|
The paper recycling industry is the major 're-user' of waste wood products in New Zealand. It is estimated that 300,000 tonnes of waste paper is collected and recycled annually. Each tonne of wood fibre used in paper making equates to 17 trees. Thus, in New Zealand the equivalent of over 5 million trees are recycled every year.
Some of the higher quality paper is sorted and exported, but most is used domestically. Most of the waste paper is made up of cardboard and brown papers. A smaller proportion is higher quality newsprint, magazines and the like.
Carter Holt Harvey's paper-making business used 170,000 tonnes of recycled paper in 1999. The Penrose plant in Auckland uses 100% recycled paper to produce corrugating medium and paperboard for cartons.
Other CHH mills that use recycled fibre are located at Kinleith and Whakatane.
An example of a small yet high-value use of recycled wood products is demolition timbers. There is a strong market for reused timber recovered from old buildings. Many of these timbers which were readily available when the buildings were constructed. Kauri and rimu are the most common of these woods. The timber is generally used in housing or furniture construction. It is often holed and stained by rusted nails and can have a weathered appearance that gives a unique and sought-after character.
Bioenergy
Bioenergy is energy that is generated from vegetable material (biomass). This material includes herbaceous and woody plants, algae, agricultural and forestry residues, and industrial and municipal waste.
Energy can be produced from biomass in two ways:
Thermochemical
Combustion: Heat energy can be used to generate electricity or to power industrial processes. Burning fuelwood for cooking and heating is an everyday example of bioenergy use.
Gasification/pyrolysis: The pyrolysis or controlled thermal degradation of biomass produces fuels such as wood-gas and charcoal.
Biological
Fermentation or digestion to produce liquid fuels such as methanol, ethanol, and esters: These products can be mixed with standard petroleum fuels or used on their own. Because these "bio-fuels" can be burned to produce only water and carbon dioxide, they are not environmentally damaging, as are the products of fossil fuel use. Other valuable chemicals can also be produced in the process.
Bioenergy is recognised as being a renewable and environmentally sustainable energy source. Plants can be cropped or farmed indefinitely and provide a renewable source of fuel for energy production. Because plants cycle carbon with the atmosphere, bioenergy production does not contribute to greenhouse gas emissions. Bioenergy is therefore seen as a good alternative to fossil fuels, which are non-renewable and are the main source of the greenhouse gases CO2 and NO2. However, much research is still required to find more suitable biomass types and sources, and more efficient ways to supply and convert biomass into energy.
It is estimated bioenergy provides 14% of the world's primary energy supplies, and could potentially deliver 50%. About 5% of New Zealand's total energy demand, and just less than 1% of electricity production, is supplied from woody biomass. Our forest processing industry generates about 50% of energy needed by burning wood waste such as bark, sawdust, woodchips and black liquor. In 1997, the industry accounted for 11% of New Zealand's total energy consumption.
|