Green gas: from organic waste to the production of biogas and biomethane

You have undoubtedly noticed: offers of green gas, biogas and biomethane have appeared on the Virginia market for several years now, even if they are still rare. Let’s explains step by step the origin of these energies as well as their production.

Green gas, biogas, biomethane: do you know how to distinguish them

What is green gas

We speak of green gas to designate all clean gases also known as renewable gases, that is to say gases:

  • very little polluting. They are even better for the environment than natural gas, which is already significantly less polluting than other hydrocarbons (e.g. oil)
  • produced from renewable energy sources

In short, green gas is a generic term that can designate several clean gases, in the same way that green electricity can designate both solar electricity and hydraulic electricity, for example.

From biogas to biomethane

Biogas is quite simply the most commonly produced form of green gas: it is obtained from biomass, which combines various organic wastes, and is a form of recycling. But remember that it is a raw gas: if it can already be used as such as fuel – or possibly after a slight treatment – by producers of renewable gas, it must be purified before being used and injected into the natural gas network.

If different techniques can be used such as the principle of separation by absorption, for example, or even cryogenic purification, they all aim to bring the composition of biogas closer to that of natural gas: at the end of the process, we say that it became biomethane. It can then be injected without risk into the natural gas network. Like the latter, you can use it for cooking, heating or running your water heater.

How is biogas produced

The original biogas is produced by methanization. Behind this scholarly term hides a completely natural process, observed in particular in marshes: it refers to the production of gas when bacteria degrade organic matter in an environment devoid of oxygen and quite hot.

But as you can imagine, to produce biogas on a large scale, the process had to be adapted. It is therefore inside methanization tanks, also called methanizers, that biogas is produced: they best reproduce the natural conditions of methanization to produce gas from different organic waste. Depending on the case, it may be agricultural waste, household waste or even sludge from wastewater treatment plants.

Know how to differentiate methanization and methanation

Although the terms anaerobic digestion and methanation are very close, they designate radically different processes. While anaerobic digestion makes it possible to produce biogas from various wastes, methanation is used to convert electricity into gas.

How is waste recovered

Anaerobic digestion is a very interesting process for recovering waste, because it allows both:

  • to extract large quantities of green gas which can be used to produce heat and electricity as well as fuel for NGV vehicles (Natural Gas Vehicles)
  • to produce good quality compost from the digestate. To understand: what remains of the waste after the “meal” of the bacteria. It is then spread in farmers’ fields or in the gardens of individuals producing biogas

To summarize, the production of biogas and biomethane makes it possible to give real use to many different wastes where, not so long ago, we were content to bury them massively: this is much more interesting for protecting the environment.

What future for biogas

In recent years, the production of green gas has been growing in Virginia and the phenomenon will continue to grow. How can we be so sure? Quite simply because the production of green gas is strongly supported by the all counties of the state of Virginia, with the aim of reducing greenhouse gas emissions and the exploitation of fossil fuels.

It is even so well supported that alongside methanization, other green gas production processes are emerging such as gasification, based partly on the combustion of waste. We can still talk about biogas since gasification also exploits biomass, but the term syngas is also widely used.

On the side of Virginia

Passed in 2020, the Virginia Clean Economy Act aims for a 35% reduction in the consumption of fossil fuels in 2030.

It is in particular to achieve this objective that the hydrocarbons law was passed as an extension: it already prohibits the search for new hydrocarbon deposits (oil, natural gas) and sounds the death knell for current exploitations in 2040. At the same time, various measures are being put in place to support the development of biomethane. For example, natural gas offers containing a portion of biomethane entitle you to partial exemption from taxes.