Community Energy For Dry Year Reserve, Resilience And Carbon Sequestration

Today’s electricity market has suppressed some of the most carbon-efficient and cost-effective energy options, namely community energy solutions.[1] Labour’s energy strategy must judge these on their merits before committing funding to their $4 to $6 billion proposal for pumped hydro storage to fill gaps in a “100% renewable electricity supply”.

An alternative concept is in urgent need of funding: use of bioenergy in regional energy facilities to supply and store energy and even sequester carbon, enabling flexible electricity supply with extra for winter peaks and dry years.

Community energy would begin with an immediate expansion of home energy retrofits, improving the health and productivity of the poorest New Zealanders. A mere $1 billion would restore the original Greens’ home insulation scheme. This would cut winter peak demands, saving hundreds of millions of dollars of transmission investment, and employing hundreds of skilled advisors and workers.

A whole new concept of flexible energy supply would be based on bioenergy, both biogas from food wastes and energy from woody biomass. In urban areas these facilities would be based on landfills, capturing some 3 PJ per year of landscaping wastes now being dumped[2]. Elsewhere, energy centres would utilise local biomass resources, including orchard and agricultural wastes, and augmenting these with trees planted and harvested as part of regenerative agriculture schemes.

These energy centres would become centres of excellence in research, development and commercialisation of new concepts of true carbon-zero energy. Ultimate employment prospects would be many thousands of people at all levels of skill.

Woody biomass can not only cogenerate electricity and heat, but can sequester energy in the form of biochar which lasts for thousands of years in the soil, and improves the yields of farmed products. A less refined product, biocoal (torrefied wood), can substitute for coal in greenhouses, providing carbon dioxide as well as heat to stimulate yields.

Industrial heat now supplied by coal would be far better supplied by local biomass resources, as using wind or solar power for industrial heat wastes thermodynamic potential and increases vulnerability of the economy to dry year shortages­.

Wood gasification and flameless combustion has been demonstrated in New Zealand; its potential for smokeless burning of green wood or wood chip makes this an outstanding candidate for providing extra energy in dry years. In a regional energy centre, additional forestry wastes could be collected or local trees harvested in dry years, and electricity output could be maximised at the expense of sequestering carbon as biochar.

It is essential that the $30 million study of pumped hydro includes a fair and thorough examination of the bioenergy options for providing flexible energy supply, so that shortages of solar and wind electricity supply can be made up by local energy sources.

[1] MacArthur, Julie L. and Berka, Anna: (Re)charging communities? Three energy futures for Aotearoa New Zealand, PREPRINT NZ Sociology, Vol 35(3), Dec. 2020

[2] https://www.usewoodfuel.org.nz/documents/resource/Wood-residue-resources-report-2017_Revised.pdf

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