Why Anaerobic Digestion? Reasons to Support Biogas

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Asking: “Why anaerobic digestion?” is a good question. After all, there are other ways to produce renewable energy, and other fertiliser sources many of which can be cheaper in terms of the direct cash to buy them. There are even other ways to dispose of food waste and to prevent farms from polluting rivers and streams.

Read on, and we will explain the many reasons why anaerobic digestion is a “good thing” and to persevere with improving how it is done is well worth the effort.

Now, in case you don’t know what anaerobic digestion the next section contains our explanation of its basic principle of it:

What Anaerobic Digestion Is

Anaerobic digestion occurs naturally, in the absence of oxygen, as bacteria break down organic materials and produce biogas. The process reduces the amount of material and produces biogas, which is mostly methane gas. Methane, in a purer form, is known as natural gas when piped into our homes and businesses, so biogas can be used as an energy source.

Why Anaerobic Digestion? Image of an A.D. facility to show why.
CC BY by Tonyglen14

Biogas plants make more biogas than they consume in order to self-power the equipment they need to run. The spare biogas is usually sold for an income.

Biogas is classed as renewable energy, because the biological material is created from a crop, and the crop is, regrown in a matter of a season, or at most the time for a tree to regrow.

That’s unlike fossil fuels such as oil, coal, gasoline etc., which can only be replaced over aeons of time.

By that, we are talking millions of years, as geological upheavals take place in the earth’s crust.

The technology is commonly used throughout the United States, and many other developed nations, to break down sewage sludge at wastewater treatment facilities.

There are also many thousands of anaerobic digestion (biogas) facilities (“plants”) around the world.

There could be a whole lot more if every farm had one.

Reasons Why Anaerobic Digestion is Worthwhile

Anaerobic digestion (A.D.) is a form of controlled fermentation. As we had already explained, it produces renewable energy and fertiliser sources.

It enables farms to render their farm manure and farmyard manure much safer and less odour forming before it is spread on the land. And, when it is spread the “pre-treatment” provided by the digestion process means that it is better at growing strong healthy plants than the commonly used chemical fertilisers. It has also been shown to produce plants better able to withstand disease and drought.

biogas digester solid digestateIn the past few years, there has been a movement to start adding food waste to anaerobic digesters already in place at wastewater treatment facilities.

In places like England, a whole breed of biogas plants have been built to specifically process food waste, and they produce more energy for their size than most biogas plants. That’s because food has a very high calorific content higher than all other waste and crop-based feedstocks.

The anaerobic digestion of food waste is a good reason why you would do it, because it has many benefits, including:

• Climate Change Mitigation – Food waste in landfills generates methane, a potent greenhouse gas. Diverting food waste from landfills to wastewater treatment facilities allows for the capture of methane, which can be used as an energy source. In addition to decreased methane emissions at landfills, there are greenhouse gas emissions reductions due to the energy offsets provided by using an on-site, renewable source of energy.

• Economic Benefits – Wastewater treatment facilities can expect to see cost savings from incorporating food waste into anaerobic digesters. These include reduced energy costs due to the production of on-site power and tipping fee for accepting the food waste.

• Diversion Opportunities – Most municipalities are investing in ways to divert materials from landfills. This is usually due to reduced landfill space and/or recycling goals.

Wastewater treatment facilities offer the opportunity to divert large amounts of food waste, one of the largest waste streams still going to landfills.

Why Anaerobic Digestion? What is the Purpose?

To Reduce Carbon Dioxide Emissions Causing Climate Change

Methane and power produced in anaerobic digestion facilities can be used to replace energy derived from fossil fuels, and hence reduce emissions of greenhouse gases, because the carbon in biodegradable material is part of a carbon cycle. The carbon released into the atmosphere from the combustion of biogas has been removed by plants for them to grow in the recent past, usually within the last decade, but more typically within the last growing season.

This means that it can reduce the severity of climate change.  Biogas does not contribute to increasing atmospheric carbon dioxide concentrations because the gas is not released directly into the atmosphere and the carbon dioxide comes from an organic source with a short carbon cycle.

Other Reasons for Anaerobic Digestion

Anaerobic digestion can provide an alternative energy source which is promising in the midst of energy scarcity and rising oil prices. Anaerobic digestion can convert waste to bioenergy, renewable fuels and valuable resources and thus divert waste from landfills and reduce greenhouse gas emissions.

With renewed interest in biogas, anaerobic digestion technology has also advanced rapidly in recent years. An advanced, high-performance process not only improves processing time and cost but also the quality and quantity of final products. There are several reasons for using high-performance anaerobic digesters and auxiliary technologies. via www.theecoambassador.com

Is biogas really a renewable energy source?

Yes, biogas is a renewable energy source. It is produced from natural resources that are replenished in short periods of time.

It does end up needing input of fossil fuel energy for its transportation, fuelling the trucks and tractors needed to transport the feed materials and after digestion, spread the fertiliser on the fields. However, plans are underway so that biogas can be used to fuel those vehicles.

Can biogas replace fossil fuels?

Yes, biogas can replace fossil fuels for the production of heat, power and fuel. With additional processing, biogas becomes renewable natural gas that can be used in the same place as fossil fuels.

How does biogas help reduce the effects of climate change?

Why Anaerobic Digestion: Feature image for this article.Biogas is made up of methane and carbon dioxide, which are powerful greenhouse gases. Anaerobic digesters are designed to capture these gases so they do not escape to the atmosphere.

In most cases, the feedstocks used in digesters would have released methane directly as they decomposed in agricultural lagoons or landfills. In addition, using biogas for heat or electricity means that less energy needs to be produced by national fossil-fuel fed, power plants.

This reduces the amount of carbon dioxide emitted into the atmosphere by reducing the need to burn fossil fuels. via www.epa.gov

A great reason to support biogas!

Why Anaerobic Digestion is Already Helping Society

A.D. is already helping society at many installations of the technology. Many different anaerobic digester systems are commercially available. The following is an overview based on organic waste stream type:

  • manure from dairy farms, piggeries, horse stables etc.
  • municipal wastewater treatment and municipal solid waste
  • industrial wastewater treatment.

via americanbiogascouncil.org

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