Bioenergy Basics

Bioenergy is renewable and sustainable energy made from biological materials such as:

Plants such as corn, soya and sunflower (known as biocrops)
Wood chippings (i.e. wood waste)
Rice husks
Commercial, municipal and industrial waste
Manure and sewage.

These materials are referred to as biomass. Sometimes they are called biofuels but this term is more often used to describe liquid bioenergy fuels, such as biodiesel.

Bioenergy accounts for the majority of renewable energy produced globally.

EBRI focuses on producing bioenergy from waste

There are numerous issues associated with growing biocrops for bioenergy. These are:

1. The production of some biofuels has been linked to high levels of carbon emission.

For example making ethanol from corn can generate large quantities of greenhouse gases through the use of tractors, fertilisers and processing plants.

2. The incineration of fuels

In many cases, biocrops are used to produce a biofuels or charcoal (known as biochar) that is then incinerated for energy. This leads to the emission of CO2 and other pollutants and makes it unsuitable to have such a power generation unit set in a conurbation area.

3. The use of wood

Many argue that wood would be better used to produce building materials and furniture where it would store the carbon as opposed to using it to produce bioenergy.

How do you produce bioenergy from waste?

The main process involved in turning waste into bioenergy is called pyrolysis. The word is coined from the Greek-derived elements pyr "fire" and lysis "separating". Pyrolysis is essentially the process of using heat to break down waste into a form of charcoal known as biochar and synthetic gas (a mix of carbon monoxide, hydrogen and very often some carbon dioxide).

Pyrolysis takes place under elevated temperatures (above 430°C) and pressure. The exact conditions depend upon the biomass being used, for example agricultural waste is typically processed at temperatures between 450 and 550°C.

The synthetic gas (syngas) produced from the process can be burned directly in gas turbines to produce electricity. The biochar makes an excellent fertiliser thus storing the carbon in the ground for thousands of years. Alternatively, it can be burnt as fuel or used in the food industry to replicate smoky flavours or even used to produce bio-hydrogen which can be used to power hydrogen-fuelled cars.

The whole process is not only carbon neutral; it is actually carbon negative as it removes carbon and stores it in the form of biochar. Biochar used as fertiliser holds carbon in the soil for thousands of years.

Pyrolysis also offers the opportunity to process contaminated waste which cannot be put into landfill. The process separates out the contaminant, such as organic mercury, which can then be sold back asa valuable material to the chemical industry.

Another potential benefit is growing energy grass on contaminated land to decontaminate the area. Note: this is the only circumstance in which biocrop is used in the process. The energy grass naturally draws the pollutants out of the soil thus returning the area to its natural state. The contaminated grass can then be put through the pyrolysis process allowing the contaminant to be removed, isolated and resold along with the production of heat and electricity as a by-product.

The production of bioenergy from waste is a well-established technology.

Find out how bioenergy can help your business or organisation reach its targets. For more information on the producing bioenergy from waste go to bioenergy from waste.