Food And Forestry Offer Solutions To Tight Power Supply

Regular electricity shortages over New Zealand’s colder months could be a thing of the past if the country diversified its heating sources to include biomass as a fuel.

Brian Cox, executive officer of Bioenergy Association said New Zealanders were getting too familiar with this message from the energy sector at the same time every year.

“The announcement from Transpower that there may be insufficient generation to meet demand on the morning of May 10 is a situation which will become more common if there is too much reliance on electricity for energy supply. This is compounded by the announcement last week by the gas industry about looming gas shortages.

“This is a situation of putting too much focus on a single form of energy.”

With continuing strong population growth, a focus on decarbonising industry, and greater electrification of the vehicle fleet, Cox said New Zealand risks being caught seriously short in electricity generation capacity for years to come.

“And of course uncertainty over the future of the Lake Onslow hydro battery project has been hanging over the market for almost a decade. It has meant while those demand factors have been growing, generators have been hanging back from making any generation commitment, lest they be left with stranded assets if Onslow went ahead.”

While a decision on Onslow has been made for it to not go ahead, long lead times to create more generation capacity create a real squeeze on New Zealand’s electricity generation supply for several more years yet until those new generation assets come on stream.

“If ever there was a time to have a joined-up national energy strategy, that time is now. And if we did, it would be very timely to include the use of biomass alongside electricity as an energy source for industrial processes, like heating and steam generation.”

Food waste and forest slash are two fuel sources already abundant, with ample existing technology available to ensure they could be tapped into with relatively low capital outlay and technical difficulty.

Cox pointed to forestry firm OneFortyOne that recently signed an agreement with Canterbury Woodchip Supplies to take forest slash and turn it into biofuel to replace coal for heating horticulture crops in Nelson.

“That company aims to reduce its slash and forest waste from its forests by 75,000 tonne over the next five years. That is the equivalent of 2000 logging trucks’ worth of timber.”

With almost a third of New Zealand’s household waste comprising greenhouse gas emitting food scraps, there is also an ample feedstock source to enable the supply of biofuel for heating.

The food waste sources for biogas production are diverse, including byproducts of food processing in the vegetable, meat, and dairy sectors, along with the methane gas emissions from landfills largely generated through waste food and organic matter within them.

“A recent PowerCo report on renewable biogas highlights the potential this sector has to contribute to NZ’s climate change goals and energy sources.”

Released in March the report identified the potential for an additional 18PJ of renewable biogas that could be sourced from waste processes, half from the North Island and half from the South Island.

If tapped it means NZ could produce 23PJ a year, representing a reduction of 3.7 million tonnes of CO2 and equating to as much as 27% of NZ’s lower end of targeted gas reduction of 14m tonnes of CO2.

Piped through the gas supply network, it represents about a 9% increase in NZ’s source of renewable energy.

For companies needing gas for food processing, the use of onsite anaerobic digestors to produce biogas for their own use, also represents the next level in energy awareness.

“Between forestry and food waste there is a very deep resource of biofuels that would go a long way to not only help remove this seasonal squeeze on electricity, but also make a major contribution to New Zealand’s efforts to reduce its greenhouse gas emissions profile for the industrial sector.”

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