A future carbon constrained society will still require carbon based products and services, such as high energy density fuels, organic materials, chemicals and reductants, which are now primarily sourced from fossilised coal, oil and gas.

Biomass is the originator of fossil carbon sources. It can therefore produce similar energy and material products with the distinction that the carbon in biomass is recently sourced from the atmosphere and therefore part of an intrinsically balanced carbon cycle.

Biomass explained

There are broadly four main types of terrestrial biomass:

* Oils such as oil palm tree and canola seed * Soluble carbohydrates such as sugars and starches * Insoluble carbohydrates (proteins) * Lignocellulosic material (woody biomass).

Lignocellulosic material (woody biomass) is the most common form of biomass in agricultural, industrial, municipal, forest and natural environments. Tree based lignocellulosic biomass can be harvested on demand, therefore offering the most stable and scalable primary resource for biomass based renewable energy technologies.

There are six generic technologies for energy conversion:

1. Direct combustion for power 2. Anaerobic digestion for methane rich gas 3. Fermentation of sugars for alcohols 4. Oil extraction for biodiesel 5. Pyrolysis for biochar, gas and oils 6. Gasification for syngas.

These can then be followed by an array of secondary processing options depending on the required end product.

Thermal technologies such as direct combustion, pyrolysis and gasification, can effectively process all forms of biomass, including complete utilisation of lignocellulosic materials. Combustion and gasification of biomass for heat and power have the added advantage of proven commercially viability.

Competing technologies

The primary difficulty with biomass for electricity generation is the competition with other sources of renewable energy. The majority of actual and potential renewable energy output in Australia from non-biomass sources – such as wind, hydro, geothermal and solar – is electricity. This means that there will be significant competition for biomass-based electricity generation projects. Conversely, none of the competing technologies are able to make gas, liquid or solid energy products, creating a market opportunity for such an enabling technology.

Pyrolysis of lignocellulosic materials provides a flexible platform for solid, liquid and gas outputs roughly analogous to their coal, oil and gas fossilised counterparts. Pyrolysis outputs are mainly used in basic heat and power applications, with developments underway to produce higher quality transport fuels through the further refining of biocrude. Pyrolysis char (biochar) can be used for energy, metallurgical reduction, activated carbon, or for carbon sequestration in soils.

The key challenge for pyrolysis is that there are still relatively few commercial pyrolysis operations using biomass feedstocks. Once these development challenges are overcome, it is likely that pyrolysis projects will out-compete biomass for electricity generation projects because of the increasing value of liquid fuels.

Future challenges

The success of bioenergy projects depends fundamentally on sustainable biomass supply, techno-economically viable processing and a societal licence to operate. The report presents a bioenergy project evaluation tool, developed by Crucible Carbon, to help address critical project issues such as land, water and biodiversity management. The tool highlights keys to success, including minimising the use of prime agricultural land, maximising soil fertility and carbon sinks, ensuring balanced nutrient cycles and water budgets while promoting regenerative practices with respect to native habitats and ecosystems in impacted regions.

There are strategic sustainability advantages of bioenergy sourced from multispecies native assemblages because it has the potential to be carbon neutral, or even better (carbon negative) when combined with sequestration. However, robust carbon and sustainability accounting on a complete life cycle basis is needed to defend the environmental credentials and greenhouse benefits of bioenergy projects.