13 May 2010

Adding Value to Raw Biogas by using Upgrade Process Technology

Biogas Upgrading Technology - Cleaning Raw Biogas Into Usable Natural Gas

Richard Belcher has written a great article explaining the range technologies used to upgrade raw Biogas. Using these techniques it is possible to “upgrade” (purify) raw biogas to make a much less corrosive gas which is essentially the same in its composition as natural gas as used in homes and factories and distributed in gas pipe networks.

He explains how anaerobic digestion systems (that convert waste material into biogas) are rising in numbers worldwide. Rural farmers are building these plants so far mostly to use biomass to produce energy to help power their farms. But, upgrading can add more value to their raw biogas and even allow them to produce good quality fertilizer and natural gas from waste materials like manure in a cheap and sustainable way.

Raw biogas when produced by the digester is roughly 60% methane and 29% Co2 with trace elements such as Hydrogen Sulphide (H2S). H2S is highly corrosive and toxic and can kill you at even low concentrations if breathed in.

By contrast, natural gas is 99% pure methane clean burning and non toxic, which makes it a far more valuable product. The digester owner can sell this gas for use as a fuel gas for machinery. Corrosion worries are gone after upgrading and this gas may, (at least in theory) even be pumped in the local gas grid pipeline.

There are several methods and technologies by which upgrading can be achieved, and these are:

- Water Washing
- Pressure Swing Adsorption
- Polyglycol (Selexol)
- Chemical Reaction.

So, a Biogas-Digestor is only the beginning of the process to convert biomass into useful high quality natural gas. As digester systems become more common around the world and people begin to catch on to biogas as a renewable source of energy, no doubt we will see more of these systems become available and more innovative designs will yet be developed.

This is only a part of Richard's highly informative article Upgrade Biogas here.

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