What is landfill gas?

Landfill is a type of biomass; biological material used as a renewable energy source. It usually comes from waste plant and animal matter. When they decompose, they produce a mixture of methane and carbon dioxide, both greenhouse gases. This mixture is known as ‘landfill gas’.

These green house gases escape into the atmosphere if not collected. Landfill gas is a valuable resource and can be extracted. It can be used as a clean and safe energy source to produce electricity or heat.

How environmentally damaging is methane?

Methane, an odourless and colourless gas, is lighter than air and is 21 times stronger than carbon dioxide. Carbon dioxide is known as the greatest contributor to climate change, and methane is only second to carbon dioxide. Methane can create explosions if there is 5-15% of it in the air; it can also become flammable if the percentage increases from 15%.

When there is too much methane in the air, there is not enough oxygen, causing a problem for people because they can't breathe. 

What are its environmental impacts?

A large number of environmental impacts may occur due to the landfill operations. There can be accidents where scavengers get buried under waste piles, pollution, release of methane and carbon dioxide, and harbouring of diseases by rats or flies.

As landfill sites must be licensed by Environmental Protection Agency (EPA), they won't cause pollution if operated correctly. Special training is required for the correct operation and management of these sites. 

Where can landfill sites be located or developed?

Landfill sites can be located where local authorities and industries take their waste to be buried and compacted with others. They are also permitted to be located at remote sites, with the use of 'rail-haul' permits.

There are quite a few landfill sites in Melbourne, and a nine are currently developing. There is a total  of 133 plants currently operating in Australia and there are 25 in Melbourne alone. 

How sustainable is it?

Landfill gas is sustainable as long as it is extracted at a reasonably consistent flow and quality, so as to not decrease the landfill available. This is achieved by the process used to extract landfill gas. 

How is landfill gas extracted?

Landfill gases are extracted at gas extraction and power generation facilities. A blower is used to extract the gas from the landfill sites into the extraction system. It goes through an set of wells interconnected by a network of buried pipes. The landfill gas is extracted and combusted to generate electricity. 

What are the advantages & disadvantages of landfill power?

'Green' energy source	Advantages	Disadvantages
Landfill Gas	•         Needed to reduce methane gas emissions •         Efficient use of waste products •         Positive extraction prevents soil infiltration, preserves vegetation •         Clean, visually and audibly unobtrusive sites •         Makes electricity, heat and fuels •         People willing to pay for 'green energy' (e.g. organic food)	•         Recycling reduces landfill available •         Generation site must relocate when gas is exhausted •         Much larger volumes of landfill are required for the same amount of electricity produced by fossil fuels