Biomass Electricity

Discussion

Electricity can produced from biomass such as plantation fuelwood, which can be burned to run steam-turbine electricity generators, or turned into gas or methanol before firing a turbine.

A fuelwood plantation can be a source timber and aromatic oils as well as fuelwood, and can also be used to control salinity.

Biomass electricity is potentially greenhouse neutral, and can have low impact on natural ecosystems if the fuelwood is derived from plantations that host biodiversity. Fuelwood from old-growth forests is both high-impact and not greenhouse-neutral.

Electricity from wood-fired steam-turbines should be generated close to the fuel source, due to the energy costs of transporting solid fuelwood over longer distances, which are higher than transmitting the electricity generated. (Converting the fuelwood to gas or methanol, and then transporting it via pipes, may have lower energy costs.)

On the other hand, the electricity should ideally be generated in a cogeneration plant, with the waste heat used for other purposes such as industry, or heating.

This suggests a need for small scale, heat-using industrial facilities or urban settlements, than can be located adjacent timber or fuelwood plantations.

Readings

Mandatory Renewable Energy Target

Natural Resources, Forests and Agriculture - Prospect Analysis - Electricity Generation - Australian Greenhouse Office

Coal is likely to remain the cheapest fuel source for base-load electricity generation in Australia for many decades. However, the Mandatory Renewable Energy Target has paved the way for new projects for electricity generation from renewable sources such as wood waste.

The Target seeks to increase the contribution of renewable energy sources in Australia's electricity mix by 9,500 GWh per year by 2010.

The legislation requires electrical retailers and larger users to obtain increasing amounts of their electricity from renewable sources, either directly or by buying certificates from other producers, commencing from 1 April 2001. Currently, renewable certificates are valued at $40/MWh to the generator.

This legislation has guaranteed a market for additional electricity generated from renewable sources. Tree crop biomass can compete for market share with reasonable prospects of success, as it is potentially one of the lower cost sources of renewable electricity. The commercial advantages of supplying electricity at remote locations on the grid (or even off-grid), and receiving higher payments for using a renewable fuel source, should enhance the profitability of electricity generation from tree crop biomass in mid and low rainfall zones.

Electricity generation is ideally suited to using residues in an integrated processing plant. It could be generated from low rainfall plantings either via a conventional power station or via small-scale gasifiers and micro turbines. These smaller systems are potentially very efficient, particularly for local use.

Biomass Electricity from Timber Plantations

Biomass Beckoning - Australian Energy News, Issue 7, March 1998

900,000 hectares of ex-grazing lands planted with fast growing eucalyptus species, (that is less than 2 per cent of the area currently sown to pasture crops annually), could sequester some 600 million tonnes of CO2 per annum equating to a 10 per cent reduction in greenhouse gas emissions from Australia.

While up to two thirds of that CO2 would be released when the timber was eventually harvested, if the wood wastes were turned into electricity then other more carbon-intensive means of electricity production would have been avoided, significant timber resources developed and harvested, in the process locking up some CO2, and the sale of electricity would greatly improve the economics of that timber production.

Wood waste is available in large quantities and could produce electricity for less than the cost of coal fired electricity. Wood residues could be delivered to industrial boilers for $0.25c/MJcompared with black and brown coal at between $0.27-$0.29c/MJ.

The Federal Government's co-operative plan with the National Association for Forestry Industries, 'Plantations - 2020 Vision', is intended to result in a tripling of Australia's plantation estate by 2020.

Biomass Electricity from Old-Growth Forests

Burning Wood for Electricity - ABC, 21 August 1999

Burning Trees for electricity: is renewable energy as green as we think? As biomass energy takes off around the world a battle is brewing over burning native forests.

Forests in the Furnace - Nature Conservation Council of NSW, 12 June 2000

There is no benefit in switching to biomass energy if crop production destroys native ecosystems, reduces biodiversity, pollutes wetlands and waterways with fertiliser and chemical run-off, and exacerbates salinity problems.

Electricity generators in NSW have begun substituting coal with sawdust and woodchips from native forests. While the burning of timber releases carbon in the same way as coal, burning wood allegedly enables the industry to reduce their greenhouse emissions. This is because the carbon accounting methodology only counts the emissions from coal, and not from wood.

Carbon stored in forests is far more than just that found in the trees. Up to 80% of the carbon stored in an old forest is in the soil. Logging operations seriously disturbs the delicate balance of forests and releases this stored carbon.

Biomass - Burning Forests For Power -Wildnerness Society, 31 August 2001

Electricity producers are proposing to substitute coal with native forest wood products as a way of "reducing greenhouse gas emissions". While the burning of timber releases carbon in the same way as coal, the electricity industry claims that biomass is regarded as greenhouse neutral because new trees are grown to replace those which are logged.

The energy industry and the government describe what is being burnt simply as 'forest waste'. However [this could include]: old trees, not suitable for sawlogs; silvicultural thinnings (trees removed to promote the growth of sawlogs; sawdust, bark, heads and butts (these are uneconomical to woodchip and would be unlikely to be used as biomass); whole trees currently used for woodchips.

Library

Auspine Renewable Energy Commercialisation Project - Australian Greenhouse Office - Auspine is preparing to build a 60MW biomass-fueled power station at Tarpeena, near Mount Gambier, South Australia [that will use annually] about 600,000 tonnes of [plantatation thinnings and sawmilling waste from existing pine plantations]. Cost: $90M. More Data...

2006.6.14