While the challenge is a tough one, Australia can use four strategies to achieve its goal without causing major social, economic or environmental disruption – and at the same time delivering real national benefits.

That is the message in Technology for Sustainable Energy, a paper presented by Dr John Wright, Chief of CSIRO Energy Technology, and Dr Chris Mitchell, head of the CSIRO Greenhouse Program, at the Greenhouse Mitigation Conference in Brisbane.

The four strategies to curb greenhouse emissions are:

• to obtain more energy from less fuel across the whole fossil fuel energy cycle, from production through to power generation
• to sequester (or bury) the carbon released from carbon-based fuels like coal or petroleum, so it does not contribute to greenhouse
• to gradually switch to low-carbon or carbon-free sources of energy, like hydrogen and renewables
• to lower energy demand by improving efficiency in its use in the industrial, commercial and domestic sectors.

The advent of a range of new, more efficient technologies will help to lower greenhouse emissions from fossil fuel-based power generation systems, he predicted.

These include various combined cycle technologies, the use of fuel cells or humid air turbines and gas turbine combined cycle.

"Coal has the highest greenhouse intensity per unit of electricity produced, and its continued use is considered unsustainable in terms of emissions. Yet a rapid shift away from coal may be equally unsustainable on social and economic grounds," Dr Wright pointed out.

The answer may lie in devising a range of new technologies to capture and lock up the surplus carbon produced when coal is burned, he suggested.

"At this stage commercially available technologies for CO2 capture and geological (underground) sequestration are not economically viable, because they would double the cost of electricity. So there is an urgent need to develop more cost-effective technologies."

A second, very attractive option is to develop a hybrid power system, which combines fossil fuels and solar energy.

In Australia the base fuel for this could be methane gas, extracted from unmineable coal seams. Solar energy is then used used to extract the hydrogen for electricity generation and the surplus CO2 then injected back into the coal seams again. Its injection helps to push up more methane.

Fuel switching, from coal to gas, or fossil fuels to renewables is another attractive option already being explored, Dr Wright said.

Renewables already provide almost one tenth of Australia's electricity, but it appears we may have consistently underestimated the extent of renewable resources available.

Biomass – the use of farm and forestry-based fuels, looks promising and could provide a significant share of Australia's transport fuel needs. If carefully planned , the income from biomass fuels could help defray the massive costs of repairing Australia's landscape.

Eucalypt plantings could, for example, be used to produce a range of forest products, including energy, at the same time as combatting landscape salinisation.

Dr Wright said there were many promising new technologies to help lower energy use in industry, commerce and the home.

CSIRO, for example, is currently working on a hybrid vehicle that cuts emissions by more than half, energy-smart windows and buildings, low-energy concrete and construction materials, and devices to "rest" electrical appliances when they are not in use.

"A genuinely sustainable energy system is a major challenge. Its development for a country like Australia will require many interventions and a pluralistic approach to national energy management.

"The main ingredients of this will be greater use of renewables, of embedded and distributed energy systems, aggressive end-use efficiency and development of new technologies to enable continued use of fossil fuels until the transition to sustainability is complete."

Dr Wright said it would require a combination of market and regulatory measures to achieve this.