Case studies

The conversion of the Paraparaumu Sewerage Sludge Drying Plant from diesel to wood will offer Kapiti Coast District Council the opportunity to slash its fuel costs at the site from the current level of around $575,000 in 2008, to as low as$115,000 in the first year of operation.

This report reviews the installation of small-scale renewable electricity generation systems on five islands around New Zealand, on Department of Conservation bases. The report reviews the economics and performance of the systems, the potential benefits that accrue from switching from diesel-fuelled generation to systems incorporating photovoltaic modules and micro hydro units, and sensitivity analysis to test the economics under a number of scenarios.

In May 2008 Cashmere High School switched from coal to renewable wood energy to heat its site.

The new boilers produce around five times less particulate emissions than a typical school coal boiler. Carbon emissions have reduced by 216 tonnes per year. The wood-fired system is also 14% more efficient.

"There used to be soot and ash in the gutters. Now we just have clean, clean emissions," says Cashmere High support services manager Roger O'Regan.

A 50kW wood pellet-fired boiler is proving considerably cheaper than electricity for heating the Bay of Plenty‘s 30 bed Titoki Healing Centre.

Fully automated and fed by a 3-tonne hopper topped up by the truckload, the system operates virtually hands-free.

Installation cost around $80,000. That compared more than favourably to the other main option, heat pumps, at around $90,000. Running costs are even more competitive at about $4,400 annually, almost a third of the costs estimated for running heat pumps.