Solar-power paint lets you generate as you decorate
13:59 07 March 2008
NewScientist.com news service
Michael Marshall
A lick of solar-power paint could see the roofs and walls of warehouses and other buildings generate electricity from the sun, if research by UK researchers pays off. The scientists are developing a way to paint solar cells onto the steel sheets commonly used to clad large buildings.
Steel sheets are painted rapidly in steel mills by passing them through rollers. A consortium led by Swansea University, UK, hopes to use that process to cover steel sheets with a photovoltaic paint at up to 40 square metres per minute.
The paint will be based on dye-sensitised solar cells. Instead of absorbing sunlight using silicon like conventional solar panels, they use dye molecules attached to particles of the titanium dioxide pigment used in paints.
That gives an energy boost to electrons, which hop from the dye into a layer of electrolyte. This then transfers the extra energy into a collecting circuit, before the electrons cycle back to the dye.
While less efficient than conventional cells, dye-based cells do not require expensive silicon, and can be applied as a liquid paste.
Collision of technologies
The Swansea team's leader, David Worsley says the idea to paint the cells onto architectural steel grew out of previous research by his group into the ways steel on buildings is degraded by the elements.
They knew that paint fades in sunlight because the titanium dioxide pigment used is sensitive to sunlight. Worsely and doctoral student, Maarten Wijdekop realised they could exploit this by creating a paint that functions as a dye sensitised cell.
Wijdekop now works for steel manufacturer Corus, which is helping develop the technology.
Worsley describes the current research as "a collision between two existing technologies - one for generating electricity and one for applying paint to steel." "We should see a commercial cell in two-and-a-half years," he says.
The solar cells are built up in several layers. Firstly, a barrier of normal paint is laid directly on the steel, then the electrolyte and dye layers, and finally a clear protective film to guard against the elements.
A wind-driven device could provide an unlimited water supply by harvesting water from the air, says its Australian inventor. But critics are asking if it's too good to be true. Dr Max Whisson, a retired medical specialist turned inventor, says he has designed a highly efficient wind turbine that can run a refrigeration system to cool air and condense moisture from it. "The wind carries in the water and [provides] the power required to separate that water from the wind," says Whisson, who is based in Perth. He says there is a huge amount of water in the atmosphere that is replaced every few hours. This means the whole world could just use water from the air without disrupting the environment. Whisson says the system would even harvest significant amounts of water in areas with low humidity. He says a 4 metre square device could extract an average 7500 litres of water a day. In his design, moisture-laden air enters the system and is cooled by a drop in pressure behind the wind turbine blades, says Whisson. The air then flows into a chamber containing refrigerated metal plates covered by a non-wettable surface that causes water droplets to run off immediately into a collection point. Could it work? Full technical details of the design are not available but at least one mechanical engineer is sceptical. "I have found in general that inventors tend to enormously overstate the capacities of their devices. They just have a very rosy outlook on what their devices will do," says mechanical engineer Professor John Reizes, an adjunct professor at the University of New South Wales. "It's not until you've made one that you discover all the Reizes, who specialises in heat transfer, says he is sceptical because of the huge amount of energy that is needed to condense water. Whisson says he is well aware that a large amount of energy is required to do the job. "It's like boiling a kettle in reverse," he says. But he is confident his wind turbine, still subject to patent applications and yet to be independently tested, is efficient enough. "The wind turbine is a surprisingly good development. I'm surprised because it performs so well," says Whisson. And he says the power generating part of the wind turbine can simply be increased to collect the wind power required for the condensation process. "We've got unlimited power," he says. But Reizes says wind turbines are so far only about 30% efficient at best and the energy arriving at them is very diffuse, requiring large devices to collect the energy. "It may be a fantastic idea on paper and it looks as if it could work," he says. "However, the thing may have to be so big to drive this device that it becomes impractical." Drawing moisture from air One thing seems more certain. If the system does work, it is unlikely to backfire on the environment, says Dr Michael Coughlan, of Australia's Bureau of Meteorology. He says the amount of water that humans would use is trivial compared with the amount available in the atmosphere. "If you can tap into it, then go for it, because you would do little to upset the hydrological cycle," says Coughlan.
17/10/07 Wave farm could soon make a splash
Anna Salleh ABC Online
Commercial wave-powered water desalination and electricity generation is one step closer to reality, report Australian developers.
Trials of a technology called CETO have yielded promising results, says Dr Michael Ottaviano of Carnegie Corporation, which is developing the system in the southern hemisphere.
The tests, carried out in Fremantle, Western Australia, verify predictions of how much electricity and water the technology can produce under various wave conditions.
"We've found a perfect correlation between the results our models predicted and what we've actually measured in the ocean, which is a major technical milestone," says Ottaviano.
The CETO technology, first conceived by Perth-based inventor Alan Burns in 1975, consists of submerged buoys connected to seawater pumps fixed to the seabed.
12/10/2007- Solar takes off with US power supply deal
By Matt Peacock
David Mills says solar power could potentially supply most of the world's electricity (File photo). (ABC Central Victoria: Terri-Anne Kingsley)
Video: Aust technology to revolutionise clean electricity (ABC News)
Video: Extended interview with Dr David Mills (7.30 Report)
Two of America's biggest power utilities have unveiled plans for a multi-billion-dollar expansion of solar power supply, backing the argument that solar energy can indeed become a viable alternative to coal-fired electricity.
The company at the heart of the development is Ausra. It was started by Australian solar expert David Mills, who left this country for California earlier this year to pursue the further development of his ground-breaking work.
What makes the announcement more significant is that the utilities are confidently predicting that their solar power will soon be providing baseload electricity - that is, day and night - at prices competitive with coal.
8/10/07 - Melbourne, Australia: Solar Systems Announces A$32 million Investment in Solar Manufacturing
Melbourne based, Solar Systems is to invest in two facilities: a high-tech solar manufacturing plant in Melbourne and a regional large scale Research and Development facility. Solar Systems has developed high performance solar power station technology over the last 16 years and is now gearing up to install large scale, grid connected power stations.
Solar Systems’ new headquarters and photovoltaic module manufacturing facility will have an annual capacity of 300MW of photovoltaic modules (at 500x concentration). Operation of the new facility will commence in the first quarter of 2009.
“This is another major step towards affordable mainstream solar power,” said Dave Holland, Managing Director. “The $22 million facility will be located in metropolitan Melbourne and will directly employ approximately 150 people. Instead of making traditional PV modules, the factory will produce modules specifically for Solar Systems’ solar concentrator systems. Solar Systems’ PV modules produce 1500 times more electricity per square meter than traditional PV modules."
“The modules will initially be deployed by Solar Systems in a number of power stations across Australia including the $420 million North West Victorian power station announced late last year with the support of the Australian and Victorian Governments, and a number of projects in international markets."Further details about: Solar Systems
17/9/07 - 'Green roofs' could cool warming cities
NewScientist.com news service -Catherine Brahic
Covering city buildings in vegetation – creating “green roofs” and walls – could substantially save energy by reducing the need for air conditioning on hot days, say researchers.
Green roofs and walls can cool local temperatures by between 3.6°C and 11.3°C, depending on the city, suggests their new study.
Eleftheria Alexandri and Phil Jones at the Welsh School of Architecture, at the University of Cardiff in the UK, mimicked the microclimate around and inside buildings using computer modelling. They compared local temperatures when buildings were made of bare concrete with when the concrete was covered in vegetation.
Such green surfaces are already in use – roofs that are strong enough to take the additional load can be covered with mosses, turf and even trees. In Switzerland, roofs covered in alpine plants that require little soil are becoming increasingly common. Walls can also be greened, often by climbing plants planted at ground level.
Temperature drop
The researchers compared the effects of green surfaces in nine cities around the world, including subarctic Montreal in Canada, temperate London in the UK, humid Mumbai (India), and tropical Brasília (Brazil). In all cases, they studied the month during which that city sees its hottest temperatures.
They found that green walls and roofs would cool the local climate around a building in all of the cities – and the hotter the climate, the greater the cooling effect.
If, for example, a group of buildings in Riyadh, Saudi Arabia, is entirely clad in vegetation, the gap between the buildings will become 9.1°C cooler during the day, according to the researchers' model. The gap's peak temperature of the day is brought down by 11.3°C. And in London and Montreal, the peak temperature drops by just over 4°C.
Greening the walls only, and not the roofs, results in smaller effects. Maximum temperatures in London and Montreal, for example, drop by between 2.5°C and just over 3°C between the buildings.
Green surfaces cool local temperatures in two ways. Firstly, the green surfaces absorb less heat from the sun. Hot surfaces warm the air around them, so by cooling the surface, the vegetation also affects air temperatures. Secondly, the plants also cool the air by evaporating water in a process known as evapotranspiration.
Lowering demand Being dense regions of concrete and paved surfaces, cities and towns lose the cooling effects of vegetation. This generates what is known as the "urban heat island" effect.
Alexandri and Jones say their results suggest the urban heat island effect could be countered by introducing green roofs and walls in cities.
They point out that, other than making cities more comfortable and safer to live in, green roofs could also significantly reduce the demand for electricity – most of which is generated by burning fossil fuels and therefore contributing to man-made global warming.
In recent years, Europe and North America have been hit by severe heatwaves, the effects of which are often most extreme in cities. In 2003, a heatwave in Europe is thought to have killed 35,000 people and hundreds died this summer in Eastern Europe. Research has shown that the frequency of extremely hot days has nearly tripled in Europe since 1880. Eliminating air-con< "In addition to the fact that they add a further insulation layer to the building, the green surfaces can decrease air conditioning demands inside the building," says Jones.
In Brasília and Hong Kong, he and Alexandri found that the need to air-condition a building during the hottest month of the year is eliminated if it is given a green roof and green walls. Buildings in these cities would normally need air conditioning in the afternoon and early evening.
In hotter cities, such as Riyadh, the number of hours when air conditioning is needed would be cut from 12 hours to just 5.
Some air conditioners still use chemicals that deplete the ozone layer and demand for air-conditioners is expected to rise as a result of global warming, so green buildings could help counter this demand. Journal reference: Building and Environment (DOI: 10.1016/j.buildenv.2006.10.055)
7/9/2007 - Car makers focus on fuel efficiency at auto show
Car makers will show off their latest efforts to fight pollution at Frankfurt's auto show next week, by unveiling models with improvements rather than substitutes to the standard internal combustion engine.Under pressure to reduce harmful emissions produced by their vehicles amid fears of global warming, they are keen to show the greenest of intentions with the latest line of engines that consume fuel more efficiently.
For anything more advanced like a hybrid engine, PSA Peugeot Citroen, Mercedes Benz and others will need another two years before they can show anything worthy of the road, far behind their Japanese rivals.
Toyota, whose Prius hybrid car has been on the market for 10 years, is announcing a partnership with French power utility EDF to set up a network of plug-in points where hybrids can recharge their batteries.
Commercial wave-powered water desalination and electricity generation is one step closer to reality, report Australian developers.