CHH looking at energy potential of 'black liquor' waste

Carter Holt Harvey Pulp and Paper chief executive Brice Landman says the company is keeping a close eye on new, but unproven, technology for recycling some liquid waste from pulp mills as a fuel.

Black liquor -- the liquid material that remains after pulp logs are cooked in the production of chemical pulp -- contains approximately 70 per cent wood component.

Recent technology developments have enabled another major forestry exporter, Sweden to announce that it will cut oil imports by 40 per cent within the next five to 10 years.

Much of the fossil fuel will be replaced with a fuel derivative from the pulp and paper industry waste-stream.

Mr Landman said: "We are obviously interested in these processes and are keeping a close eye on developments."

He said the black liquor produced at the company's mills was already burned for energy purposes.

"At both the Tasman and Kinleith mills spent black liquor, wood waste and natural gas are burned to produce steam and generate electricity and only small amounts of oil are used in the pulping process," Mr Landman said.

A Swedish company, Chemrec, has demonstrated that gasification of the black liquor by boiling it can produce a fuel, dimethyl ether (DME) - that can drive conventional diesel engines after only slight modifications.

"There's no doubt that within five to 10 years it will be possible for the general public to drive cars fuelled by DME," the company's technical director Ingvar Landalv said.

Swedish truck manufacturer Volvo has already developed a prototype truck powered by DME.

Rotorua-based company Scion (formerly Forest Research) is developing sustainable biomaterials for future generations, though it has no current programmes investigating liquid biofuels.

But principal scientist Roger Newman said that the sector was "certainly an area of interest" for the state science company.

Dr Newman said that DME was not the only fuel that can be derived from the pulp and paper industry.

"An 87-octane fuel called MTHF can be made from paper mill sludge, sawdust, or recycled paper".

Two important liquid fuels can also be derived from trees.

Timber waste broken down by heating it in the absence of oxygen produces carbon monoxide and hydrogen that can be further refined to give large volumes of methanol.

And ethanol can be recovered from wood and turned into an alcohol to be added to conventional petrol.

Brazil's petrol supplies have included 20 per cent ethanol -- from sugar cane waste -- for the past decade.

In New Zealand, Fonterra's Edgecumbe dairy factory has been distilling ethanol from waste whey to blend in petrol.

Fonterra successfully tested petrol mixed with 10 per cent ethanol in a 1.8-litre car. The blend provided by Gull Petroleum was approved by the Environmental Risk Management Authority (Erma).

Last week the Government announced that it will set up a legal framework for the use of petrol/ethanol blends.

The Edgecumbe ethanol plant produces 30,000 litres of ethanol a day and five million litres in a dairy season and Fonterra also produces ethanol at Reporoa and at Tirau.

- NZPA