The U.S. government's Climate Change Science Program issued a report in August 2008 in which it confirms that the warming our climate has experienced in the last few decades is the result of human activity. This is not the first time that "human activity" has been identified as the cause of climate change. Indeed, it is a well established fact that our consumption of oil and other fossil fuels has raised the level of CO2 in our atmosphere to levels not seen before in our civilisations history.
Instead of describing the problem as "human activity" we could probably more accurately define it as our insatiable and ever increasing need for energy. So, with the problem so clearly identified you may wonder why we haven't been busy developing a whole series of new and innovative technologies to combat the threat. Well, believe it or not, we have. As reported many times on Celsias, new ways of capturing solar wind and geothermal energy are constantly being found, and now a group of U.S. researchers may have found the most original solution yet.
A research group at Worcester Polytechnic Institute (WPI) has been investigating a novel way to harvest solar energy from roads and parking lots. Headed by Dr. Rajib Mallick, the group believe it may be viable to place solar collectors beneath roads and other asphalt covered areas to collect the huge amounts of heat already captured by these surfaces and convert it into energy.
"Asphalt has a lot of advantages as a solar collector," Mallick says. When the sun goes down it stays hot for significantly longer than traditional solar collectors and could continue to generate power. Roads and other asphalt covered surfaces already account for a huge amount of real estate in the U.S. and, ironically, in most of the energy guzzling nations around the world. These could be converted to produce energy, reducing the land required for solar power generation.
Extracting heat from asphalt will cool it, and may reduce the "heat island" effect noticed in many cities. And unlike rooftop solar panels, solar collectors in roads would be hidden. Mallick suggests that solar collectors could be fitted into roads while they are being resurfaced, a process usually done every 10-12 years.
The research began at the behest of Michael Hulen of Novotech Inc. a company specialising in infra-red optical and semiconductor materials, which already holds a patent on the concept of using heat absorbed by pavements. The team began studying the heat absorbing properties of asphalt in the lab using computer models. Then small slabs of the material, fitted with thermocouples to measure heat penetration and copper water pipes to measure heat conduction efficiency, were exposed to halogen lamps to simulate sunlight.
The tests then moved outside where larger slabs of asphalt were exposed to direct sunlight, wind and rain for more realistic measurements. All the tests showed that asphalt absorbed a significant amount of heat with the highest temperatures recorded a few centimetres below the surface. The researchers found that adding materials that were highly conductive to heat, such as quartzite, significantly increased the heat absorbent properties of the asphalt. They have also conducted experiments with special paints to reduce the reflective properties of the asphalt and cause it to absorb even more solar radiation.
Dr. Mallick believes that the key to turning asphalt into a successful energy generation system is to use a highly conductive heat exchanger. "Our preliminary results provide a promising proof of concept," he says. On August 18, 2008 his fellow team member, Bao-Liang Chen, presented their findings to the annual symposium of the International Society for Asphalt Pavements in Zurich, Switzerland. It's hoped that by using this research, a way can be found to transform the huge areas of land already covered in asphalt into a renewable energy source.
Further Reading:
- World Geothermal Power Generation Nearing Eruption
- The Coming Energy Shift - Update
- Polar Explorer Raises the World's First Solar Sail
- Geothermal Energy: Google puts $10 Million Into New Technology
- Geothermal Energy - Could Power The US For 30,000 Years
- Concentrating Solar - Now Safe For Roof Tops
- U.S. Takes the Lead in Wind Energy Generation
- Will Africa Be The Hub For a Green, Global "Super Energy Grid"?
- Nature Inspires Solar Power Revolution
- Wind Power From Kites
- Solar Powered Car Arrives on the West Coast to Take in the Sun and Spread Renewable Technology Gospel
- The Wave of the Future? Harnessing the Oceans' Energy
- Utah's Solar Fired Furnace to Power California for Less Than the Cost of Coal or Gas
- Solar Thermal Power Coming to a Boil
- First Solar to Build 10-Megawatt Photovoltaic Power Station
- Nanosolar Cheaper Than Coal
- Thin Film Solar Now Shipping
Solar Roads is not a new idea by any means: see www.solarroadways.com. While the asphalt research presented here is very clever, one thing has been overlooked: the rising price of our petroleum-based asphalt. Liquid asphalt was $175/ton last December. By June it was $480/ton. By July, bids were coming in at over $1000/ton. The federal and state transportation departments are broke and operating in the red.
Some areas can't even get the asphalt that they've secured the funding for: see the article at http://seattletimes.nwsource.com/html/localnews/2008080652_asphalt30.html
The days of surfacing roads with asphalt are quickly coming to an end. I've spoken with the U.S. Department of Transportation and some state transportation department heads. They all see the writing on the wall and are looking for new materials to replace asphalt with.
Written in August 2008