Bioenergy
What is 'biomass' and 'bioenergy'?
The term 'biomass' is used to describe any kind of organic matter located within the layer of living systems around the planet, commonly known as the 'biosphere'. 'Bioenergy' is the term used to describe the many varied ways of utilising biomass to create fuel for energy. Examples of bioenergy fuels include the leftovers of farming activities, methane gas from landfill, parts of sewage effluent, and compressed waste from household garbage or other streams of fuel. Recent technologies, including some developed in Australia, rely on the use of high temperatures to turn solid material to gas (gasification), with the gases and heat produced then used to turn a turbine to generate electricity.
Different collection methods and energy conversion are suitable in different industries and locations.
Types of bioenergy
Bioenergy can be classified according to either the fuel or the type of technology used to generate the electricity. In NSW, the bioenergy industry is broadly divided into groups investigating collection and energy from:
| Bioenergy type | Examples |
|---|---|
| Methane gas | Landfills and sewage treatment plants |
| Wet wastes | Abattoirs, feedlots and food processing |
| Dry agricultural by-products | Sugar cane waste |
| Municipal mixed wastes | Household garbage and prunings with recyclables removed |
| Forestry by-products | Remnant material from existing sawmills and managed forestry operation |
The technology types currently being used and developed further are gas collection, gasification, combustions and digestion (in the case of sewage). The technologies used to generate energy from organic material is similar to those we use to burn coal. But unlike coal, bioenergy is a renewable resource, as crops can be grown year after year.
Bioenergy and sustainability
In Australia, our current systems for handling the wastes we produce are not sustainable. Landfills are no longer seen as an acceptable way to dispose of urban wastes, and dumping fees are rising accordingly. In rural areas, wastes from agriculture can be an environmental burden in addition to the financial cost for disposal.
Three compelling arguments for investigating bioenergy opportunities are:
- every unit of energy sourced from biomass replaces one that would otherwise be derived from coal-fired power (producing harmful greenhouse gas emissions);
- capturing waste methane prevents it from escaping to the atmosphere where it adds to the heat-trapping gases and the Greenhouse Effect;
- the market in Australia is reaching the point where bioenergy can mean opportunities for extra income from a waste, particularly in rural areas.
All managed sources of bioenergy will result in a net reduction in carbon dioxide emissions, if they replace coal-fired generation. In the case of plantation timbers or crops (like sugar cane), the cycle of growing, harvesting and energy production does not produce or absorb any additional carbon. Carbon stored in the crop is released at harvest, then reabsorbed by the next crop, similar to the natural carbon cycle (see diagram below).
The closed 'carbon loop' for bioenergy
In farming, successful bioenergy projects go hand-in-hand with sustainable agriculture. The ecological viability of a project can involve issues such as appropriate cropping cycles, the distance that fuel is transported, returning nutrients to the soil in the form of ash, or, in some areas, salinity management.
Bioenergy in NSW
Organic remnant material after forestry operations
In Australia, less than five per cent of energy is created using biomass fuels. This is mostly in the form of heat from firewood and bioenergy from bagasse (sugar cane waste) or wood wastes. However, there are a growing number of groups investigating bioenergy technology and finance.
The NSW Government has identified large potential resources for bioenergy in NSW, across agriculture, forestry and wastes. Over 1500 MW of sustainable energy could be produced.
The sugar industry in NSW is a great example of innovation in agriculture, driven by the opportunity to generate bioenergy and sell it into the renewable energy market. The sugar industry has changed its harvesting and processing practices, so that much more of the available biomass is collected.
Canefield biomass in foreground ready for collecting and converting into bioenergy
- Instead of burning off their cane fields before harvest, sugar farmers now collect all of the cane 'trash' as well as the sugar cane, and transport it to the sugar mill, where it can be turned into energy.
- Two NSW sugar mills have installed large power generation plants, efficiently converting all of the bagasse and cane trash into energy.
The NSW Bioenergy Handbook is an information resource on bioenergy resources, technologies, project development and sustainability. Written for the layperson, the handbook provides an overview of bioenergy opportunities and issues in NSW. The Bioenergy Handbook is free of charge and can be ordered through the Customer Programs & Concessions branch by contacting 1300 136 888 or via email on energy.info@industry.nsw.gov.au