Bioenergy, Renewables, Waste-to-energy

Using biomass to get to net zero

Proper utilisation of heat generated in natural processes can see us harness much more energy, writes Shaun Scallan.

We all know that our dependence on fossil fuels is not sustainable. Net carbon emissions to the atmosphere must be reduced to zero by 2050.

Two ARENA initiatives are seeking to establish pathways to net zero emissions. The first is a study aimed at moving industry off gas, toward electricity and other energy sources, specifically process heat. Process heat is heat used to dry, cook or otherwise treat materials in a wide range of manufacturing processes.

The second is the Bioenergy Roadmap, which is seeking to establish a plan to increase the value from our abundant biomass. This biomass is currently a wasted opportunity to generate renewable energy and process heat that will help reduce the dependence on fossil fuels, particularly gas.

Biomass is organic material that comes from plants and animals, and it is a renewable source of energy. It is part of the Earth’s natural capital, where natural capital can be defined as the world’s stocks of natural assets, which include geology, soil, air, water and all living things.

Sources of biomass include forestry, agricultural crops, animal manure and human sewage. By targeting the resource streams that are not used, or “wasted”, we have a resource that can deliver more value to the economy and the environment.

The Clean Energy Finance Corporation estimates a potential investment opportunity of between $3.5 billion and $5 billion in energy from urban waste, agricultural waste and forest residues.

In international comparisons, Australia derives around 4% of total energy consumption from biomass sources. This is in contrast to the EU, where biomass accounts for about 10% of energy consumption. By 2030, the EU expects nearly €60 billion in economic activity from bioenergy projects and 550,000 direct and indirect jobs.

Heat and electricity from biomass

Process heat can be obtained via pyrolysis, where biomass is heated in a low-oxygen environment to produce products such as biochar and biofuels. Currently the economics of pyrolysis and biochar are challenging because the biochar market is in its nascent stages, but there seems to be a solution.

During the pyrolysis process heat is generally sent up a chimney to be wasted. If there were a heat engine that could transform this heat to electricity efficiently, this would make a compelling case for an integrated bioenergy power station using pyrolysis.

Enter Capricorn Power’s new heat engine, which is currently being commercialised in Geelong, Victoria. The engine is designed to convert more heat than conventional heat-to-electricity solutions and the technology uses no water or toxic materials in its conversion of heat to electricity.

The need for more resource usage efficiency has driven this development, which is based on a patent pending process innovation using a variation of a thermodynamic cycle called the Barton Cycle, named after Capricorn Power’s CTO Dr Noel Barton.

To explain the process, hot gas – for example exhaust from the pyrolysis process – is brought into the heat engine which then compresses and expands the gas to drive opposing pistons of the “engine” to rotate a shaft that then drives a generator to create electricity.

The process sounds simple. The trick is to do this in a way that extracts two-to-three times more energy than existing comparable processes.

More than just carbon capture and storage

One of the products from pyrolysis is charcoal called biochar, in that it comes from biomass. The application of biochar ranges from agricultural usage through to creating higher value products, such as activated carbon.

When used in soils, biochar is a carbon sink that can last thousands of years. This is truly carbon capture and storage in its simplest and most effective form. Make biochar, put it into the soil. It’s done.

In addition to being a carbon sink, biochar can provide soil nutrients, improve retention of water and nutrients and increase crop yields. Local water quality can also be improved by keeping nutrients like phosphorous and nitrogen in the soil, rather than have it remain in runoff that can upset ecosystem balance in waterways.

It may sound like a magic bullet for restoring the land because that is what it is. I’d call it CCS+.

Enabling the circular economy

An efficient heat engine enables the utilisation of resources that would otherwise be wasted and therefore emulates nature in that there is no concept of waste.

The underpinning principle of the circular economy is that we create closed loops which continuously circulate resources with no waste. These perpetual resource cycles are nature defined, creating and recreating the world in which we live in a constant dance of renewal.

Rather than cycle the nutrients endlessly, circular economy processes allow us to repair the damage we have done, without waste, thus restoring the natural capital of the earth.

By mimicking nature in the way we deploy technology, our human activities become part or, rather, an extension of the biosphere. This can add to our natural capital rather than degrade it, as our current application of technology does. 

It is all in our hands. The choice for a better world is our next project away.

Shaun Scallan is head of products at Capricorn Power.


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