Asphalt energy is heating up - Daily Commercial News

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It works in the relatively benign climate of southern England, butit adds to the road’s cost. And it’s effectiveness hasyet to be proven in the harsher climate of the north.
But there are already offshoots from the original idea.The pavedplayground of a new school in the south of England acts as a solarcollector which heats the fluid in a sub-surface pipe system. Theheat is then piped to a storage bed beneath the building. In thewinter, a valve isolates the collector from the rest of the pipesystem, and the stored heat can then be sent to thebuilding’s hollow-core floors and ceilings.
It works, and has already seen the school through one winterwithout using any auxiliary heating.
The Dutch have taken the idea a step farther, using the parkinglots as collectors to heat buildings in a shopping complex. TheJapanese reversed the idea, and have pumped river water throughembedded pipes to reduce the temperature and heat deformation ofthe pavement.
The concept has finally reached the United States where researchersat the Worcester Polytechnic Institute in Massachusetts, havelab-tested a system that cools pavement while heating the fluid inthe pipe field embedded in it. The fluid can then be used forheating by running it through a heat exchanger, or for powergeneration using a thermal-electric generator.
The leader of the research team, Rajib Mallick, estimates that thesystem will cost between $20 and $50 per square metre installed.
Mallick’s tests show that the greatest heat absorption occursjust a few centimetres below the surface, which has started himexperimenting with asphalt mixes using different aggregates toimprove conductivity. Quartzite is one aggregate material thatshows promise.
There is a potential benefit the system offers that no one has saidmuch about yet:
The immense amount of pavement in modern cities contributessignificantly to the “urban heat island” effect. Greenroofs help counteract that, helping keep the air a bit cooler, andthus reducing the cooling load during the summer. If a lot of urbanpaving were to be done with solar asphalt, collecting solar heatwould keep the pavement cooler, and help reduce the urban airtemperature.
Green roofs combined with solar asphalt working together to helpheat and cool our cities: Another little eureka moment.
Science that works, step by patient step.
Korky Koroluk is an Ottawa-based freelance writer. Send comments toeditor@dailycommercialnews.com
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