Renewable energy technologies update

30 November 2009

Stewart Needham

Science, Technology, Environment and Resources Section

Contents

Introduction
Solar Thermal Energy
Solar hot water
Solar chimneys
Solar ponds
Parabolic troughs and dishes and Fresnel collectors
Solar towers
Solar Photovoltaics
Geothermal energy
Hot fractured rock
Geothermal aquifer
Wind energy
Ocean energy
Tidal power
Wave energy
Marine currents
Thermal layering
Salt gradients
Hydro power
Bioenergy
Energy storage and continuous supply technologies
Battery systems
Hydrogen
Thermal systems
Conclusion
Appendices
Operating and planned renewable energy technology installations in Australia
The largest operating installations for each renewable energy technology in Australia
Examples of some large proposed renewable energy technology projects
The cost of electricity production from renewable energy technologies

Introduction

The transition to a carbon–constrained economy is likely to have major social, economic and technological impacts. A key part of this transition will be the development, commercialisation and large–scale deployment of renewable energy. This will be highly dependent on political and economic drivers, but effective exploitation of renewable energy will firstly rely on the development of suitable technologies. It is the technological perspective that is explored in this paper.

There are many different forms of renewable energy sources and technologies, and it is likely that scientific research will develop as yet unknown ways in which energy can be tapped from renewable sources. This background note reviews renewable energy technologies as they exist today, covering solar thermal, solar photovoltaic, geothermal, wind, ocean, hydro, bioenergy, and energy storage technologies in turn. Examples of Australian projects and innovations are provided where appropriate. Lists of renewable energy installations in Australia, examples of large proposed projects, and the cost of electricity generated by the various technologies, are provided in the Appendix.

Solar Thermal Energy

Solar thermal technologies (STT) concentrate solar radiation on to a receiver, where it is converted into heat, which can then be used directly or to boil a liquid to produce steam to drive turbines. STT is suitable for large–scale electricity generation and there are a number of technology options available, although they are at different stages of development and deployment.

Solar thermal energy is emerging as a cost–competitive source of electrical power, especially because it can be easily integrated with current conventional energy sources such as coal power generation.[1] The International Energy Agency (IEA) currently estimates that solar thermal energy will become cost–competitive with conventional hydrocarbon energy sources by about 2030.[2] Current costs of solar thermal systems are the lowest of any solar technology, but more expensive than hydro, wind and biomass.

STT can be split into two groups:

  • zero to low concentration, low temperature solar thermal technologies, including solar chimneys, solar ponds and solar water heaters, and
  • high concentration, high temperature solar thermal technologies, such as parabolic troughs and dishes and Fresnel collectors, and multi–tower solar arrays with a central receiver (‘solar towers’).

Types of technologies under these groups are discussed in more detail below.

Solar hot water

Heat–absorbing flat panels or vacuum tubes capture solar radiation and transfer the heat by circulating water to a storage tank. The water may flow through the panel or may collect heat via a manifold at the top of the tubes or panel array. A small pump activated by a differential heat sensor is used to circulate the water. The systems are mostly used for domestic and small–scale industrial applications, with fixed collectors mounted on the roof, sometimes on frames to place the collector perpendicular to the incidence angle of winter midday sunlight for maximum efficiency. These small systems are not applicable to electricity generation, but reduce electricity demand.

An evacuated tube system

An evacuated tube system.

Reproduced with permission, Aussie Solar.

In evacuated tube installations, metal–oxide coated glass tubes concentrate the sun’s heat which turns water into steam within a small sealed copper tube running up the centre of a larger, partially evacuated glass tube. At the top of the array these fine tubes protrude into a heat exchanger where heat is transferred to water being circulated by a small pump. This water then flows to a hot water storage tank.

Flat panel system with floor mounted storage tank and gas booster.

Flat panel system with floor–mounted storage tank and gas booster.

Reproduced with permission, All Solar Systems Pty Ltd www.allsolarsystems.com.au

Flat panel systems are less efficient in capturing the sun’s heat than the evacuated tubes. The sun heats water inside black, commonly finned tubes, under a glass panel. There are two types of installation: close–coupled systems, where the hot water storage tank is immediately above the panels so that no circulating pump is required (as warmer water rises inside the panels into the storage tank, it displaces cooler water which recirculates through the panel); and split systems, where a small pump circulates water between the panels and a storage tank inside the house or at ground level.

Solar chimneys

Solar chimney technology harnesses energy from hot air. They are also sometimes called solar towers, but the energy harnessing mechanism differs from solar towers that use mirrors to concentrate sunlight onto a central collector tower (see below). Solar radiation heats air under a large translucent canopy; the heated air rises rapidly to flow through turbines positioned near the base of a very tall hollow structure at the centre of the canopy—the chimney effect causes a continuous thermal updraft to drive turbines to generate electricity. This electricity generation method does not use any water.[3]

Australian company EnviroMission Ltd has entered into an agreement with the Southern California Public Power Authority to negotiate power purchase arrangements which if successful would facilitate construction of two 200 MW solar chimneys in the USA. (EnviroMission Company Announcement: EnviroMission Solar Tower wins SCPPA approval, 27 October 2009).

Conceptual graphic reproduced with permission from Enviromission Ltd

Solar ponds

In solar pond systems, solar radiation enters a body of saline water several metres deep with increasing salinity with depth, where heat up to 80°C is stored in the lower layer. Low–grade heat (40–80°C) is available on a 24 hour basis for heating applications.

Trial solar pond developed by RMIT Melbourne.

Trial solar pond developed by RMIT Melbourne.

Reproduced with permission RMIT Sustainable Energy Program

The energy from a solar pond is suitable for low–temperature applications such as space-heating or water-heating for agriculture, aquaculture, water desalination and salt production. There is potential for electricity generation using Stirling engine technology[4], but it is not suited to electricity generation using conventional technologies.

Parabolic troughs and dishes and Fresnel collectors

Parabolic troughs are long parabolic mirrors which concentrate and reflect sunlight onto a horizontal tube. Fluid running through the tube picks up heat and is used to heat steam in a standard turbine generator. The mirrors can be rotated to track the sun on a daily or seasonal basis. Thermal efficiency for heating the fluid ranges from 60–80 per cent. Overall efficiency from collector to grid is about 15 per cent, similar to photovoltaic cells.  The world’s largest solar power electrical generators presently use parabolic trough arrays. A variety of approaches are used to harvest the heat at the focal point of the reflectors, including water and oil–filled pipes, direct steam generation, and evacuated tubes similar to those described in solar hot water systems.

The largest parabolic trough generation plant is installed in Southern California

The largest parabolic trough generation plant is installed in Southern California and has been supplying power to the grid since the 1980s. The plant was installed in stages and has a total capacity of 354 Megawatts (MW)[5], with over 200 hectares of trough concentrators. Other large–scale solar thermal plants are under construction or proposed in Europe and the United States. Pictured is part of an experimental parabolic trough array at the National Solar Energy Centre at CSIRO Energy Technology in Newcastle.

Photo courtesy of CSIRO

A parabolic dish is a large concave curved mirror which concentrates sunlight onto a focal point where the temperature may reach up to 3000oC. This heat can be used to generate electricity or make hydrogen fuel. A receiver positioned at the focal point above the dish captures the heat and transforms it into energy, commonly using a Stirling engine or a steam engine to create rotational energy to drive an electric generator.

A parabolic dish

CSIRO has successfully demonstrated a process of reforming natural gas to hydrogen using a 107 m3 solar dish concentrator at its Lucas Heights facility, Sydney.

Photo courtesy of CSIRO

A Fresnel collector is a series of long, narrow, shallow–curvature or flat mirrors that focuses light onto one or more linear receivers positioned above the mirrors. On top of the receiver a small parabolic mirror can be attached for further focusing the light. Cost is lower than trough and dish concepts because a receiver is shared between several mirrors; there is just one axis for tracking; and as the receiver is stationary, fluid couplings are not required. The mirrors also do not need to support the receiver, so they are structurally simpler.

A Fresnel collector

A bank of Fresnel reflectors focussing sunlight on to a collector pipe in which heated fluid flows to a generating turbine.

Photo source: Ausra Inc., reproduced under GNU Free Documentation Licence

Solar towers

Solar tower systems consist of an array of flat, movable mirrors (heliostats) that focus sunlight upon a collector tower, in which a substance is heated. Water was originally used for immediate power generation via a steam turbine, which did not allow for power generation when the sun was not shining. Other media can be used to store heat from which steam can be generated to run turbines at any time of day: purified graphite is being used in the 10 MW power plant in Cloncurry; liquid sodium (sodium is a metal with a high heat capacity) has also been successfully demonstrated as a heat storage medium.

A variation on the single tower is the multi–tower solar array, where several tower–mounted receivers stand close together so that the surrounding heliostat fields partly overlap. In some parts of the total heliostat field the mirrors are alternately directed to different aiming points on different towers, so that radiation is collected which would usually remain unused by a conventional solar tower system due to mutual blocking of the heliostats.

 

multi–tower solar array

This experimental high concentration tower solar array at the National Solar Energy Centre in Newcastle NSW uses 200 mirrors to generate more than 500 kilowatts (kW) of energy. It can achieve peak temperatures of over 1000°C. Much larger arrays are already operating commercially in California USA.

Photo courtesy CSIRO

The high up–front cost of equipment to collect and store solar energy, the large collecting areas, and intermittence, act to reduce the rate of uptake of the high concentration/high temperature Solar Thermal Technologies. However, their capacity to generate hydrogen as a method for storing energy and moderating intermittency of electricity, as well as providing hydrogen for use beyond the stationary electricity sector, suggest that these STTs will make a significant contribution in the future renewable energy mix.

Solar Photovoltaics

Photovoltaic (PV) technology transforms the energy of sunlight (solar photons) into direct electric current using semiconductor materials. The basic unit of this technology is a PV or solar cell. When photons enter the PV cell, electrons in the semiconductor material are freed, generating direct electric current. Solar cells are made from a variety of materials and come in different designs. The most important PV cells are crystalline silicon and thin films, including amorphous silicon.[6]

A typical roof–top domestic PV panel installation

A typical roof–top domestic PV panel installation, with a solar hot water panel behind.

Reproduced with permission from www.SolarGuys.com.au

The amount of energy that can be produced is directly dependent on the intensity of available sunshine and the angle at which solar PV cells are oriented. PV cells are still capable of producing electricity even in temperate winter conditions and during cloudy weather, albeit at a reduced rate (high summer temperatures also reduce the efficiency of the photoelectric effect to some degree). Obviously, however, the cells will not work at night. Most current photovoltaic power is decentralised, being generated on rooftops to power individual buildings.

PV is reliable and low maintenance, and readily adaptable and scaleable from stand–alone (off–grid) systems where back–up is generally required commonly in the form of a diesel generator, to grid–connected systems where excess electricity production can be sold into the grid and there is no requirement for storage or back–up systems, to utility–scale systems that constitute a primary electricity source for distributed use.

There is considerable commercial potential for larger–scale PV array systems, provided capital cost can be brought down, for example through thin–film technology such as ‘SLIVER technology’, where the amount of silicon required is substantially reduced.[7] In California, 250 MW of PV panels are being installed on 600 hectares of industrial roof space, in a $1 billion initiative announced in March 2008. Technologies are under development to better integrate PV into building architecture, including modular rooftop PV systems, the development of a solar PV rooftop tile, and solar PV wall panels.[8]

PV array systems

PV can also be integrated with other solar energy technologies to improve efficiency in energy production: a grid–connected 154 MW Heliostat Concentrator Photo Voltaics plant (HCPV) due to be commissioned in Victoria in 2013 will use heliostats (mirrors) to concentrate solar radiation by a factor of 500, onto high–efficiency PV cells developed by Boeing for satellite energy systems. The output is 1500 times the power output of the same area of a conventional PV cell. The cost of power generated is expected to be three–quarters of that from traditional PV technology.[9]

Reproduced with permission: Solar Systems Pty Ltd

Geothermal energy

Geothermal energy involves tapping heat within the Earth’s crust. This has been achieved for many years in volcanically active countries like New Zealand and Iceland, but apart from a few small sources of hot bore water, geothermal energy has not been utilised in Australia due to lack of natural active geothermal outlets. However, Australia has substantial potential sources for energy in the form of ‘hot fractured rocks’ (HFR).

Hot fractured rock

In some parts of Australia rocks occur within five kilometres below the surface at temperatures of 250°C and higher. This represents an enormous energy resource which can be tapped by pumping water into the hot rocks and extracting it as high pressure steam to run conventional steam turbine power equipment. Preliminary work by Geoscience Australia suggests a potential HFR resource equivalent to 26 000 years of Australia’s energy use at 2005 levels.[10] 

To develop this resource, boreholes need to be drilled into the hot rocks to facilitate the injection of water, which passes through fractures in the rock to extraction boreholes and returns to the surface as steam.  Success primarily depends on the ability to drill deep into hot hard rock, and the existence of fractures that allow the water to pass through to the extraction bores.

Hot fractured rock technology

Hot fractured rock technology is at the experimental stage with no commercial schemes anywhere in the world. Successful development of the main areas in remote Queensland and the eastern parts of South Australia will require large–scale engineering and major infrastructure development to link it to the grid. There is also some potential in the Hunter Valley which is well located to tap into the existing electricity grid.

Original image courtesy of Geodynamics Limited

Geothermal aquifer

Australia has very limited geothermal aquifer resources—unlike the volcanically active regions of New Zealand. Australia’s best resources are in the Great Artesian Basin region, where many bores discharge water at high enough temperatures to operate heat engines. Two small–scale power plants utilise low temperature hot water to generate electricity for remote settlements, and a small geothermal power station is operating as a demonstration in Birdsville. As the resource is available only in central Australia and is limited in capacity, it can only supply the very few towns located nearby.

Wind energy

Wind turbines operate on a simple principle that is effectively the opposite of an electric fan. The energy in the wind turns two or three propeller–like blades around a rotor, whose shaft spins a generator to create electricity. The turbines are mounted on a tower to capture the most energy. At 30 meters or more above ground, they can take advantage of faster and less turbulent wind.

Modern wind turbines fall into two basic groups: the more common horizontal–axis ‘fan’ variety, such as those recently constructed on the eastern shores of Lake George north of Canberra, and the vertical–axis design, ‘eggbeater’ Darrieus model. The vertical axis design can be ground–mounted and thus cheaper to install, but at ground level much less wind energy is available; and the uneven distribution of torque generated by the blades creates stresses which need to be contained by limiting the rotational speed. At present, there are no vertical axis wind turbines in the megawatt class and so their potential contribution to grid electricity generation appears very limited. However, the vertical axis design can be easily deployed on building–tops (as can small horizontal axis turbines) and may be increasingly integrated into sustainable building designs.

Single small turbines below 1000 kW capacity are used for homes, telecommunications dishes, or water pumping. Small turbines are sometimes used in connection with diesel generators, batteries, and photovoltaic systems. These systems are called hybrid wind systems and are typically used in remote, off–grid locations, where a connection to the utility grid is not available. Utility–scale turbines range in size from 1000 kW to as large as several megawatts. A variation on the smaller turbines is the recent development of shrouded rooftop turbines aimed at commercial urban sites. The shroud increases wind speed through the fan so that more energy can be produced from a smaller turbine, and energy can be generated from wind speeds as low as eight kilometres per hour.

The ‘WindCube’

The ‘WindCube’ is a 7 m2 shrouded turbine rated at
60 kW which can be roof or tower–mounted.

© Green Energy Technologies . Reproduced with permission from Get Smart Energy Inc

Larger turbines are grouped together into wind farms, which provide bulk power to the electrical grid. The largest installations have towers over 130 metres high with a blade diameter up to 126 metres, and a generation capacity of 7 MW.[11] The trend towards larger rotors and taller towers is expected to continue, further improving performance and reducing the unit cost of electricity, which has been reduced by 50 per cent in the past 15 years.

The 140 MW Woolnorth wind farm in NE Tasmania

The 140 MW Woolnorth wind farm in NE Tasmania is currently Australia’s largest fully operational wind power site, with 62 turbines producing enough electricity for around 70 000 homes.

Graphic courtesy of Roaring 40s

Ocean energy

Energy can be tapped from the oceans in several ways, from tides, waves, marine currents, thermal layering, and salt gradients. There are tide and wave installations in several countries, and there is significant research and pre–commercial development taking place into a range of technologies suited to large–scale applications. Tidal and wave energy projects are in development in Australia.

Tidal power

Tidal power can be generated either from the energy contained in the water due to the difference in height between low and high tide, or from the energy of strong tidal currents that occur in narrow passages as the tide rises and falls, or from a combination of both. A high tidal height will generate large currents, but relatively strong currents can also occur with small tidal heights as a result of channel and bay shape.

Tidal power incurs relatively high capital costs, and construction times can be several years for larger projects. In addition, operation is intermittent with a relatively low load factor (22–35 per cent).[12] Thus, although plant life can be very long, the high capital costs and long construction time have deterred the construction of large tidal schemes.

A tidal range of at least five metres is considered necessary for large–scale installations. Australia’s best tidal energy resources are in the Kimberley region, which experiences one of the largest tidal ranges in the world. However, given the high costs of transmitting the power to far–away metropolitan regions, the resource may only be suitable for local demand. Tidal energy was considered for the Derby region of WA in 2001, but a gas–fired power station was chosen on economic and environmental grounds.[13]

Sydney–based BioPower Systems is developing a system to harness the power in tidal currents.[14] The company has signed a Memorandum of Understanding with Hydro Tasmania to test and demonstrate the system off Flinders Island, and intends to commence commercial production in 2010.[15]

Wave energy

Wave energy systems do not make use of waves as such, but rather the swell that occurs in deeper water, which may be captured by coastal installations. Australia has potentially large wave resources located close to land, particularly along the southern coastlines. Four types of technology are being used or trialled at commercial scales:

  • point absorbers such as fixed buoys where the reciprocating up–down movement powers pumps which pressurise sea water, or surface floats where connecting rods turn a horizontal shaft which directly powers the generator
  • attenuators which are like hinged rafts with movement of the hinges pressurising sea water
  • overtopping, where wave water spills over into an impoundment and the water drains out through turbines under gravity, and
  • terminator systems, where wave oscillation confines air in a closed chamber and this pressurised air drives a turbine (also called oscillating water column (OWC) devices).

Four different systems are being trialled in Australia. Some installations have the capacity to pump water under sufficient pressure for production of fresh water in desalinisation plants through reverse osmosis in addition to or instead of producing electricity.

The CETO system in Fremantle

The CETO system in Fremantle, based on point absorber technology, utilises the motion of underwater balloons to pump seawater ashore under pressure to produce electricity via a turbine, or for desalination via reverse osmosis. The system is modular, with each balloon capable of generating 180 kW. A ‘wave farm’ of 300 units with 50 MW capacity would cover the area of two football fields and produce an average of 20 MW. Demonstration trials of the same technology that could lead to 50 MW installations are at the planning stage for Elliston and Point MacDonnell in South Australia.

Reproduced with permission, Carnegie Corporation Australia, http://www.carnegiecorp.com.au/

OceanLinx  

OceanLinx is a moored OWC type in which wave energy is focussed in a confined chamber by a parabolic wall; the resulting compressed airflow passes through a turbine to create electricity. A prototype 450 kW unit has been installed at Port Kembla and a power purchase agreement has been signed. Another project is at the permitting stage at Portland, Victoria. Commercial development of an 80 MW system is anticipated once the reliability of the system is demonstrated. The system requires fairly deep water near the coast and can be integrated into the construction of coastal structures such as harbour breakwaters.

Reproduced with permission,  Oceanlinx Ltd, http://www.oceanlinx.com/

The ‘Waverider’

The ‘Waverider’ is another ‘point absorber’ type which consists of rows of caged buoys with connecting rods to long horizontal shafts which drive generators; all held by a large pontoon. A pilot plant is planned for Wellington Point on the Eyre Peninsula, South Australia.[16]

Reproduced with permission, Wave Rider Energy Pty Ltd

BioPower’s bioWAVE

BioPower’s bioWAVETM ‘point absorber’ is a hinged system designed to mimic the swaying of sea plants. A 250 kW system is to be trialled off King Island, Tasmania, scheduled for operation in 2010.

Reproduced with permission, BioPower Systems, http://www.biopowersystems.com 

Marine currents

Marine currents represent a major potential energy resource, although deep water construction and connection to grid from remote ocean installations may present a significant cost barrier. SEAGEN is a 1000 tonne twin–rotor 1.2 MW device installed just offshore near Belfast in 2008. It is suited to 20–40 metre deep water, and features rotors whose pitch can be varied over 180° to capture energy from ingoing and outgoing currents.

Seagen with twin rotors raised for maintenance

Seagen with twin rotors raised for maintenance

Image available through Creative Commons Licence, GIZMO the gadget blog.

A British company is partnering in Korea to construct an array of 300 rotors, each 20 metres high, which will sit on the sea bed in the nine metre tidal range Wando Hoenggan waterway near the southern tip of the Korean peninsula. This installation is expected to deliver 300 MW when completed in 2015.[17]

Thermal layering

Ocean thermal energy conversion technology is in the development phase. The US government is funding two projects in the Pacific Ocean which could be operational by 2014, in the eight to 20 MW range and producing five Megalitres of desalinated water daily. The temperature difference between warm near–surface and cold deep seawater is used to heat then cool a circulating fluid such as ammonia or a mixture of ammonia and water. First, warm surface water causes the fluid to boil, creating enough gas pressure to drive a turbine that generates power. The gas is then cooled by passing it through cold water pumped up from the ocean depths via pipes in the order of 1000 metres long and several metres across, which suck up cold water at rates perhaps up to 1000 tonnes per second. While the gas condenses back into a liquid that can be used again, the water is returned to the deep ocean. The technology is generally restricted to tropical latitudes between 20°N and 20°S where there is a large thermal gradient between upper and lower waters.

Ocean thermal energy conversion technology

 

 

 

 

Schematic diagram describing the principles by which energy can be generated by harnessing the temperature gradients of the oceans.

Graphic sourced from New Scientist magazine[18]

Salt gradients

There are a number of technologies to exploit salt gradients. Pressure retarded osmosis is presently the most promising one, but others include vapour compression and reversible dialysis. Pressure retarded osmosis is based on establishing a fresh water reservoir and a salt water reservoir at river mouths, where a semi–permeable membrane divides the two reservoirs. The membrane prevents salt water from mixing with fresh water, but lets the fresh water through to the salt water reservoir. The salinity gradient will make the elevation head (height of the water) in the salt water reservoir increase. This elevation head can be exploited by letting out water through a turbine, as a regular hydro power plant.

There are no known commercial installations of this technology, and it appears that semi–permeable membranes with sufficient efficiency, strength and durability to be able to carry out a pilot test have yet to be developed. However, model tests have been conducted that confirm that the theory works in practice.

Hydro power

Hydro power is presently the largest exploited renewable energy source by far (90 per cent of renewable electricity production), providing around 2.2 per cent of the world’s total energy production and 16 per cent of the world’s electricity. Most of the installed capacity is in Europe and the Americas, and the largest potential for expansion is in Africa, Asia and South America. Hydro power production is expected to increase by 1.8 per cent annually until 2030, although its share of energy production will remain unchanged at about two per cent. Environmental issues, coupled with diminishing river flows, suggest little potential for expansion in Australia through construction of new dams. However, there is potential for small–scale expansion based on mini–hydro systems.

Installations can be divided into three types based on the pressure and height characteristics and power output: low–head power stations, high–head power stations and mini–hydro. The first two utilise reservoirs or dams that create a height difference with associated potential energy that can be harnessed when the water is released, while the last relies on in–stream installations that harness energy from the flow of water.

  • Low–head power stations often utilise a large water volume but have a low head (height of fall), as in a run–of–river power station. Since there is little height with which to regulate the flow of water, it is used when available. The amount of electricity generated therefore increases considerably when the river is in high flow. The river is dammed and water fed into one or more turbines. After having been exploited in the turbines, the water runs back into the river below the power station.
  • High–head power stations are generally constructed to utilise a high head but smaller volume of water than run–of–river installations. Many types of these power stations store water in reservoirs which is fed under high pressure through pipes to the turbines. Reservoirs allow a larger proportion of runoff to be used in power production. They usually have a larger installed capacity than run–of–river stations, but a shorter utilisation period. Generating productivity is influenced by the efficiency of turbine design. Optimisation of turbine design to suit differences in head and flow volume is continuing.
  • Mini hydro generation encompasses installations of less that 1 MW which can be inserted into existing pipeline flows and in stream flows. A Victorian government study identified the potential to install 16.5 MW of mini hydro electricity generation on existing water supply infrastructure, and Melbourne Water is currently developing six mini hydro–electricity generating sites on its water supply system.[19] The study also identified the theoretical mini–hydro potential within Victoria's stream network which is greatest in the east and northeast of the state. There is also a mini hydro plant installed in one of South Australia’s mains pipes that diverts water from the Murray River to a storage tank.[20]

Bioenergy

The raw materials for bioenergy are derived from any organic material, including waste products or biomass grown specifically for the purpose (for example wood, oilseed, and algae). Energy can be derived by direct burning, for example wood and bagasse (a by–product of sugar production which has been used in Australia for 50 years to contribute about one per cent of our electricity generation capacity). However, most requires processing to produce a suitable feedstock for power plants, and currently there is rapid technological development in the areas of thermochemical and biochemical processing of bioenergy feedstock materials.

Pathways from biomass to solid, liquid and gaseous energy resources
(source: Renewable Energy 2007, www.reneweableenergy.no )

Commercial bioenergy resources are mainly biomass solids derived from forestry and farming by–products and from urban waste. It is also possible to produce biomass from aquaculture, but this has not been used for energy purposes so far. Wood waste is the largest input globally, although bagasse is the largest input in Australia. Vegetative matter can be grown specifically to be burned directly to produce energy, or to make biofuels, but in many cases this is considered environmentally and economically inefficient as it can lead to deforestation or supplant other, more high–value forms of food agriculture and potentially impact food security.

Biomass as gas entails harvesting methane from the natural breakdown of organic material—principally human or animal sewerage, municipal rubbish, and waste from food processing—or biochemical processing. Most of Australia’s capacity for biogas electricity production in Australia is through burning methane at sewage treatment plants and from landfill gas collected from municipal waste depots. In the future there is potential to generate hydrogen from biomass, to contribute to a hydrogen economy which some believe is the energy base of the future.

A variety of liquid biofuel products are also available, which offer benefits of easy storage, transport and handling compared with the solid and gaseous biofuel options. The liquid fuel also has a higher energy density. Variations include ethanol and methanol which are produced by fermentation of sugars; pyrolysis (decomposition by heating) of vegetable and animal fats or solid biomass to produce biodiesel; and refining of biogas to produce syngas and then liquid fuel.

Energy storage and continuous supply technologies

Scepticism over the ability of renewables to displace significant generating capacity from conventional sources has arisen due to the inherently intermittent nature of wind and solar, and their apparent limited ability to provide continuous power.[21] Contributions to the grid at lower levels of penetration are not an issue: intermittent renewable energy sources are presently connected into the UK power system without significant difficulty and with no requirement for energy storage, and this is expected to extend to beyond 10 per cent of the total electrical energy mix being derived from renewables.[22]

Economic benefits from higher levels of penetration of renewables in the energy sector could be constrained by the volatile nature of primary supply availability, but energy storage and innovations in grid infrastructure and management can address this problem.[23] Many technologies have been developed with the aim of offering storage, but to date only pumped hydro schemes have achieved significant penetration. Growth in hydro is constrained by geography and cost. Emerging technologies do not share the geographical constraints and their potential cost is lower than pumped hydro, but they will require utilisation of advanced storage and distribution technologies. Different storage technologies are suited to different installation capacities and duration of storage, as illustrated in the figure below.

Energy storage and continuous supply technologies

Application of different storage technologies in terms of duration and electrical capacity (CAES = compressed air energy storage).  Source: Renewable Energy Norway op.cit.

Technologies in use or under development that have the potential to provide solutions to the intermittency problem of renewable energy sources are discussed briefly below.

Battery systems

Significant advances are being made in the development of battery or electrochemical storage options. Examples of current installations, and research and development for use in power networks in this field, include the following:

  • lead–acid batteries of the conventional type are only commercially viable in small installations or in high–value applications for large (i.e. grid) systems owing to the high cost per kWh.[24] CSIRO is developing the ‘Ultra battery’ which combines the best energy storage characteristics of a conventional lead acid battery with the high power density characteristics of a super–capacitor. The battery is targeted at hybrid car applications and has already been prototyped. A large stationary energy storage version for renewable/intermittent supply applications is in the planning stage.[25] The discharge and charge power is expected to be 50 per cent higher and its cycle life at least three times longer than that of the conventional lead–acid counterpart.
  • sodium–sulphur high–temperature battery: the 51 MW Futamata wind farm in Japan is incorporating 34 MW of sodium–sulphur (NaS) batteries and became the largest combined wind and storage installation in the world when completed in May 2008.[26] The technology is expected to be suited to upsizing up to several tens of MW.
  • vanadium redox storage flow cells are used on King Island to store wind energy (200 kW for 4 hours, 400 kW maximum output), to store excess energy, and to reduce the requirement for diesel generator back–up.[27] In Ireland, a 2 MW, 12 MWh vanadium flow battery is being installed to provide 3 MW of pulse power for 10 minute periods every hour in order to deal with short–term volatility in wind generation – studies estimate that 700 MW of storage could be used across Ireland as wind expands to 3000 MW of installed capacity.[28] Vanadium–redox batteries are to be installed with photovoltaic solar panels and wind turbines at the remote fishing community of Windy Harbour in WA, and on Cockatoo Island and the Environmental Research Institute for Art at Homebush in Sydney.[29]
  • demonstration of a 500 kWh zinc–bromine battery at CSIRO’s National Solar Energy Centre in Newcastle.[30]

Upscaling and installation of innovative electrochemical systems are not without problems. Development of the Regenesys™ system of sodium bromide–sodium polysulphide flow cells has been cancelled following engineering difficulties encountered in building operational–scale 12 MW storage plants in Tennessee and at Little Barford in the UK.[31] However, installations of fuel cells of this and other chemical types are likely in the future following further development: the Regenesys system was designed to be readily upscaleable by increasing the size and number of electrolyte tanks to enlarge storage capacity and the discharge (i.e. supply) period, for example up to several days. 

Hydrogen

Energy from renewables can be used to produce alternative fuel in the form of hydrogen from water by electrolysis (using an electric current) or by thermolysis (by heating). Both processes can be coupled with an intermittent renewable energy source such as a wind turbine for hydrogen production, and can also provide load–levelling in stand–alone or electricity utility networks by using excess or off–peak electricity to generate hydrogen for later use.[32] Whilst electrolysis is a mature technology, it is extremely energy–intensive and probably best suited to large renewable energy projects in areas remote from the electricity grid such as the proposed hot fractured rock sites in outback Queensland, NSW and SA, where hydrogen could be piped or trucked to major centres for conversion to stationary and transport (ie fuel for vehicles) energy.

Another approach to hydrogen generation is the dissociation of ammonia into hydrogen and nitrogen. A research grant has been provided to demonstrate this system and deploy it as a solar energy storage system near Whyalla SA, where four 400 m2 solar dishes will be installed to concentrate sunlight and provide the heat required to split ammonia into nitrogen and hydrogen for storage. When power is required, the gases are recombined which gives off heat to boil water and generate electricity through a steam turbine.[33]

Thermal systems

Thermal systems make use of heat storage in various systems, including ice storage, hot water, molten salts and other materials with high heat capacity. An Australian innovation in thermal energy storage in the form of hot water from concentrated solar collectors has recently received substantial US financial backing for commercial–scale development.[34] The ‘Ausra’ storage system being developed by Dr David Mills, formerly of Sydney University, has received US$40 million in venture capital for a 175 MW storage system which will be used to generate backup power to provide baseload for up to 24 hours from steam–driven turbines. Backers claim that this power will be cheaper than nuclear power on an unsubsidised basis, and cheaper than carbon–capture coal.

Cooma–based company Lloyd Energy has developed a graphite block storage system in combination with solar towers and concentrating mirror arrays.[35] Following demonstration of the technology at the company’s site in Cooma, an eight–tower solar array system is now under construction in Lake Cargelligo in western NSW.[36] The company also plans to construct a solar tower system with graphite blocks comprising 54 towers in Cloncurry in Queensland to provide all power requirements of the town, 24 hours a day.[37]

Conclusion

This paper has provided a description of some of the major technologies under development and commercialisation in the renewable energy sector today. The suite of technologies and resources available present a promising outlook for the rapid and widespread deployment renewable energy and the eventual full replacement of hydrocarbon energy sources. However, many of these technologies are in their infancy, and other (mainly economic) barriers to the realisation of a low–carbon energy sector must also be overcome.[38]

The rate and extent of development, commercialisation, and deployment of renewable energy technologies will be highly dependent on the energy policy framework in the coming decades and the provision of incentives for clean energy sources and/or disincentives for emissions–intensive energy sources, as well as other developments relating to energy security issues such as international energy markets. Indications are, however, that under the right conditions, the technology will not be limiting.

Appendices

Operating and planned renewable energy technology installations in Australia

As at February 2009, the installed renewable energy capacity in Australia was 9945 MW. Hydro power accounts for 80% of this, followed by wind at 13%. The number and capacity of wind farms has grown strongly in the last few years and this trend is expected to continue. The bioenergy sector is expected to have moderate growth, but potential capacity is limited by the amount of waste stream material available on the one hand, and the economic and/or ethical feasibility of converting food cropping agriculture to biomass or ethanol production.

 

Number of installations by State/Territory

 

 

Technology

NSW

Qld

Vic

Tas

WA

SA

NT

ACT

Total installations

Total capacity MW

Hydro & hydro pump

35

11

24

31

2

1

 

2

106

7938

Wind

5

3

8

8

15

10

 

 

49

1272

Bioenergy total

28

41

24

4

14

9

1

3

124

731

-Bagasse

5

23

 

 

1

 

 

 

29

454.5

-Black liquor[39]

1

1

1

 

 

 

 

 

3

76.5

-Landfill gas

15

12

16

3

12

6

+1

3

68

149.6

-Sewage gas

5

4

5

1

1

2

 

 

18

35.4

-Wood waste

1

 

1

 

 

1

 

 

3

9

-Food & agric waste

1

1

1

 

 

 

 

 

3

5.6

Photovoltaic

5

3

5

 

5

3

7

 

28

4.2

Geothermal

 

1

 

 

 

 

 

 

1

0.12

Summary of installed renewable energy production capacity in Australia February 2009 and its spread across the technologies. Source: Clean Energy Council.

In early 2009 about 961 MW additional capacity was under construction, almost entirely in wind (752 MW) and hydro (176 MW). Another 6 555 MW was classed as in development, with wind again dominating at 88.4 per cent, and bagasse and photovoltaics both 2.5 per cent; less than 50 MW or 0.75 per cent of all projects in development are in hydro, suggesting that there is limited further development capacity. A further 5300 MW of projects are classed as under evaluation. Wind again dominates at 75 per cent, but wave and tidal projects jump to almost 17% in terms of total installed capacity under evaluation.

 

 

Number of projects by State/Territory
 (in construction / in development / evaluation stage )

Total projects

Total capacity MW[40]

Technology

NSW

Qld

Vic

Tas

WA

SA

NT

ACT

In construction

In development

At evaluation

In construction

In development

At evaluation

Hydro & hydro pump

4/2/4

-/-/1

7/1/-

-/5/-

-/-/-

-/-/1

-/-/-

-/1/2

11

9

8

176

49

99

Wind

2/18/12

-/2/3

1/23/6

1/2/1

-/6/2

3/4/3

-/1/-

-/-/-

7

56

27

752

5795

3968

Bioenergy

 

 

 

 

 

 

 

 

 

 

 

 

 

 

- Bagasse

-/-/-

-/3/-

-/-/-

-/-/-

-/1/-

-/-/-

-/-/-

-/-/-

-

4

-

-

165

-

- Black liquor[41]

-/-/-

-/-/-

-/-/-

-/1/-

-/-/-

-/-/-

-/-/-

-/-/-

-

1

-

-

2.5

-

- Landfill gas

2/2/1

-/-/-

-/1/-

-/-/-

-/1/1

-/-/-

-/-/-

-/-/-

2

4

2

25

8

28

- Sewage gas

3/2/-

-/-/-

-/2/-

-/-/-

-/-/-

-/-/-

-/-/-

-/-/-

3

4

-

2

3

-

- Wood waste

-/-/1

-/-/1

1/-/1

-/-/2

-/2/-

-/-/1

-/-/-

-/1/-

1

3

6

2

10

195

- Food & agric waste

-/3/-

-/-/-

-/1/-

-/-/-

-/1/-

-/-/-

-/1/-

-/-/-

-

6

-

-

21

-

Photovoltaic

1/1/-

-/-/-

-/1/2

-/-/-

-/1/1

-/1/-

1/-/-

-/-/-

2

4

3

1

158

11

Geothermal

-/-/-

-/-/-

-/-/-

-/-/-

-/-/-

1/1/1

-/-/-

-/-/-

1

1

1

1

50

110

Solar thermal

2/3/-

-/2/-

-/1/-

-/-/-

-/-/-

-/2/-

-/-/-

-/-/-

2

8

-

6

275

-

Wave/tidal

-/-/-

-/-/-

-/1/2

-/2/1

1/1/1

-/-/1

-/-/1

-/-/-

1

4

6

0.1

29

886

Energy crops

-/-/-

-/-/-

-/-/-

-/-/-

-/-/1

-/-/-

-/-/-

-/-/-

-

-

1

-

-

5

Grand totals

14/28/18

-/7/5

9/30/11

1/10/4

1/12/6

4/8/7

1/2/1

-/2/2

30

98

54

961

6556

5302

Summary of renewable energy projects in construction, in development or at the evaluation stage, as at February 2009, distributed by jurisdiction and technology type. Source: Clean Energy Council. Projects with no data for installed capacity are excluded from this compilation.

 

 

Renewable energy projects in construction

Legend

This map, and an extensive spreadsheet describing the renewable power station types and locations, are available at http://www.ga.gov.au/renewable/

 

Location of the renewable power stations in Australia

Most of the 603 installations are small plants—116 less that 1 MW capacity and 232 less than 5 MW capacity. As larger scale plants are built they are more likely to be concentrated in the areas where the energy source being tapped is best developed:

  • Wind—southwest WA, southeast SA, coastal Victoria and Tasmania
  • Geothermal—northeast and east SA, Hunter Valley NSW
  • Wave—southwest WA, coastal SA, western Victoria and western Tasmania
  • Tidal—northern WA, NT, parts of northern Queensland
  • Solar thermal and PV—non-coastal mainland Australia, especially inland NSW, SA, Qld, NT and WA

 

The largest operating installations for each renewable energy technology in Australia

The location and generating capacity for the largest Australian installation for each of the renewable energy technology types is as follows (as at May 2009):

Technology

Capacity MW

Location

Hydro

1500

Snowy Mountains Scheme, Tumut 3

Wind

140

Woolnorth stages 1, 2 & 3. NW corner of Tasmania

Bioenergy:

 

 

-bagasse

63

CSR Pioneer 2 Bagasse cogeneration, Brandon, near Townsville

-black liquor

54.5

Paperlinx factory, Maryvale Victoria

-landfill gas

12.65

Lucas Heights landfill II, Sydney

-sewage gas

9.1

Carrum Downs 2, Melbourne

-wood waste

5

Stapylton, Qld

-food & ag waste

3.9

Dairy, grease trap waste and general food is used to generate power and fertilizer in the Camellia plant, Parramatta NSW

Photovoltaic

0.67

Sydney Olympic Park, numerous small rooftop arrays

Geothermal

0.12

Birdsville Qld, powered by hot artesian bore water

Wave

0.4

Oceanlinx technology, Port Kembla NSW

Back to top

Examples of some large proposed renewable energy technology projects

In order for renewables to grow at a pace able to meet growing energy demand and progressively replace coal and hydrocarbons, the size of installations needs to grow so that economies of scale can be achieved and efficient energy distribution infrastructure developed. A new coal-fired power plant in Australia would be in the order of 1000 MW capacity, much larger than any renewable power installation operating today. However, the capacity of different types of individual renewable power generators is increasing, and in the foreseeable future these could be grouped into “farms”, with a generating capacity in the same order of magnitude as a coal-fired power plant.

 

Examples of large planned renewable energy facilities either in, or applicable to Australia

Type

Largest existing or planned installation

Location

Timing

Wind

1 GW offshore windfarm, 341 turbines. Individual turbines now < 7 MW

London Array, Kent UK

Phase 1 (175 turbines) by 2012

Wave

4 MW OWC device

Isle of Lewis, Scotland

Delayed owing to financial difficulties

7 MW ‘Wave Dragon’ anchored overtopping device

Pembrokeshire coast, Wales

Currently testing, could lead to 70 MW installation in Irish Sea

Ocean current

300 MW array of sea channel turbines, each 1 MW

Wando Hoenggan waterway, southern Korea

2015

Solar

1000 MW photovoltaic array

Australia, site tba

Bids to be assessed in 2010

 

850 MW parabolic dish + Stirling engine

Solar One, California USA

2014

 

400 MW solar trough

Ivanpah, California USA

2012

 

550 MW photovoltaic array

Topaz, Carrizo, California USA

2013

 

177 MW lineal Fresnel collector

Carrizo, California USA

2010

Geothermal

5 – 10 GW hot fractured rock

Innamincka, Australia

Unknown – difficulties with drilling technology

Biomass

300 MW wood waste

Oglethorpe Ga USA

2015

 

The cost of electricity production from renewable energy technologies

Overall, the cost of electricity generated from renewables is significantly higher than for coal and gas. However this differential is markedly less when renewables are compared with the cost of coal and gas-based generation including carbon capture and sequestration. The adoption of clean coal technology is predicted to increase the cost of wholesale electricity by 50 per cent and the price to consumers go up by a quarter[42]. The cost of power from biomass, wind and wave power is already within the range of costs for coal generation with carbon capture and sequestration, and technological advances and upscaling promise to reduce these costs further.[43]

Renewable type

Reliability

Cost $/MWh*
Now /  Projected

Comments

Biomass

High

80

50

Mature; further development & improved waste management needed to cut cost,and possibly impacts on food production.

Wind

Low, intermittent

70

40–45

Established; rapid upscaling is bringing down costs.

Photovoltaics

Medium-high, intermittent

180–220

?

R&D in progress to increase efficiency & reduce cost. Scale of planned installations rapidly increasing. Requires large land area.

Solar thermal concentration

Medium-high, intermittent

135–185

60

Development in part driven by conjoined installations at coal plants to improve coal efficiency. Requires large land area.

Solar tower

Medium-high, intermittent

?

?

Requires large land area.

Wave

Medium-high,

50

50

Several small-scale installations overseas. Agreements in place for some small (upscaleable) installations here.

Tidal

High, intermittent

410

?

Lower costs dependent upon larger scale; trend is away from the very high capital cost barrage types towards submerged turbine arrays.

Geothermal aquifer

High

1.40–1.70

1.40–1.70

Mature very small scale. No significant prospects for upscaling in Australia.

Geothermal hot dry rock

High

50–60

50–60

At resource definition and demonstration stage High potential areas are remote. Potential very large-scale energy source.

* For comparison, coal $28–0; clean coal + carbon capture $52-105; gas $37–54; gas with carbon capture 52–94; nuclear $40–65.    
Present and project future cost of different forms of renewable energy technology

Another sleeper issue in energy pricing is the additional external costs of various sources of energy as they impact upon climate change, and (indirectly) human health. These costs are estimated to be $19/MWh for gas, $42/MWh for black coal, and $52/MWh for brown coal, and for the renewables are $5/MWh for solar PV and $1.50/MWh for wind. Thus most forms of renewable energy are cost-competitive with coal and gas when these additional costs are considered.[44]



[1].    Wyld Group, High temperature solar thermal technology roadmap, Report prepared for the New South Wales and Victorian Governments, 2008, viewed 7 July 2009, http://www.coag.gov.au/reports/docs/HTSolar_thermal_roadmap.pdf

[2].    International Energy Agency, World Energy Outlook 2008, OECD/IEA, 2008, viewed 7 July 2009, http://www.worldenergyoutlook.org/docs/weo2008/WEO2008_es_english.pdf

[3].    EnviroMission Ltd, Technology overview, EnviroMission website, viewed 7 July 2009, http://www.enviromission.com.au/IRM/content/technology_technologyover.html

[4].    A Stirling engine converts heat into mechanical power by moving air or other gas between hot and cold reservoirs.

[5].    The capacity of an electricity generating system is the maximum power (or energy per unit time) that can be delivered, measured in units of Watts: 1 MW is 1 million watts; 1 kW is 1 thousand watts. Electricity generation is the energy delivered (power multiplied by time), measured in watt–hours: 1 MWh is 1 million watt–hours.

[6].    A Jolley, Technologies for Alternative Energy, Climate change working paper no. 7, Centre for Strategic Economic Studies, Victoria University, March 2006, viewed 7 July 2009, http://eprints.vu.edu.au/397/1/07_Jolley_Technologies_for_Alternative_Energy.pdf

[7].    Origin Energy, SLIVER technology, viewed 6 July 2009, http://www.originenergy.com.au/1233/SLIVER-technology

[8].    NS Lewis, ‘Toward Cost–Effective Solar Energy Use’, Science, vol. 315, 9 February 2007, p. 798.

[9].    Solar Systems, HCPV technology: factsheet – the technology, viewed 7 July 2009, http://www.solarsystems.com.au/HCPV_technology.html

[10]. BA Goldstein, AJ Hill, AR Budd, FL Holgate and M Malavazos, ‘The national outlook – Australia’s hot rocks’, Proceedings of the Sir Mark Oliphant International Frontiers of Science and Technology Australian Geothermal Energy Conference, Geoscience Australia Record 2008/18, 2008, p. 13, viewed 7 July 2009, http://www.ga.gov.au/image_cache/GA11825.pdf

[11]. Enercon, Windblatt, Enercon Magazine for wind energy, issue 4, 2007, p. viewed 6 July 2009, http://www.enercon.de/www/en/windblatt.nsf/vwAnzeige/66BD14BABA22BCA2C12573A7003FA82E/$FILE/WB-0407-en.pdf

[12]. A Jolley, Technologies for Alternative Energy, op.cit.

[13]. Hydro Tasmania, Study of Tidal Energy Technologies for Derby, Sustainable Energy Development Office of Western Australia, Hobart, 2001, viewed 7 July 2009, http://www1.sedo.energy.wa.gov.au/uploads/Derby%20Tidal%20Energy%20Study%20-%20Executive%20Summary_21.pdf

[14]. BioPower Systems, BioSTREAMTM: in–stream tidal power system, viewed 6 July 2009, http://www.biopowersystems.com/biostream.php

[15]. BioPower Systems, Ocean power pilot program accelerated through MOU with Hydro Tasmania, media release, 6 May 2008, viewed 6 July 2009,   http://www.biopowersystems.com/briefs/BPS_MEDIA%20RELEASE-06MAY2008.pdf

[16]. ‘Wave energy pilot plant planned’, Sydney Morning Herald, 19 May 2009, viewed 8 July 2009, http://www.smh.com.au/environment/energy-smart/wave-energy-pilot-plant-planned-20090519-bdr4.html

[17]. Lunar Energy, British firm announces world’s largest tidal power development – Lunar Energy seals £500m tidal power deal with Korea, media release, 11 March 2008, viewed 7 July 2009, http://www.lunarenergy.co.uk/newsDetail.php?id=14

[18]. P McKenna, ‘The coolest source of energy ever’, New Scientist, 22 November 2008, p. 28, viewed 8 July 2009, http://parlinfo.aph.gov.au/parlInfo/download/library/jrnart/OFLS6/upload_binary/ofls61.pdf

[19]. ResourceSmart, Mini hydro delivers more green energy to Victorians, media release, 2 July 2008, viewed 7 July 2009, http://www.resourcesmart.vic.gov.au/media_releases_3885.html

[20]. SA Water, Mini–Hydro, SA Water website, Government of South Australia, viewed 7 July 2009, http://www.sawater.com.au/SAWater/Environment/SaveWater/Innovation/Mini-Hydro.htm

[21]. S Needham, The potential for renewable energy to provide baseload power in Australia, Research paper, no. 9, 2008–09, Parliamentary Library, Canberra, 2008, viewed 6 July 2009, http://www.aph.gov.au/library/pubs/rp/2008-09/09rp09.pdf

[22]. House of Lords Select Committee on the European Community, Electricity from Renewables, HL Paper 78–I, June 1999.

[23]. N Jenkins and G Strbac, ‘Increasing the value of renewable sources with energy storage’, in Renewable energy storage, Institution of Mechanical Engineers (UK), Seminar Publication 2000–7, 2000.

[24]. A Collison, ‘The costs and benefits of electrical energy storage’, in Renewable energy storage, Institution of Mechanical Engineers Seminar Publication 2000–7, 2000.

[25]. CSIRO, Addressing National Challenges: Science sustaining Australia’s future, February 2007, viewed 7 July 2009, http://www.csiro.au/files/files/pg5m.pdf

[26]. R Baxter, A call for back–up: how energy storage could make a valuable contribution to renewables, Renewable Energy World Magazine, vol. 10, issue 5, September/October 2007, viewed 7 July 2009, http://www.renewableenergyworld.com/rea/news/article/2007/09/a-call-for-back-up-how-energy-storage-could-make-a-valuable-contribution-to-renewables-51463

[27]. Hydro Tasmania, Hydro Tasmania’s King Island wind farm, fact sheet, viewed 7 July 2009, http://www.taswind.com/Documents/Renewables%20Development/5882Roaring40s.pdf

[28]. R Baxter, A call for back-up, op. cit.

[29]. Renewable Energy World, Australian outback gains system to store solar and wind energy, Renewable Energy World Magazine vol. 5, 9 May 2007, viewed 7 July 2009, http://www.renewableenergyworld.com/rea/news/article/2007/05/australian-outback-gains-systems-to-store-solar-and-wind-energy-48429;

[30]. EnergyCurrent online news service, Australia awards five renewable projects, 5 February 2007, viewed 7 July 2009, http://www.energycurrent.com/index.php?id=3&storyid=2308 

[31]. ‘Innogy pulls plug on Regenesys’, The Guardian, 16 December 2003, viewed 7 July 2009, http://www.guardian.co.uk/business/2003/dec/16/utilities; RWE discontinues Regenesys program, Electricity Storage Association newsletter, February 2004, p. 4, viewed 7 July 2009, http://electricitystorage.org/pubs/2004/Newsletter_Feb_2004.pdf

[32]. Department of Resources, Energy and Tourism, Australian Hydrogen Activity 2008, Australian Government, 2008, viewed 7 July 2009,   http://www.ret.gov.au/energy/clean_energy_technologies/energy_technology_framework_and_roadmaps/hydrogen_technology_roadmap/Documents/HYDROGEN%20ACTIVITY.pdf .

[33]. Department of Resources, Energy and Tourism, Australian Hydrogen Activity 2008, op.cit.

[34]. M Peacock, ‘Solar takes off with US power supply deal’, ABC News, 2 October 2007, viewed 7 July 2009, http://www.abc.net.au/news/stories/2007/10/02/2048420.htm

[35]. Lloyd Energy Systems website, viewed 7 July 2009, http://www.lloydenergy.com/home.htm

[36]. J Bannon, ‘Solar alliance’, Cooma–Monaro Express, 4 June 2009, viewed 7 July 2009,      http://www.coomaexpress.com.au/news/local/news/general/solar-alliance/1531909.aspx

[37]. Energy Matters, Queensland town to be fully solar powered, Renewable Energy News, 23 February 2009, viewed 7 July 2009,   http://www.energymatters.com.au/index.php?main_page=news_article&article_id=331

[38]. For further discussion of these issues see S Needham, op. cit.; and the Parliamentary Library climate change website, viewed 6 July 2009, http://www.aph.gov.au/library/pubs/ClimateChange/responses/mitigation/emissions/renewable.htm 

[39].  Black liquor is a by-product of the paper making process; boilers are used to capture and burn the liquor to produce heat and recover processing chemicals which are fed back into the process.

[40].  Rounded where value is greater than 1.

[41].  Black liquor is a by-product of the paper making process; boilers are used to capture and burn the liquor to produce heat and recover processing chemicals which are fed back into the process.

[42].  John Arlidge, Peter Gill and Keith Orchison, Powering Australia: the business of electricity supply 2007–08, Focus Publishing, Woolloomooloo, 2007.

[43].  Tom Biegler 2009. Externalities – the reality of hidden costs of electricity ATSE Focus 2009, vol 155.

[44].  AREVA, Submission to the Garnaut Climate Change Review,     2008, http://www.garnautreview.org.au/CA25734E0016A131/WebObj/D0851413GeneralSubmission-AREVAAustralia/$File/D08%2051413%20%20General%20Submission%20-%20AREVA%20Australia.pdf, accessed on 16 September 2008;  IPCC, ‘Carbon dioxide     capture and storage’, Special report. Summary for policy makers and technical summary, 2005, http://www.ipcc.ch/activity/ccsspm.pdf, accessed on 17 May 2008,table TS10; John Boshier, Interview with the author, 7 April 2008: http://www.abc.net.au/7.30/content/2007/s2210205.htm, accessed on 12 May 2008.

 

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