Sun shines on all sources, not just the power of one

Australia’s need for electricity could be met up entirely by renewable energy. A team at the University of New South Wales-Kensington explains which investments it would take. The reason for not conducting so – unfortunately – is of course: money. The exact amount although is contested. Investments, whichever ones to be taken, need subsidies to fund them. We need to get used to the idea that electricity is going to have to be dearer.

This article, written by Michael Bachelard and Deborah Gough was a contribution to ‘The Climate Agenda’ – a partnership between The Sunday Age and website – which let readers vote for the 10 questions they wanted the paper to answer.

THE QUESTION: Solar powered 24-hour baseload power is available now. So why do you allow pollies and shock jocks to get away with saying coal or uranium are still needed for baseload? Has The Sunday Age reported on the fact that the US Department of Energy has identified fuel ethanol from Australian eucalypts as essential for its strategic future? Do your readers know Virgin Blue will get its aviation fuel from gum trees? My point is that people are entitled to details on renewables that are viable now. GEOFF PAIN

IN THEORY, 100 per cent of Australia’s electricity needs could be provided by renewable energy using available technology. But it would be very costly.

A team at the University of NSW (UNSW) has run a computer simulation based on Australia’s hour-by-hour energy consumption in 2010, and the model demonstrated that a combination of solar, wind, gas derived from plant material and hydro-electricity could bear the load.

”There are challenges,” says Associate Professor Mark Diesendorf, who is part of the team. ”But they are solvable. They are not roadblocks, they’re potholes. Some of them are a bit large, but they’re potholes.”

This remains a contentious view. In the Treasury modelling of the federal government’s carbon price scheme, for example, renewables would make up only 40 per cent of our energy supply by 2050. Fossil fuels – coal, gas and oil – would still do the heavy lifting, with power stations equipped to capture the carbon dioxide they produce and store it deep underground.

There is wide agreement that Australia needs more renewable energy sources, but there the consensus ends. Electricity produces 51 per cent of all our carbon emissions now, and to cut this down, the network needs major change. The challenges? Cost and reliability. Governments do not want blackouts and they do not want power bills (or taxes) to rise exponentially to pay for expensive new infrastructure.

At the moment we burn coal in huge power stations to provide the bulk of our power.

Coal power is classic ”base-load” energy – it works 24 hours a day. But this, according to Diesendorf, is both an advantage and a disadvantage. The amount these power stations produce is inflexible because they take a long time to fire up or shut down, which actually encourages profligate use of energy.

The alternative, under almost any non-nuclear, non-sceptics model of the energy future, would be that those coal-fired workhorses are phased out and replaced by a diverse array of smaller generators. The UNSW model is one attempt to show how that might be done, but it illustrates the magnitude of the task. In this model, 40 per cent of the electricity would be supplied by ”solar thermal” power stations. These involve vast arrays of mirrors, which move to catch the sun and focus its energy on a central point. In the case of Spain’s new Torresol Gemasolar plant near Seville, this central point is a tower surrounded by about 2600 mirrors.

The tower captures the heat, where it boils water and generates steam that turns turbines to produce electricity. At Gemasolar, the heat melts a special blend of salts, which act like a vast battery, storing the energy for up to 15 hours and overcoming solar’s main drawback – that it cannot produce power when the sun does not shine. In the UNSW plan, Australia would need to build 130 similar solar thermal power plants.

Rooftop solar panels (known as a photovoltaic system) would provide 10 per cent of our power needs, with panels erected on industrial as well as residential buildings increasing the number of solar panels in Australia thirtyfold.

One-quarter of the power would be provided by wind generators, with 7000 further turbines needed, an elevenfold increase in the number of windmills nationally. The remainder of the power would come from existing hydro-electric plants and biomass – from, for example, burning wood, capturing methane from garbage dumps and extracting gas from grasses and trees. In the model, the biggest challenge came on winter evenings when overcast days stopped the solar generators from working. For these times, large gas turbines – ”like jet engines” – could fire up, burning gas derived from wood or other biological material.

This, says Diesendorf, would ensure the supply was secure. However, the plan would require a large number of new wires and poles, including a new high-grade power line through Broken Hill in NSW, to join South Australia to the main grid in the east.

How much would this cost? ”We haven’t done the economics yet,” Diesendorf says. It would be expensive but, as the world starts mass-producing the hardware for renewable energy, the cost is predicted to come down.

This is not the first attempt to work out how Australia’s energy needs might be met with renewables. A group called Beyond Zero Emissions did it last year using what Diesendorf describes as ”some heroic assumptions”, such as a massive transmission line across the Nullarbor. Beyond Zero Emissions costed its plan at $370 billion by 2020, or $8 per week on the average power bill.

But that is disputed. Martin Nicholson, who wrote the book Energy in a Changing Climate, claims it is more like $1.7 trillion. To pay for this, he argues, the weekly hit to your electricity bill would need to be more like $50.

When the Australian Treasury modelled the country’s energy supply mix in 2050, it assumed $100 billion would be spent on a much more modest move towards renewables but that, for cost reasons, in one of the sunniest countries on earth, solar in all its forms would contribute just 5 per cent. In its modelling, solar thermal power, the backbone of the UNSW scheme, costs four times as much as wind power to build – which is why in its model wind has a larger role, with 13 per cent.

Energy expert and consultant Keith Orchison says Treasury had ”examined it all in detail” and come to the conclusion that ”massive use of solar power is just not going to happen”.

Treasury’s preferred form of renewable energy is geothermal technology, which it said could provide about 18 per cent of power in 2050. This involves pumping water down deep drill holes, where it boils on the hot rocks, and the steam is used to drive turbines.

This illustrates one of the key problems with the move to large-scale renewable energy: the moment you begin investigating it you end up with what people in the industry describe as the ”beauty parade”, where the cost, reliability and availability of dozens of different options are relatively untested, and are therefore argued vigorously.

All, however, are more expensive than coal – though a carbon price significantly reduces the gap – and will require subsidies to fund. Subsidies generally come from the government through the tax system, which is only fair, says Diesendorf, because the existing power stations and transmission networks were built with subsidies of their own.

Under the government’s carbon policy plan, there are three ways in which renewable energy will be subsidised. The Renewable Energy Target requires power suppliers to take 20 per cent of their power from renewable sources by 2020; a $10 billion Clean Energy Finance Corporation is intended to provide funding for developing technology; and the Australian Renewable Energy Agency will administer grants for experimental generation methods.

In Spain and Germany, where the take-up of solar energy is high, the governments use ”feed-in tariffs”, which subsidise producers of renewable energy by paying them top dollar for any power they feed into the electricity network. It’s an option the Australian government has chosen not to pursue, partly because, according to the Productivity Commission, it’s a high-cost way of reducing greenhouse gas emissions.

Some forms of renewable energy are already working. Dr Stephen Schuck of Bioenergy Australia said this country was ”a world leader in biogas, and many of our large landfills and sewage treatment works catch it and burn it to feed electricity into the grid”.

Another biofuel, pointed out by questioner Geoff Pain, is being developed for the Australian airline industry.

By 2020, Virgin Blue wants 5 per cent of its fuel to be sourced from biofuel and the airline is backing eucalyptus mallee from Western Australia to provide it.

Virgin Australia’s manager of sustainability, David White, said there were farmers in Western Australia who had been growing trees for 15 years to combat soil salinity and erosion problems.

Farmers would harvest the trees by cutting them to ground level, then waiting for them to regrow. The wood is chipped to fine particles, which are heated without oxygen, breaking the particles down into solids, liquids and gas. The liquid is used as fuel and should be in Virgin’s tanks by 2014. The solid and gaseous components have other industrial applications. Biofuels, under the Kyoto protocol, are carbon neutral; even though they emit carbon when burnt, the trees suck an equivalent amount out of the atmosphere as they regrow.

White said it would take 2 million hectares of eucalyptus trees to fuel Australia’s domestic air travel, and so far there are just 12,000 hectares growing.

The world is moving in the direction of renewable energy, but whatever happens, according to Diesendorf, ”Electricity is going to have to be dearer. And there’s no point people whinging about it.”

Source: Oktober 2011, The Age

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