomass is plant or animal material used for energy production (electricity or heat), or in various industrial processes as the raw substance for a range of products. It can be purposely grown energy crops (e.g. miscanthus, switchgrass), wood or forest residues, waste from food crops (wheat straw, bagasse), horticulture (yard waste), food processing (corn cobs), animal farming (manure, rich in nitrogen and phosphorus), or human waste from sewage plants.

How does it work?

The first cave dweller to make and use fire inadvertently became the first human to harness biomass as an energy source. We still make use of this simple form of harnessing biomass to heat our homes and cook our food. Especially when having a braai in SA! The use of biomass generation has increased in transportation and electricity as this avoids carbon dioxide emissions from fossil fuel use. (The power generation Eskom currently uses)

But how do you get from biomass to electricity? All biomass is made of living things or things that were alive. This can include any plant or animal material, such as sugarcane or corn crops, wood chips, or even dung. Because these materials are organic, they contain energy, they’ve all absorbed chemical energy naturally from the sun.

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So let’s go through this step by step. Biomass energy is made possible by the sun. Energy is absorbed by the plants and trees through photosynthesis that is in turn released when organic matter is burned or decomposes. Let’s say you’ve collected plant waste from all the farms in your area. You would burn it to heat water, which is converted into steam. The pressure of the steam spins a turbine that powers a generator. And generator creates energy!

With animal waste, you would collect it in a large tank called a digestor that is filled with bacteria. The bacteria eat the waste and convert it into methane gas, and this gas is then captured. The methane gas is burned to heat water and produce steam. The rest of the process is exactly the same as with plant material. You can then say power to the poop that gives us power!

Pros 

  • Safe and economical.
  • A virtually inexhaustible source that can be stored for future use.
  • There are lots of waste generated every day that can be done away with, like landfills.
  • It can be produced locally.
  • It decreases dependence on fossil fuels, giving you energy independence
  • The burning of wood emits a substantial amount of CO2, but this can be offset by planting new crops, making biomass carbon neutral.

Cons

  • It produces enormous volumes of CO2. Wood emits more carbon than coal. This along with methane gas and nitrous oxide contributes toward global warming.
  • Biomass can produce ten times more energy than solar or wind, but it also produces the highest levels of harmful gasses.
  • This method can lead to deforestation and pollution if not controlled.
  • The process of extraction of biomass is expensive.
  • A biomass power plant requires a vast amount of space.
  • The recycling of waste requires a sizeable amount of water.

The use of biomass as a source of energy is as old as humankind but has some serious disadvantages to it that have to be considered. It’s a widely used process of generating energy and is especially important to third world countries to provide heat and to cook with. Using biomass should be carefully harnessed and balanced to ensure that we make use of it as cleanly as possible.

Thank you for reading this article. If you feel we have left out any important information or would like to contribute to this site and content, please get in touch with us by leaving a comment or emailing us.

Sources

The Department of Forestry, Fisheries and The Environment
The Conversation
Yokogowa
BioEnergy Consult
Energy Sage
International Institute for Environment and Development

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