The Canberra Times recently published an article, rather misleadingly entitled "Generating solar energy in the dark", which looked at the use of purified graphite for thermal energy storage.

The company developing the technology is called Lloyd Energy Systems, which is prototyping solar energy storage, a wind-to-heat plant and a small-scale plant that combines water treatment, energy storage and steam turbine generation.

The company has received a $5 million Federal Government grant as part of its advanced energy storage technology program in the western NSW town of Lake Cargelligo, with Country Energy agreeing to purchase the power generated. Lloyd Energy also has an agreement with Ergon Energy in Queensland to build a $30million plant at Cloncurry in Queensland, partially funded by the Queensland state government, which the Sydney Morning Herald reported on last year.

[Lloyd Energy CEO] Mr Hollis said large amounts of coal-fired energy were lost during long transmission to remote areas. As power loads built up over time, mainly because of demand for air-conditioners, the grid could no longer cope in peak periods. Towns at the end of the line suffered the most from power shortages.

"We're putting environmentally friendly generation out at the end of the branches of the tree if you like, so it can pump energy back in when the branches are in trouble," he said. "It actually serves three purposes. Firstly, it is a renewable energy replacement for coal. Secondly, it avoids the country energy authorities having to upgrade their transmission lines so they can get more power out in the peak." The third benefit was having an energy source at the end of the line that could return power into the grid.

Sixteen full-scale models would go to Lake Cargelligo and 54 to Cloncurry. The system's mobility and flexibility had caught the attention of key Australian mining companies, which use diesel and gas generators.

Mr Hollis said making renewable energy available when it was required added to the system's value. ... "You can store thermal energy in a lot of things, but high-purity graphite is an extremely efficient way of storing it it doesn't have any losses. You can move the heat in and out very quickly."

Graphite based storage does not seem to have been used anywhere else in the world thus far. Storage for renewable energy has usually been limited to compressing air underground (Compress Air Energy Storage or CAES), where it can later be released under pressure, or pumped hydro, where the power is used to pump water back up into dams that can generate hydro-electricity. While both techniques are effective, they require suitable locations and complex infrastructure to be put in place.

The Queensland project will make Cloncurry the first town in Australia to rely exclusively on solar power, produced by a concentrated solar power (CSP) system. The system contains almost 7200 mirrors, which will guide the sun's rays into holes in the bottoms of 54 elevated graphite cubes, heating them to 1800 degrees (C). The stored heat is then used to generate steam for turbines on demand. The company claims the turbine will use less water than falls in an average year on the power station's roof.




Wind to Heat on King Island

A third system using the graphite system is being planned by CBD Energy, which has licensed the Lloyd technology and will build a wind-powered version of the system on King Island. The island, in the Bass Strait north-west of Tasmania, currently relies primarily on diesel to generate power for its 1800 residents.

The joint venture with Hydro Tasmania is not expected to make the island wholly powered by renewable energy, but it will eliminate the need for 1.25 megalitres of diesel fuel a year, says CBD's chief engineer, John Giannasca.

CBD plans to install two megawatts of wind turbines to supplement existing systems along with six graphite blocks. The blocks are each the size of a standard shipping container, and will be heated to 800 degrees (C).



Some solar panels will be also be installed for periods when the island is without wind, and there are ongoing investigations into harnessing ocean current and tidal energy in the region.

CBD Energy is run by ex-Impulse Airlines chief Gerry McGowan, with the company partly owned by German clean energy company Solon. CBD is also looking to develop solar energy projects in Australia, with plans for the first operation to be set up in the northern NSW town of Moree.

Graphite energy storage in context

King Island received a lot of press attention for an earlier project to store energy using Vanadium Redox flow batteries that began in 2003.



The company involved in that initiative, Pinnacle VRB, has since changed name to Cougar Energy and doesn't seem to have any active VRB projects going.

Another Australian company developing a slightly different form of Vanadium based batteries (Vanadium Bromide) is VFuel, though there hasn't been much news from them in some time either. Both VFuel and Pinnacle/Cougar are using technology pioneered at the University of NSW.



What will happen to the flow battery installation isn't clear, though a visiting parliamentarian (pdf) reported in 2004 that "The vanadium batteries would appear to best suit the ironing out of the wind fluctuations rather than holding larger quantities of power. The battery is expensive and takes up considerable space" and that graphite was being considered as an alternative.

TreeHugger noted last year that the advantage the Lloyd Energy graphite system has is that they have apparently managed to figure out how to refine low grade graphite into high quality crystalline graphite, and the storage capacity “ranges from around 300kWh (thermal) per tonne at a storage temperature of 750°C to around 1000kWh (thermal) per tonne at 1800°C.”.

The Australian Greenhouse Office has a review paper on Energy Storage Technologies (pdf), published in 2005, which includes a brief look at graphite in a section on thermal energy storage.

Thermal energy storage systems use material that can be kept at high temperatures in insulated containments. Heat recovered can then be applied for electricity generation using steam Rankine cycle or other heat engine cycles. Energy input can, in principle, be provided by electrical resistance heating but the overall round trip efficiency will be low. However, as with thermochemical energy storage, thermal systems have considerable advantages when integrated with Concentrating Solar Power (CSP) technologies (ie parabolic troughs or dishes, central receiver/heliostat systems and Linear Fresnel systems).

Integration of thermal storage for several full load hours, together with new storage materials and advanced charging/discharging concepts, would allow for increased solar thermal electricity production without changing the power block size (ECOSTAR, Nov 2004). Provided that the storage is sufficiently inexpensive, this would lower the levelised energy cost, and additionally increase the dispatchability of the electricity generation.

The kind of storage system used for solar energy storage depends on the Concentrating Solar Power (CSP) technology, the heat transfer medium used and the required temperature of operation. In general, high-temperature thermal storage development will need several scale-up steps over an extended development time before market acceptance will be achieved.

Storage systems for thermal energy storage need to:
• be efficient in terms of energy loss and temperature drops
• have low cost
• have a long service life
• have low parasitic power requirements.

The development of storage systems for high pressure steam and pressurized, high temperature air, is especially challenging. If or when developed, such storage systems would lead to a significant drop in CSP electricity costs. The high-temperature thermal storage technologies utilised or under development now are (ECOSTAR, Nov 2004):

Molten salt storage and Room Temperature Ionic Liquids (RTILs)

• State of the art is the 2-tank molten salt storage tested in the “Solar Two” Central Receiver Solar Power Plant demonstration project in California, combined with using molten salt as heat transfer fluid. The use of new, so called Room Temperature Ionic Liquids (RTILs) has recently been proposed. RTILs are organic salts with negligible vapour pressure in the relevant temperature range and a melting temperature below 25°C. Room temperature ionic liquids are new materials that have the potential to be stored at temperatures of many 100s of degrees without decomposing. It is not yet clear whether they are stable up to the temperature level required for CSP and also whether they may be produced at reasonable costs.

Concrete Storage

• The concept of using concrete or castable ceramics to store energy at high temperatures for parabolic trough power plants with synthetic oil as the heat transfer fluid (HTF) has been investigated in European projects. The implementation of a concrete storage system is claimed (ECOSTAR, Nov 2004) to be able to be realised within less than 5 years.

Phase Change Materials (PCM)

• Phase change materials are materials selected to have a phase change (usually solid to liquid) at a temperature matching the thermal input source. The high “latent heat” in a phase change offers the potential for higher energy storage densities than storage of non phase change high temperature materials. Because a solid/liquid phase change is involved, a heat transfer fluid is needed to move heat from source to PCM. At present, two principle approaches are being investigated:
- encapsulation of small amounts of PCM
- embedding of PCM in a matrix made of another solid material with high heat conduction.
• The first measure is based on the reduction of distances inside the PCM and the second one uses the enhancement of heat conduction by other materials (e.g. graphite). Storages based on PCM are in an early stage of development but the cost target is to stay below A$34/kWh based on the thermal capacity. Although the uncertainties and risks of the PCM storage technology are in a medium range, the technology time required for full development and commercial implementation is likely to be more than 10 years (ECOSTAR, Nov 2004).

Storage for air receivers using solid materials

• Storage types using solid material for sensible heat are normally used together with volumetric atmospheric or pressurized air systems. The heat has to be transferred to another medium, which may be any kind of solid with high density and heat capacity. Another innovation is to develop for pressurised closed-air receivers a storage container that has to be pressure resistant up to about 16-20 bar depending on the gas turbine pressure ratio.
• For both cases the time for development and implementation is considered to be between 5 to 10 years and the risks and uncertainties are in the medium range (ECOSTAR, Nov 2004).

Storage for saturated water/steam

• The steam drum, which is a common part in many steam generators, is often used to provide process heat storage in industry. The main problem is the size of the steam vessel for larger storage capacity and the degradation of steam quality during discharging. However, this storage type is ideal as buffer storage for short time periods of several minutes, to compensate shading of the solar field by fast moving small clouds. Using appropriate encapsulated PCM inside the storage could enhance the storage capacity because the latent heat content can be used to slow down the temperature and pressure decrease and enable smaller storage vessels for the same thermal capacity.
• Recently, underground thermal energy storage has been proposed again as a lowcost solution to high-temperature, low-loss thermal storage for CSP systems (Mills et al, Nov 2004). It involves storage of water under pressure in deep metal lined caverns where the pressure is contained by the surrounding rock and the overburden weight.

High-purity graphite.

• This readily available material has the attractive property of increasing its heat storage capacity as the temperature of storage rises. However, the relatively low temperatures of solar thermal systems are not optimal for this storage medium unless the graphite storage blocks could be positioned at the very high temperature focus of a concentrating solar collector.

For another good description of a range of energy storage technologies, try Richard Baxter's book "Energy Storage: A Nontechnical Guide".

One obvious advantage for graphite is that carbon is extremely common, unlike some of the minerals used in various battery technologies and so there will be no meaningful material "limits" to the creation of these. Perhaps one day we'll see CO2 being sequestered in the form of graphite blocks, ready to be installed into CSP power stations.

On semi-related news, energy storage has also been getting some attention in The Economist lately, courtesy of EEStor's ultracapacitor technology.

The SMH has a report on a solar thermal power project in Queensland - "Cloncurry so hot it's first on the solar block" no doubt helped along by Andrew McNamara.

IT'S HOT in Cloncurry. Bloody hot. Hot enough to power the homes for all the outback town's 4828 residents with heat from the sun. That is what the Queensland Government is hoping to do with a $7 million solar thermal power station that would make the former copper mining town the first in Australia to rely completely on solar power.

The Queensland Premier, Anna Bligh, yesterday announced the north-west Queensland town had been chosen as the site for a "groundbreaking" 10-megawatt plant that will use 8000 mirrors to reflect sunlight onto graphite blocks. Water will be pumped through the blocks to generate steam that will operate a turbine electricity generator. ...

"This is an example of the diversity of clean energy that is available in Australia because of the renewable resources at our disposal," said the energy council's chief executive, Dominique La Fontaine.

An Australian company, Lloyd Energy Storage, designed the unique graphic-block storage system. A forest of mirrors, each three metres by two metres, will reflect the sun's rays up into 50 10-tonne blocks perched atop 15-metre towers. Enough heat will be stored in the blocks to service peak daytime needs and overnight demand. Less water than falls in an average year on the power station's roof will be used in the turbine.

The project follows a decision last year by the Federal Government to give $75 million to a $420 million project to build a large-scale solar concentrator in Mildura in Victoria. That project is expected to start next year and reach full capacity by 2013. Using high-performance solar cells developed to power satellites, it could power as many as 45,000 homes.

The IHT has an update on the bioplastic industry - "Bioplastics have a small but growing market".

For Dennis McGrew, chief executive of NatureWorks, the high price of crude oil and natural gas is not unwelcome news. NatureWorks, formerly Cargill Dow, produces a plastic made from plant stalk, not fossil fuel. McGrew, a former plastics executive at Dow Chemical, says that as prices for fossil fuels soar and as the environment becomes an ever larger concern, ecofriendly plastics are becoming increasingly competitive, though they still remain a niche market.

That bioplastics are trending upward is clear. In the past month, a number of large chemical concerns have increased their commitment to market segment, including Braskem, the largest Brazilian petrochemical group, and Dow Chemical. In September, Plantic Technologies of Australia announced that DuPont would market its starch-based resins and sheet plastics in North America, a new market for a company previously limited to selling in Europe and Australi

Biopact reports that scientists have found a way to convert biodiesel byproduct glycerin into ethanol.

Recently, a way to connect the ethanol and biodiesel industries was revealed when it was determined that biodiesel could be a value-added product for ethanol plants through corn oil extraction technology (previous post). But now the link is reversed: researchers at Rice University in Houston have developed a way to convert glycerin (glycerol), a byproduct of biodiesel production, into ethanol. Both sectors are now linked and could create synergies that make both more efficient.

The glycerin-to-ethanol pathway is seen as promising, which is why the scientists behind it formed Glycos Biotechnologies to commercialise it. Once considered a valuable co-product, crude glycerol is rapidly becoming a 'waste product' with a disposal cost attributed to it - a result of the biodiesel boom. ...

The implications of this research are so promising that the process may be commercialized before cellulosic ethanol. Gonzalez partnered with Paul Campbell, who researches, develops and markets blends of microbes for industrial, agricultural and environmental markets, to form Glycos Biotechnologies Inc. The company, which was funded by Houston-based venture capital fund DFJ Mercury, expects to complete its pilot plant in early 2008.

TreeHugger has a post on "Using Sweet-Toothed Bacteria to Produce Hydrogen".

Aside from crop-based biofuels, few sectors of renewable energy have attracted as much attention as microbial fuel cells. With companies like LS9 and Amyris leading the way, the idea of engineering bacteria to produce new sources of energy has become an increasingly marketable one as gas prices continue to soar.

This high level of interest has also prompted a groundswell of new research in universities and government-funded science institutions aimed at finding ways to make these nascent technologies more practical and efficient. Scientists from Washington University and the Agricultural Research Service (ARS) recently formed a partnership to study how electrochemically active, biomass-eating bacteria could be used in microbial fuel cells.

Mike Cotta, who leads the ARS Fermentation Biotechnology Research Unit, and Lars Angenent, an assistant professor at WU, will use the Microbial Culture Collection - an ARS-funded database with accessions from about 87,000 freeze-dried bacteria from around the world - to specifically isolate anaerobic bacteria that could help produce hydrogen. Electrochemically active bacteria are able to transfer electrons from fuel cell sugars - which, after traveling through a circuit, can be combined with protons in a cathode chamber to form hydrogen. This can then be burned or converted directly into electricity.

Two taxa that are showing early promise include Bacteroides and Shewanella.

TreeHugger also has a demoralising report on the state of the oceans - "Increasingly Acidified Waters Could Prompt Mass Shellfish Dissolution".

If present acidification trends in the world's oceans continue unabated, mussels, oysters and other shellfish could become extinct as early as 2100. Carol Turley, a researcher at the Plymouth Marine Laboratory, is warning that these mass casualties could have severe repercussions for humans and the health of ocean ecosystems. "A lot of shellfish are an important food source for fish as well as humans. The impacts of shellfish disappearing could be massive," she explained in a recent address.

Increasing levels of dissolved carbon dioxide hinder the ability of shellfish to build their protective shells by significantly reducing the amount of free carbonate in the water. Shellfish typically absorb calcium carbonate from their surroundings and deposit it around their bodies to make their shells; higher levels of carbon dioxide, however, limit the amount of available carbonate - which otherwise could bind to free calcium ions - by forming more bicarbonate ions.

This effect is especially pronounced in deeper waters, where extremely low levels of carbonate ions, paired with higher hydrogen ion concentrations, have caused shellfish shells to actively dissolve. Indeed, several recent studies have noted a worrying rise in the Carbonate Compensation Depth (CCD), a level below which the rate of supply of calcium carbonate equals that of dissolution.

For very much the same reason, coral reefs are also likely to be hit hard as coral polyps struggle to build the tough skeletons they need to protect themselves and provide habitats for a wide variety of organisms. Fish are also likely to not escape unscathed as acidification harms their ability to fertilize their eggs.

Links:

* Technology Review - Betting on Biocrude
* Red Herring - Wind Power Gets Gust of $16M
* The Long Now - NY Times Magazine: “The Future is Drying Up”
* UPI - Duke Energy faces water shortage
* Richard heinberg - Big melt meets big empty: Rethinking the implications of climate change and peak oil
* TreeHugger - Farewell to "Flush and Forget"
* TreeHugger - The Latest on the Disappearing Honeybee Mystery
* ABC - Press freedom declining: audit
* The Australian - Our slide into secrecy and censorship