Bioenergy should form a fundamental part of any country's energy strategy, more so in New Zealand, where agriculture accounts for half of all GHG emissions. When we include GHG emissions from municipal waste and transport, these account for three-quarters of all of NZ's emissions. The fact that bioenergy in NZ has been a non-starter thus far is counter-intuitive.

Consider an excerpt from this paper, titled Bioenergy Options for New Zealand, published in 2008: 

"The potential benefits from bioenergy extend well beyond the energy sector, crossing into areas of sustainable land use management, regional development and national economic development. Any shift from fossil energy to bioenergy will require much more than research. Technology demonstration, infrastructure, industry partnership, the right policy environment and consumer perceptions must all be addressed. Given full government backing and careful management, this bioenergy vision may be the national sustainable development opportunity that could enable New Zealand to reach carbon neutrality, without sacrificing economic well-being."

 While the focus was largely on the potential of NZ's forestry sector, extending to purpose-grown forests, it did acknowledge the role of anaerobic digestion, especially for treating municipal wastes and effluent from meat-packing in achieving the above-stated aims.

Anaerobic digestion - or more specifically anaerobic co-digestion - can and should form a key part of NZ's bioenergy strategy. The beauty of this technology lies in its simplicity: at scale it is cheap, it diverts waste away from landfill, it offsets emissions and most importantly it can work with existing infrastructure. Upgraded biomethane is a direct substitute for natural gas and has application in industrial and domestic contexts. Moreover, biogas can also substitute coal for electricity generation, thus providing a renewable energy source that can extend the life of Rankine-cycle thermal power plants while still supporting base-load requirement of the grid.

Moreover, the process produces a valuable co-product, a nutrient-rich and pathogen-free organic fertiliser, which can substitute chemical fertiliser, improve soil quality and requires far less water for irrigation, thus leading us through a virtuous cycle.

The policy environment in NZ has evolved significantly since 2008, with key initiatives such as the Zero Carbon Act, the Freshwater Bill and the proposed enhancement of the Resource Management Act, requiring farmers to provide a comprehensive Farm Environment Plan.

The way forward will require a well-coordinated approach at the highest levels of government, including but not limited to MBIE, MFE, DOC, MPI, MOH etc. This is systems-level thinking, but absolutely necessary in the context of the stated aspirations of NZ to be carbon-zero by 2050.

Covid19 has provided an opportunity: if we extend the study of epidemiology to financial theory, we recognise that the loss of a single human life has an absolute value, which is infinite. We can justify measures such as lockdowns and closed borders, because the associated costs do not compare to the absolute value of human life.

However, even without such philosophical arguments, the financial metrics stack up. The life-cycle costs are far lower when you add up the avoided costs of landfill gate fees and their associated levies, and the revenues earned from sale of energy, nutrients and carbon credits. The land required is less than what a landfill requires, and in the medium to long term such an approach can rehabilitate and regenerate land that would otherwise be lost.

Therefore, any further deliberation is only going to make achieving these targets more difficult. Why put off until tomorrow what you can do today?