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Fast five on anaerobic digestion

Thursday, 20 September, 2018

As the LGAQ and the Queensland State Government continue to work together towards a zero waste to landfill future, the solutions that will be a part of that future are taking shape. One of the solutions that is emerging as a front runner, according to the Peak Services Viability assessment, is anaerobic digestion.

Here’s a quick rundown to get you up to speed: 

1.What is anaerobic digestion? 

Anaerobic digestion is a process whereby microorganisms are used to destroy biodegradable content. It is used both domestically and commercially to tap the release of energy. Anaerobic technologies are good agents to reduce greenhouse gases whilst also providing energy.

2.What is made during the process?

Biogas is generated during anaerobic digestion when microorganisms break down (eat) organic materials in the absence of air (or oxygen). 

Biogas is mostly methane (CH4) and carbon dioxide (CO2), with very small amounts of water vapor and other gases.

The carbon dioxide and other gases can be removed, leaving only the methane. Methane is the primary component of natural gas.

The material that is left after anaerobic digestion happens is called “digestate.” Digestate is a wet mixture that is usually separated into a solid and a liquid. Digestate is rich in nutrients and can be used as fertilizer for crops.*

3.Are there many case studies?

Yes, there are examples from all over the world. One such example is the CR&R Anaerobic Digestion Project in Perris, California.

The projects biogas production from this project is around 1,000,000 Diesel Gallon Equivalent (DGE) per year.  You can read more about this project here

4.Is it safe, are there emissions?

Whilst there are health and safety considerations in the operation of an anaerobic digester, the carbon in biogas comes from plant matter that fixed this carbon from atmospheric CO2 so biogas production is carbon-neutral and does not contribute to greenhouse gas emissions. 

Furthermore, any consumption of fossil fuels replaced by biogas will lower CO2 emissions. 

5.When would we get anaerobic digesters in Queensland?

On 27 April 2018, LGAQ Policy Executive members committed to a ‘zero waste to landfill’ target by 2028 for Queensland, underpinned by tried and proved Energy from Waste (EfW) solutions.

In the Queensland State Government’s direction Paper Transforming Queensland’s Recycling and Waste Industry Directions Paper - whilst the paper makes no time reference, it does offer the commitment ‘to explore the development of waste to energy solutions’.  

*Reference: https://www.epa.gov/anaerobic-digestion/basic-information-about-anaerobic-digestion-ad 

Read more: The facts on waste to energy

Local Government Association of Queensland
LG House, 25 Evelyn Street, Newstead Qld 4006


 

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