Residual biomass fuel projections for New Zealand

The goal of this report and the accompanying tables is to describe the woody biomass residue resources in New Zealand by volume, type, energy content, and region over time for the coming 30 years (from 2024 to

2053). The focus is on existing resources derived from established forests, processing, residue streams etc. The report was produced by Scion in the frame of IEA Bioenergy Task 43 (biomass supply).

Read the full paper: “Residual biomass fuel projections for New Zealand”

The resource analysis covers in-forest harvest residues (from landings and cutover), thin to waste volumes from forests, pruning residues, unutilised wood processing residues, municipal wood waste, horticultural wood residues and agricultural (straw & stover) residues, bark from ports and material from shelterbelt turnover. Volumes of A, K and pulp grade logs are also estimated. The recoverable volume of stumps is also calculated, based on assumptions around reasonable limits on slope and soil disturbance. Estimates of currently surplus quantities available from wood processing facilities are included in the assessment. Wood processing residue availability estimates excludes those that are estimated as already being used by the wood processing industry for the production of on-site heat and power. The availability of pulp logs is based on the quantities remaining after meeting the demands of the pulp, paper, and fibre board industries.

There are many sources of residual woody biomass that could provide a low carbon fuel; in forest post-harvest residues being the largest source. However, shelterbelt replacement, orchard turnover, municipal wood waste, straws, bark, wood processing residues, waste thinnings, and prunings from plantation forests etc. are also available. Further there are other resources such as sawmill chip, pulp logs and K grade logs which are typically used or exported but which based on current pricing could reasonably be used as wood fuels.  The long run supply of material that could be considered for wood and other lignocellulosic biomass fuels is around 7.3 million green tonnes per annum. If the materials that currently have a market (sawmill chip, pulp logs that are utilised domestically and export low grade logs) are excluded the total is around 4.1 million green tonnes per annum.

An estimate of current use of these residual woody resources is that around 290,000 green tonnes per annum is being used. However, this figure is likely to increase in the future as coal burning operations look to low carbon alternatives for their heat supply. The declining supply of natural gas from domestic sources along with the associated rising prices for gas may also lead to increased interest in wood as a process heat fuel.