Monthly Archives: July 2011

Dubai toilets go solar

Dubai Municipality hopes to save up to 100.000 dollars in electricity bills every year and increase environmental awareness by switching to solar power for its 80 public toilets.

Dubai, one of the cities in the United Arab Emirates, which is already developing Masdar, a solar-powered city in the desert —is also pursuing more down-to-earth clean energy applications. About 80 public toilets across Dubai run on electricity, including the fluorescent lights, exhaust fans and small water pumps. This power source will be replaced by solar power in the experimental toilets, says Juma Khalifa Al Fuqae, director of the general maintenance department who is in charge of the project.

Seeing how the sun is always blazing in Dubai all the time, solar-powered structures are definitely a step in the right direction. If these new toilets are successful, Dubai will also be upgrading its older toilets to take advantage of this renewable energy source as well. The city will also be drawing up plans for solar-powered swimming pools and abattoirs for the future.

Mr Al Fuqae says he hopes the initial investment will be returned within two years.

The toilets will be free for public use.


Paint ’em white

In last months’ Newsweek former US president Clinton writes down a dozen ideas on how to attack the job crisis. On of his suggestions doubles as one of the most affordable weapons against climate change: painting your roof white.

There are millions of houses and buildings with tar roofs in the US, which absorb huge amounts of heat when it’s hot. Relying on the centuries-old principle that white objects absorb less heat than dark ones, white reflects the energy away from a building, helping to keep it cool. Painting black tar roofs with a white, solar-reflective coating is a low cost, quick and tangible way to save millions of dollars in energy costs and curb climate change. If you’ve got a bit more money to spend, it turns out that placing solar panels on your roof, can do the trick too; research, published recently in Solar Energy, suggests that daytime ceiling temperatures under rooftop solar photovoltaic systems are lower than under exposed rooftops. So installing solar panels on rooftops helps lessening carbon emissions, and it appears that we actually reduce energy needs at the same time.

But back to the white: studies show that white roofs reduce air-conditioning costs by 20 percent or more in hot, sunny weather. A roof covered with solar-reflective white paint reflects up to 90% of sunlight as opposed to the 20% reflected by a traditional black roof. On a 90°F day, a black roof can be up to 180°F. That heat has a major impact on interior building temperature, potentially heating your room to between 115 – 125°F. A white roof stays a cool 100°F. Plus the inside of the building stays cooler than the air outdoors, around 80°F in this example, reducing cooling costs. What is more, a white roof can cost as little as 15 percent more than its dark counterpart, depending on the materials used, while slashing electricity bills.

Clinton writes that in most of these places you could recover the cost of the paint and the labor in a week.


New technique can harvest energy from the air

Scientists at the Georgia Institute of Technology have discovered a way to capture and harness energy transmitted by radio and television transmitters, cellphone networks and satellite systems. A presentation on this energy scavenging technology was given July 6 at the IEEE Antennas and Propagation Symposium in Spokane, Washington.

The researchers say scavenging the ambient energy all around us could provide a new way to power networks of wireless sensors, microprocessors and communications chips. Manos Tentzeris, a professor in the Georgia Tech School of Electrical and Computer Engineering, and his team used inkjet printing technology to combine sensors, antennas and energy scavenging capabilities on paper or flexible polymers. Presently, the team’s scavenging technology can take advantage of frequencies from FM radio to radar, a range of 100 Mhz to 15 GHz or higher. The devices capture this energy, convert it from AC to DC, and then store it in capacitors and batteries.

“There is a large amount of electromagnetic energy all around us, but nobody has been able to tap into it,” said Manos Tentzeris, a professor in the School of Electrical and Computer Engineering. “We are using an ultra-wideband antenna that lets us exploit a variety of signals in different frequency ranges, giving us greatly increased power-gathering capability.”

The researchers have already successfully operated a temperature sensor using electromagnetic energy captured from a television station that was half a kilometer distant. They are preparing another demonstration in which a microprocessor-based microcontroller would be activated simply by holding it in the air.

The researchers believe that self-powered, wireless paper-based sensors will soon be widely available at very low cost and could be used for a variety of purposes.

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