By Sebastian Klein
In his recent book Atmosphere of Hope, Time Flannery points out that at current rates of greenhouse gas (GHG) emissions, in addition to existing atmospheric GHG concentrations we are quite certain to overshoot 2°C of warming by the end of the century. This even accounts for successful attainment of current national emissions targets worldwide.
The premise of his book is that we will need a suite of innovative technologies that do not have likely side-effect impacts on other vital biological and geo-physical systems. He discusses a range of technologies, but one that stands out is the use of bioenergy.
As a wise crack at one conference stated, the only proven carbon sequestration technology anywhere near scale-ability or commercialization is photosynthesis. However, the area of reforestation required to restore carbon concentrations to levels similar to pre-industrial levels is, according to Flannery, up to 7.5 million square kilometres, the area of mainland Australia.
Those trees then need to be nurtured to maturity and sustained for at least half a century. A big task – even in the more fertile corners of the planet.
Bioenergy and production of biochar is, in my view, a critical candidate for the suite of technologies required to not just reduce GHG emissions, but to mitigate the existing concentrations of carbon in the atmosphere.
The chief reasons for this view are numerous, relating to the multiple outcomes produced by systems utilising both purpose grown feed-stocks, as well as those using by-products. A few of these reasons are elaborated below.
Firstly, the cumulative effects of plantations designed for energy and char production result in ongoing sequestration unlike many other technologies that simply reduce emissions.
For instance, a perennial crop will increase root-mass and soil carbon alongside carbon used in processing. The most viable systems also produce other ‘bio-products’ that can be counted as either supplanting carbon emissions or sequestering them (bio-products are simply those made from recently living carbon, eg. furniture or substitutes for fuels and chemicals otherwise derived from fossil substances).
Secondly, bio-energy and bio-char provide an exciting opportunity for rural economies and particularly farmers to become more productive and profitable in the context of the new ‘carbon-economy’.
By using by-products (for instance crop residues) from existing practices, or by converting marginal, or under-utilised land for bio-crops, land managers can produce additional income for their farm. In some cases this is a feasible consideration without an effective market-based carbon mechanism, and would become more attractive in such a market context.
Third, bio-energy processes can utilise by-products that currently are simply allowed to decompose, emitting GHGs without a productive return. Throughout industry carbon is produced in a myriad of by-products with little or no value retained and subsequent emissions from decomposition allowed to enter the atmosphere. Bioenergy processes can utilise the energy inherent in these products and in some cases render nutrient value fit to be returned into the productive cycle. A good example of this was found among the numerous abattoirs that installed methane capture processes for waste from that industry. This allowed them to reduce reliance on energy from fossil fuels, but also produced a nutrient rich material able to be returned to the agricultural cycle.
Finally, purpose grown bioenergy-crop systems can be designed to augment and support existing efforts to promote and protect biodiversity, providing buffers and additional (albeit time-limited) habitat around re-vegetation efforts.
One of the barriers to the uptake of bioenergy remains a view that vegetation for biodiversity and plantations for bioenergy are mutually exclusive. In fact, due to the long rotation of many bioenergy crops, they provide an important additional reserve of habitat, which can be designed to optimise the effect of re-vegetation, bio-links and remnant habitat.
Bioenergy presents an opportunity to enrich many aspects of our agro-ecosystems and economy. The reasons for supporting its uptake are many and varied beyond those mentioned here and as a concept it represents a diverse and growing stable of systems and technologies that could support our economy while assisting in the campaign to reduce atmospheric GHGs.
Flannery, T. (2015). Atmosphere of Hope. Text Publishing, Melbourne.