Short rotation forestry could lower fossil fuel dependency

The findings are said to show that leveraging short rotation forestry will not only diversify regional economies, but also contribute to sustainable land management and generate environmental benefits as New Zealand looks for ways to meet its netzero emissions targets by 2050.

Silviculture and forest carbon scientist Alan Jones says Scion’s modelling shows that short rotation forestry as a feedstock for bioenergy has the potential to replace 6% of New Zealand’s annual fossil fuel demand from less than 1% of the land area.

“We’ve built on research from a decade ago and assessed the feasibility of rapidly upscaling bioenergy production from forests. We’ve found there are regions well-suited to short rotation forestry which provides a real opportunity for communities to transform their economic base and reshape New Zealand’s energy future.”

A key outcome from Scion’s research is a ‘how to’ guide for short rotation forestry targeting landowners, forest investors, and government agencies. It not only outlines the feasibility of SRF but also identifies specific regions most suitable for it in New Zealand.

Scion’s research recommends that short rotation forestry should be established on lower value land (Land Use Capability Class 5-7) in locations where transport distances to processing locations can be minimised. Regions highlighted include the Central North Island, Northland, the East Coast and Otago.

The ideal species for short rotation forestry is Pinus radiata, owing to its rapid growth rates and high degree of adaptability and disease resistance in a range of growing locations. Other options include Eucalyptus fastigata and Eucalyptus regnans for their potential to rapidly yield large volumes of woody biomass from young age trees. Trees are generally planted in dense stands and managed to intensify rates of wood production for renewable energy, such as wood pellets, torrefied briquettes or liquid biofuels for marine and aviation sectors.

SRF is a forestry practice that involves growing and harvesting trees on a short rotation cycle which, according to Scion’s modelling, would ideally be between 12 and 18 years for the production of wood biomass. This is considerably shorter than the conventional 28-year harvesting cycle.

One of the key advantages of SRF is its ability to provide a steady supply of biomass for energy production on relatively economically marginal land, with plantations harvested multiple times. Additionally, SRF can reduce greenhouse gas emissions by displacing fossil fuels and promoting carbon sequestration in the form of sustainably harvested living trees.

Scion’s research responds to signals from the Climate Change Commission that indicate the rising importance of bioenergy from forests in the coming decade.

It also presents owners of low production grazing land on steeper hill country with alternative options to maximise productive capacity and increase economic viability.

Several challenges could impede the future widespread adoption of SRF in New Zealand – primarily low value of bioenergy feedstock under present market conditions. Considerations such as land costs and transportation distances further complicate the potential adoption of SRF bioenergy nationally. To address these challenges, Scion’s analysis proposes integrating the Emissions Trading Scheme (ETS) carbon value of standing trees in SRF plantations into their economic assessment, which provides additional incentives for investment.

Jones says the guide provides a glimpse of what could be possible in the future for short rotation forestry as a vehicle to scale up bioenergy production.