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Published: 2011

Growing a green fuel industry in Australia

Joely Taylor

Can Australia grow an economically and environmentally-sustainable biofuels industry on waste biomass? Joely Taylor investigates.

Feedstocks for lignocellulosic conversion to biofuels include agricultural residues, such as wheat stubble, and construction industry waste.
Feedstocks for lignocellulosic conversion to biofuels include agricultural residues, such as wheat stubble, and construction industry waste.
Credit: CSIRO

With the potential to cushion Australia from the shock of fluctuations in oil prices and fossil fuel availability, a home-grown, waste-fed biofuels market is seen as an environmental opportunity, as well as an economic and fuel security issue. New, ‘second-generation’ biofuel production technologies developed around the world are being assessed for their technical and economic feasibility.

These second-generation technologies (see second box below) convert lignocellulosic1 biomass to a range of biofuels in many different ways. Three main conversion technologies are gasification, pyrolysis and hydrolysis (see second box below). The feedstock for this conversion includes agricultural residues such as wheat chaff and sugarcane bagasse, forestry residues and urban wastes diverted from landfill. One advantage of second-generation technologies is that non-food feedstock can be converted to biofuel, potentially reducing the competition for agricultural land.

Many of these second-generation conversion technologies are now reaching the commercial demonstration stage. This provides a chance to iron out any remaining technical issues and prove the processes in industrial mode. The main impediment to the successful commercial implementation of these technologies is the economy of scale. In other words, the challenge is to find the balance between the cost of the production process and the availability and cost of the required volume of biomass. Biofuels must be cost competitive with fossil fuels, because most consumer decisions are price-driven.

Does Australia have a competitive advantage in biofuel production?

For the past few years, scientists from CSIRO’s Energy Transformed flagship have been researching biomass production suited to second-generation conversion technologies, and current sustainability issues and economic scenarios. Their recent research findings give support to the view that it may be economically feasible to produce and use biofuels from available residue and waste streams in Australia.

CSIRO ecological economist, Dr Luis C Rodriguez, led a case study of the scenario of an ethanol plant situated in the Green Triangle – an area of approximately six million hectares in south-west Victoria and south-east South Australia. The study found that, given current oil prices and zero excise for ethanol, such a plant could be viable if the forest and crop residues cost at the plant gate were less than $74 per tonne.

‘The Green Triangle is one of the most promising Australian regions for biomass production,’ says Dr Rodriguez. The study region was selected for analysis due to its well-developed forest industry and level of grain production, as well as the availability of roads and infrastructure.

‘A focus of the study was to estimate the costs associated with each of the different residue streams, their competing uses and demand, and to link those feedstocks with geo-referenced information about their location and the transport distances and costs,’ explains Dr Rodriguez. ‘The study indicated that, under current economic conditions and policy, only about 20 per cent of the potential biomass produced in the region could be used for energy production in an economically viable way.’

The break-even point between feedstock price and the size of the biofuel plant can change depending on the assumptions around cost of excise and the cost of a barrel of oil. The cost of producing ethanol from biomass feedstock in the Green Triangle would be $0.64 per litre, with a pump price of $1.24 per litre after adjusting for energy content.

‘The different break-even prices and abundance of biomass for ethanol production in the Green Triangle region suggests that an ethanol industry could be viable under different combinations of fuel tax rates and oil prices,’ says Dr Rodriguez.

The implications of imported ethanol, which may have come from subsidised agriculture or processing plants, have not yet been studied.

Commercial biofuel use in Australia

Many studies and overseas commercial developments demonstrate that a larger biofuel industry could be economically viable in Australia. But according to the Biofuels Association of Australia, investment lags here for a number of reasons.

A prototype woody crop harvester/chipper in action in a mallee plantation in Western Australia. This machine was designed and built by Biosystems Engineering in collaboration with the Future Farm Industries CRC and the Western Australian Department of Environment and Conservation.
A prototype woody crop harvester/chipper in action in a mallee plantation in Western Australia. This machine was designed and built by Biosystems Engineering in collaboration with the Future Farm Industries CRC and the Western Australian Department of Environment and Conservation.
Credit: Richard Sulman, Biosystems Engineering

‘Industry feels that there has been very limited indication from successive governments as to a willingness to support the burgeoning industry,’ says Ms Heather Brodie, CEO of the association.

‘For many years, investment has stalled due to a lack of certainty around the federal government excise regime, and a lack of interest at a state level in mandating the use of the fuels or using other mechanisms to increase their uptake. Indeed, the fuel tax credit regime actually limits the use of biodiesel,’ she says.

However, change is in the air. ‘We have a number of oil majors participating and investing in the alternative fuels space,’ says Ms Brodie. ‘Even over the last 18 months we have seen a substantial shift in attitude with retailers, and I would expect that to increase at a rapid rate.’

Mr Andrew Lang, convenor of The Wood Energy Group and Chairman of the SMARTimbers cooperative, says that while there has been concern about using food-grade feedstock for first-generation biofuel production, countries have increasingly developed cost-competitive technologies for producing second-generation biofuels from wastes and residues.

‘Enerkem in Canada has developed a process to produce methanol and ethanol from gasified biomass wastes, beginning with old, treated power poles,’ says Mr Lang. ‘Their first plant has the capacity to produce five million litres of fuel per year. SunPine in Sweden has commenced production of biodiesel from crude tall oil, a by-product of the pulp and paper industry. Inbicon in Denmark is producing 5.5 million litres of ethanol from fermenting acid-treated straw per year.’

First vs second-generation technology

First-generation tech-nologies are generally already used commercially around the world. These include production of:

  • ethanol from sugar and starch crops by fermentation and distillation

  • biogas, such as methane, from anaerobic digestion of wet wastes

  • biodiesel from waste oils and fats using transesterification.

  • Second-generation technologies are still under development and not yet used widely for commercial biofuel production. They include the use of lignocellulosic plants as feedstock to manufacture ethanol, syngas, synthetic diesel, dimethyl ether and furans, as well as the production of algal lipids to convert to diesel.

    Second-generation technologies have been suggested as the answer to the pressure posed by first-generation technology feedstocks on agricultural land. First-generation feedstocks are generally food crops, such as wheat and corn, which are converted to a liquid fuel. In contrast, second-generation feedstocks include residues from agricultural and forestry production as well as urban organic wastes.

    Worldwide, the assumption that land-use changes associated with second-generation feedstocks will be neutral is being critically assessed. Biofuel users increasingly require assurance that no environmentally detrimental land-use change was associated with the growth or harvest of the biofuel feedstock, such as replacing agricultural land with plantation timber. National and international sustainability criteria are under development, and will include land-use change as an important part of biofuel sustainability assessment.

    Some biofuels are produced in Australia from the conversion of waste oil and tallow (abattoir waste animal fat) to biodiesel. Manildra, the country’s largest ethanol producer, produces biofuel using agricultural by-products. The company uses industrial-grade wheat flour to manufacture protein, using the leftover starch to manufacture ethanol. Ethanol is also made from the fermentation of C-molasses, a low value by-product of the sugar industry in Queensland and northern New South Wales.

    Smorgon Fuels recently announced a venture with Biomax Fuels to produce biodiesel from non?food-grade mustard seed. Smorgon Fuels operates a 100 million-litre biodiesel plant in Victoria that primarily uses oils and animal fats.

    In late 2010, Flex Ethanol Australia was founded by a consortium headed by GM Holden and Caltex to generate ethanol from household rubbish. So far, it has announced a feasibility study trialling Australian-style waste in the ethanol-making process at a Pennsylvanian facility owned by ethanol production specialist, Coskata.

    Qantas has recently announced its support for a feasibility study on building a Fisher–Tropsch plant in Sydney with Solena, a United States fuel technology company. Qantas is a member of the Sustainable Aviation Fuel Users Group, an international collaboration of aviation fuel users, engine manufacturers and fuel manufacturers.


    In gasification, biomass is converted to gas using very high temperatures in a low-oxygen atmosphere. The resulting gas (syngas) can be converted to alcohols such as ethanol for ethanol?based fuels, or alkanes (synfuels or syndiesel) chemically similar to current petroleum-based transport fuels. The Fischer–Tropsch method is used for the latter: a series of chemical reactions to produce a diesel substitute.

    Where the feedstock is woody biomass, gasification has an advantage over hydrolysis because gasification converts all the carbon compounds to syngas, including lignin, which is a serious impediment in the hydrolysis process. Depending on the pathway, the Fischer–Tropsch process does not convert all the gas to liquid and the uncoverted non-liquid portion can be used for cogeneration of electricity to power the gasification plant and export renewable electricity to the grid.

    Existing commercial biomass gasification projects are producing heat and electricity rather than transport fuels. Existing fuel-producing plants use natural gas or coal as feedstock, rather than biomass: it is much easier to move natural gas and feed it on a continuous basis to a gasifier than to handle biomass as feedstock, particularly woody (lignocellulosic) biomass.


    Pyrolysis is the heating of lignocellulose to 450–500°C in the absence of oxygen. The feedstock cannot burn without oxygen and instead is broken down to produce a pyrolysis oil, a char (the solid material that remains after light gases have been driven out or released from the feedstock during the pyrolysis), and a combustible gas mixture. The gas can be used for cogeneration, helping to generate heat for the pyrolysis process or electricity. The char can be used as a ‘biochar’ fertiliser, for renewable energy or to reduce greenhouse gas emissions from the metallurgical industries.

    Several overseas companies produce a stable pyrolysis oil, suitable for use in boilers or even for the production of electricity in a gas turbine. One such company is Canada’s Dynamotive Energy Systems, which also produces biochar. More recently, an upgraded pyrolysis oil has been developed that could act as a ‘drop in’ fuel for blending with, or replacing, diesel, petrol and jet fuel.

    Pyrolysis oil can also be gasified in a similar manner to the raw biomass to produce a syngas for further processing. However, this adds a production step, thereby increasing the cost.

    Hydrolysis (bioconversion)

    Hydrolysis is the breaking up of the cellulose and hemicellulose components of lignocellulosic biomass into individual sugars. The sugars are converted into ethanol by microorganisms in the process of fermentation. Bioconversion encompasses both hydrolysis of the cellulosic components of lignocellulose to sugars and the fermentation of the sugars to ethanol or butanol.

    The hydrolysis of cellulose and hemicellulose to sugars can be achieved by chemical means, using dilute or concentrated acid, or by biological means, using a mixture of enzymes known collectively as cellulases.
    A by-product of the process is lignin, which can be used for cogeneration, via combustion, to produce power to help run the process.

    ‘Cellulases are naturally occurring enzymes that have evolved in organisms such as wood rot fungi and the protozoa found in the guts of termites,’ says Dr Victoria Haritos from the CSIRO’s Energy Transformed Flagship. ‘We have unearthed several new cellulase enzymes from novel Australian organisms that show some promise for increased efficiency of conversion.’

    How much biofuel could Australia produce?

    Another recent study conducted by CSIRO’s Energy Transformed flagship aims to find out how much biofuel Australia could produce. Project leader, Dr Deborah O’Connell, says that a biofuel’s sustainability may vary depending on its type and how much feedstock is used, the technology for conversion of the feedstock and its region of origin.

    The project team first uses data and models to assess the biomass produced in Australia. Then, they apply a series of constraints to the data to make assumptions about the fraction of biomass that would be available for a second-generation biofuel industry. The constraints assess the technical, environmental and economic feasibility of each biomass type. By removing variability from the results, the available amount of biomass is also reduced in each scenario. This gives greater confidence in the results, reducing risk to biofuel industry investors.

    ‘We have identified that we have significant biomass for current production in Australia, and that we could produce more in a way sympathetic to current land use,’ says Dr O’Connell. ‘Analysis done by CSIRO shows that through both modified use of current sources of biomass and use of new sources of biomass over the next 20 years, the biofuels industry in Australia could be scaled up.’

    The Future Farm Industries Cooperative Research Centre (CRC) is researching the potential for new sources of biomass grown in harmony with existing farming. The CRC is leading work on the growth and harvesting of mallee eucalypt trees, which are grown by more than 1000 Western Australian farmers on part of their farms for environmental benefits. The trees coppice (resprout) and could be harvested regularly to provide a sustainable source of biomass to biofuel plants. In a few years, farmers across Australia may be in a win–win situation, planting trees for both environmental and commercial benefits alongside their cereal and livestock operations.

    Dr Joely Taylor works in the Sustainable Biomass Production Project in CSIRO’s Ecosystem Sciences Division. Colin Stucley, who helped write and research this story, is Managing Director of Renewable Oil Corporation and a member of the management committee for Bioenergy Australia, the country’s peak national body for bioenergy research, development and implementation.

    More information

    Farine DR et al. An assessment of biomass for bioelectricity and biofuel and for greenhouse gas emission reduction in Australia. Global Change Biology (submitted).

    Fritsche UR and Wiegmann K (2011). Indirect land use change and biofuels. European Parliament, Brussels.

    Rodriguez L et al (2011). Biofuel excision and the viability of ethanol production in the Green Triangle, Australia. Energy Policy, 39, 1451.

    Stucley CR et al (2004). Biomass energy production in Australia. Rural Industries Research and Development Corporation (RIRDC) Publication No. 04/031. RIRDC, Canberra.

    Warden AC and Haritos VS (2008). Future biofuels for Australia: issues and opportunities for conversion of second-generation lignocellulosics. RIRDC Publication No 08/117. RIRDC, Canberra.

    1 Lignocellulose is comprised of three main components: cellulose, hemicellulose and lignin. Cellulose is made of chains of glucose, a six-carbon sugar, that are tightly bound together as fibres (fibrils). Hemicellulose, composed primarily of five-carbon sugars, surrounds the fibrils of cellulose. Lignin is a complex material built from aromatic organic molecules. It binds or cements the cellulose fibrils together, forming a protective sheath around them.

    Published: 4 May 2011

    Towards baseload solar thermal power

    James Porteous

    Spain’s latest large-scale commercial concentrating solar thermal plants have advanced the generation of solar energy around the clock by using thermal storage. Meanwhile, research continues on the role that concentrating solar thermal plants can play as baseload power support technology under different scenarios.

    The new solar tower at CSIRO’s National Solar Energy Centre, Newcastle.
    The new solar tower at CSIRO’s National Solar Energy Centre, Newcastle.
    Credit: CSIRO

    Traditionally, solar energy generation has only occurred when the sun shines, so it is often said that solar plants can’t ‘do baseload’ – that is, they can’t reliably produce 24-h electricity required to power society. But there is growing global interest and investment in new concentrating solar thermal (known as CST but sometimes called CSP for Concentrating Solar Power) power plants that can store energy and generate mains power, even when the sun is not shining.

    CST technology

    Broadly speaking, the various industrial CST energy generators in operation are made up of different arrangements of mirrors and heat ‘receivers’: troughs, power towers, linear Fresnel and dishes (the different designs are described below). All commercial large-scale solar thermal plants currently heat oil, molten salt or water to generate steam. The steam powers a turbine, which in turn spins an electric generator to create AC (alternative current) power. From the point at which the steam is generated, a CST plant is identical to a coal, gas or nuclear plant in its operating principal. CST solar plants are distinguished by how that steam is generated in the first place.

    The latest generation CST plants use molten salt energy storage and can maintain full turbine output for between 7.5 and 15 h straight, without any sunlight at all. While the use of molten salt storage as a ‘battery’ is not an entirely new concept, it is the demonstration at scale that is of interest. It overcomes variable electricity supply, a key barrier facing other renewable energy technologies.

    The big advance with heat storage

    In November 2008 Spain’s 50 megawatt (MW) Andasol 1 CST plant started feeding power to the grid near Granada in the country’s south, supplying power around the clock using an advanced system of heat storage in tanks of molten salt. Andasol is a trough plant; when its mirrors are collecting sunlight, it heats a synthetic oil that is passed through a heat exchanger to re-heat the ‘cold’ salt before being pumped back into the hot tank. When electrical generation is required, the liquid salt is pumped through a heat exchanger: the heat is transferred to water, which becomes steam that drives a conventional rankine-cycle steam turbine (Siemens SST-700 turbines), and then returned to the ‘cold’ tank.

    The adjacent Andasol 2 plant was completed soon after, and as of March 2011 Spain had 11 CST plants, for a total of 765 Mwe of solar thermal in operation, more than half of which has molten salt storage. Planned solar thermal capacity is expected to push the total to 2500 MW by 2013, with the Spanish sector standing to exceed 10 000 MW by 2020.1 These CST plants are rated with 7.5 h of thermal storage each, however, operators can produce electricity over longer periods by running at lower output, giving the plant round-the-clock generating potential.

    The completed Gemasolar Solar Tres plant with adjoining salt storage tanks <i>in situ</i> beside the tower.
    The completed Gemasolar Solar Tres plant with adjoining salt storage tanks in situ beside the tower.
    Credit: Torresol Energy

    ‘Power towers’ and storage

    Attention is now focused on the recently completed Gemasolar (pronounced ‘hemasolar’) Solar Tres project near Seville, also in the south. Solar Tres is the first commercial CST plant of ‘power tower’ design to have salt storage – some 15 h worth. The tower configuration allows the plant to achieve higher operating heat and efficiencies. The salt will be heated to ~565°C, meaning greater energy storage and greater thermal efficiency than for a trough plant. At these temperatures, each megawatt hour (MWh) of energy generated requires ~25 tonnes of salt. Plants operating at lower temperatures require proportionally more salt per unit of energy stored. Trough plants have an upper temperature of 400°C and store energy at the ratio of 1 MWh per 75 tonnes of salt.

    Changing the relative sizing of the mirrors, storage and turbine in plants allows for a different balance between maximum power and energy storage. In the case of Solar Tres, the sizing choices mean 15 h of storage at full power, giving true baseload capacity. These levels of average utilisation (~75 per cent) compare favourably with Australian base-load coal-fired power plants (on average NSW coal plants operate at an average 63 per cent of rated capacity).

    Solar thermal in the US

    While Spain leads with the first commercial CST-towers-with-storage plants, the US Bureau of Land Management (BLM) has received 148 applications for solar developments (97 000 MW potential) on public land. Many of these applications are for superior tower-type systems using molten salt for 24-h supply. Fred Morse, head of the Solar Energy Industries Association, and Thomas Mancini, head of Sandia National Laboratories, expect up to a dozen large-scale commercial solar thermal plants to break ground this year.

    Costs of the technology

    The US, first-of-kind medium-scale (75–150 MW) solar plants with thermal storage can generate power at about AU$0.25/kWh. New technologies always follow a cost reduction curve once they mature and economies of scale are realised. Research by Melbourne’s Energy Research Institute2 suggests that CST could hit parity with new coal and gas plants once global installations are in the order of 10 000 MW, which even under business-as-usual growth could occur by 2020 or earlier with the combined growth in existing markets of southern Europe, North Africa and the United States. Companies Torresol Energy from Spain, and Solar Reserve from the USA, now provide commercially available solar power systems (with storage) with operating characteristics comparable to a conventional coal, nuclear or gas combined cycle plant.

    In its recent report ‘Zero Carbon Australia – Stationary Energy Plan’3, Beyond Zero Emissions (BZE) posits that Australia’s entire energy needs could be met with a 60:40 mix of Spanish-style solar thermal, and wind. Technologies like geothermal and wave power show promise, but solar thermal and wind can be deployed at scale today and are sufficient to entirely power the country. But, while BZE support the potential of CST with thermal storage to contribute to energy supply in Australia, they believe that policy and financial frameworks are required for commercial maturity and wider application.

    Australia and CST

    Australia’s interest in the potential of CST has been led by CSIRO for more than a decade. Research is focused on finding pathways to least-cost but highest thermal-efficiency solar collectors and ‘receivers.’ There is now also concerted exploration underway into next-generation high temperature thermal and battery storage, which at 1400°C could achieve 50 per cent more electricity from the same collection area.

    Dr Jim Smitham, Deputy Chief at CSIRO’s Energy Technology Centre in Newcastle, says while the Spanish and US CST thermal storage plants are important demonstrations of the technology’s potential, large-scale, in Australia, CST hasn’t proven itself enough commercially as standalone technology – compared to, say, wind power. It still needs to secure financiers’ confidence that here it can be a profitable, responsive supply to meet the fluctuating daily demand pricing (serving shoulder price and peak price periods is particularly important). ‘That’s why CSIRO is looking at a transition pathways role for CST technology that assists already commercially endorsed fossil fuel generation to shift to lower carbon operation.

    ‘As well as investigating stand-alone CST, we are investigating hybrid solar/fossil fuel and solar/geothermal plant combinations, including solar-assisted gas turbine or high-temperature steam support for fossil fuel power stations to achieve greater thermal efficiency at lower cost.

    Dr Smitham also says ‘Molten salt is not the last word in CST power storage. We still need very high temperature, low-cost storage to be available at different scales. Over the last 18 months, CSIRO has started looking at the leading edge in least-cost, higher temperature storage beyond molten salt.’

    More information

    Previous Ecos articles: and
    CSIRO’s solar webpages:
    Information about Solar Tres:

    More on the different CST technologies

    Trough plants

    Trough technology is the most proven CST design. The largest solar generation facility in the world, called Solar Energy Generating Systems (SEGS) in California, uses troughs. SEGS is a set of nine plants near Kramer Junction in the Mojave Desert. Jointly they have a capacity of 354MW.

    In a trough configuration, long lines of horizontal, parabolic mirrors focus solar radiation on a pipe through which a fluid is pumped and heated to a maximum of around 400°C. The fluid is usually a high-grade synthetic oil which does not boil or degrade at high temperatures.

    In a trough plant, the mirrors rotate around their long (North–south) axis to follow the Sun during the day. Because they remain horizontal, and so don't track the Sun's elevation, trough mirrors are most effective close to the Equator where they don’t suffer reduced solar efficiency – called the projection effect’ – from this inability to follow the sun’s elevation. At the latitudes of southern Australia, trough mirrors are only about half as effective as a mirror that can more closely track the sun.

    Trough mirrors from a Spanish solar power plant.
    Trough mirrors from a Spanish solar power plant.
    Credit: BZE

    Linear Fresnel plants

    The curved mirror structures of a trough plant are very expensive. A less-expensive variant on the trough mirror configuration is a Linear Fresnel (pronounced 'frenell'). which uses long, near-flat mirrors close to the ground to make an optical approximation of a parabolic trough, without the structural complexity.

    These systems, such as those from Biotec Novasol (owned by Australian company Transfield) and Areva Solar (formerly Australian company Ausra), have relatively low operating temperatures of around 290°C. Therefore, no commercially viable energy storage is available because not enough heat is generated to liquify storage salt. However, Linear Fresnel companies are moving to higher temperatures and pressures, such as Mann Ferrestel / Solar Power Group who are offering a 450°C operating temperature, meaning more viable efficiency for thermal storage.

    A Linear Fresnel assembly.
    A Linear Fresnel assembly.
    Credit: Areva Solar

    Dish plants

    Mirrors in a dish configuration are effective at concentrating the solar rays and track the sun in two axes. They can achieve temperatures as high as 2000°C (but are typically run at between 500°C and 650°C for electricity generation). Historically they've been expensive and not often used in solar energy plants. Australia's first solar thermal power plant was a 25kW dish-based facility developed by The ANU at White Cliffs in NSW which operated from 1981 to 1996 for an off-grid community.

    The ANU has since developed the world's biggest mass production solar dish system - the ANU SG4, fourth-generation dish - which is now ready for mass production. To save costs, it is built in the field on a very accurate jig, instead of adjusting the dish after it has been manufactured.

    An SG4 dish mirror from ANU in Canberra.
    An SG4 dish mirror from ANU in Canberra.
    Credit: BZE

    Tower plants

    Tower-based systems use a large field of near-flat, independently controlled mirrors called heliostats to focus light on a central receiver at the top of a tower. Heliostats are spaced to ensure they don't overshadow each other. Tower configurations can scale up to involve many hundreds, or thousands, of mirrors. This gives towers the greatest capacity to concentrate the sun's rays, leading to higher operating temperatures.

    A modern tower-based solar plant would typically pass a fluid through the ‘receiver’ to be heated up to ~570°C (and in future up to ~650°C). At this temperature, electrical generation can be more efficient and cheaper than that from a trough configuration which heats to ~400°C.

    The turbines required in conjunction with a tower are the same as those used in coal-fired plants, whereas the turbine technology required for lower-temperature operation is considerably more expensive because of the much lower economies of scale.

    Spain’s PS10 power tower near Seville.
    Spain’s PS10 power tower near Seville.
    Credit: BZE

    Capturing the sun efficiently – the projection effect

    Heliostat mirrors track the sun in two axes which makes them more efficient than horizontal trough mirrors, especially in winter and when sited further from the Equator. Compared with a dish, which gives the best sun tracking, a trough mirror captures ~75 per cent less energy in winter at temperate latitudes because of the low angle of the Sun. This reduction of collection capacity is called the projection effect.

    Solar engineers use the term insolation to describe the measurement of received solar energy, and Direct Normal Incidence (DNI) to describe the solar energy available to collectors which track the sun, i.e. no projection effect. For horizontally configured mirrors, the insolation is less (due to the projection effect) and measured as Global Horizontal Irradiance (GHI).

    The projection effect comparing vertical sun's rays with rays at 30 degrees.
    Credit: BZE

    The solar resource

    It is often highlighted that Australia’s solar resource greatly exceeds our energy needs. At ground level, the power of the Sun on a one meter square surface, at right angles to the Sun's rays, is ~1 kW (kW).

    Excluding cloud effects, this gives an average of ~6 kW-hours (kWh) per day for every square meter collecting sunlight. Across a sunny country as large as Australia, this represents a phenomenally large resource.

    Solar energy equivalent to Australia's total current electrical peak generation capacity (~49GW4) falls as sunlight on a square area ~8km by 8km (at noon at southern Australian latitudes), or ~0.001 per cent of Australia’s landmass.

    When you take into account typical sunlight patterns, and typical plant efficiency and layout, you still need less than 0.05 per cent of Australia's area to generate equivalent power. To put the required land area in perspective, it would fit six times in Anna Creek, Australia's largest cattle station.

    Text explaining the different CST technologies provided by Beyond Zero Emissions (BZE).

    2 Hearps, P and McConnell, D (2011), Renewable Energy Technology Cost Review, University of Melbourne Energy Research Institute, Melbourne,
    3 Full report:
    4 According to ABARE 2010

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