Monthly Archives: April 2011

Paris sewers turned into renewable heat source

A pilot project in the french capital is using sewage waste-water heat to warm a nearby primary school and in a later stage, along with others, the Presidential palace. The city of Paris wants green sources to fuel 30% of its energy needs by 2020. The new heating project, which is a collaboration between the city’s water department and two other companies, is the city’s first using power from the sewers.

The energy that goes into heating water for dishwashers, washing machines, showers and sinks usually goes to waste, but now it will be recovered. A steel plate is installed in the pipes where the sewage flows fast enough to maintain a constant temperature. The steel plate comes in contact with the waste-water and has a series of pipes through which a coolant ciruclates. The fluid is directed to a heat pump that concentrates the heat as high a temperature as 60 degrees Celsius.That heat is transmitted through the school’s HVAC system, which will heat the rooms.

The harnessed heat can only be used within 200 metres (656 ft) of its source – making it impractical for city districts lying far away from the sewage network. This means in theory 10% of Paris could be heated in this manner. The city plans to implement the system in additional schools, government buildings, and eventually; the Élysée Palace – the Presidential home.

The technique requires no combustion and it’s said that only the heat is recovered from the sewer water, not the smell.

Read more: The Montreal Gazette

Turning windows into solar panels by using photovoltaic cells

Massachusetts Institute of Technology researchers have developed a a new class of transparent photovoltaic cells that can turn an ordinary windowpane into a solar panel. Windows could therefor be turned into mini-power plants capable of producing enough electricity to run appliances in the building.

The researchers were able to develop a specific chemical formula for their cells that is based on organic molecules. When these cells are combined with partially infrared-reflective coating of indium-tin oxide it gives both high visible-light transparency and better efficiency than previous attempts on a transparent solar cell. The transparent PV system could be coated on the inner surfaces where it would be protected from window washing or the weather.

Richard Lunt, a postdoctoral researcher at MIT’s Research Laboratory of Electronics, says the new photovoltaic cells have the potential to turn skyscrapers into enormous solar collectors that could supply much of the electricity needed in modern office buildings.

The largest challenge in developing commercial applications for the new solar cells will be longevity. The photovoltaic cells that would have to last as long as the windows themselves, since the best way to use the cells would be to package them in the middle of double-pane windows.

For more info, see:

Sustainable energy in Kenya’s slums

In the impoverished Nairobi neighborhood of Kibera an innovative program is not only helping to solve sanitation problems in the area, but also turning the problem into a green energy solution.

The high, and rising cost of fuel – kerosene, paraffin, charcoal, firewood – eats up a large perecentage of the household income of the poor living in the slums. The use of polluting energy sources in closed spaces is another charge against the health of the people, the wider environmental implications of fossil fuels or inefficiently burned biomass completes a glum accounting. At the Katwekera Tosha Bio Centre, set up with the help of the Umande Trust, however, Kibera residents can safely and cheaply cook food using biogas generated from the center’s toilets.

The centre has toilets and bathrooms on the ground floor — the toilets are connected to a bio-digester, with a dome-shaped holding tank in which biogas is produced. Raw human waste from the toilets flows in, and bacteria break it down, releasing methane gas which collects at the top of the domed tank. “A pipe is then plumbed into these toilets and connected to the first floor, which is where the cooking area is located,” says [center manager David] Kihara. The gas is piped to collective stoves one floor up — and is usually sufficient for community members to cook on throughout the day.

From a business perspective this biocentre is also interesting. Katwekera makes a profit of between 250 and 450 euro’s a month, this money is being re-invested in the centre.

For more info see

Coal Use Criticized by IEA as Energy Leaders convene

The latest report of the International Energy Agency, called the Clean Energy Progress Report, warns that coal and gas support could make 2050 climate targets an impossibility.

The report shows that since 1990 renewable energy as a whole has grown 2.7% per year, but electrical generation as a whole has grown by 3%–with just almost 50 % of that coming from coal since the turn of the century. In 2009 renewables got $57 billion in government support, while fossil fuels received $312 billion. The report is urging governments to boost incentives for clean power.

Last Thursday government energy leaders from major consuming countries met in Abu Dabi. The IEA recommended legislators should phase out fossil fuel subsidies, promote biofuels and boost support for renewable energy, carbon capture and energy efficient buildings.

On a more positive note, the report does point to encouraging growth over the past decade in both solar power (10 countries now have sizeable domestic solar power markets) and wind power (a ten-fold growth in installation).

For more info, see the full report:

New fast recharge battery for electric cars

One of the problems with powering electric cars lies in the fact that batteries take up to eight hours to charge. Now a new type of lithium-ion battery, that features a 3-D interior structure, is able to recharge in just a few minutes. This could bring closer the day in which electric cars can recharge as quickly as gas-powered vehicles fill their tanks at the pump.

Lithium-ion batteries are the most popular devices for powering electric cars and portable electronic gadgets thanks to their high energy density and low weight. Existing Li-ion batteries recharge slowly, last only about two years, and need special integrated circuits to avoid overheating.

The 3-D Li-On battery prototype was developed by researchers at Colorado State University and presented at this week’s national meeting of the American Chemical Society. Study leader Amy Prieto says the 3-D prototype has about the size of a cell phone battery and takes about 12 minutes to recharge, compared to two hours for a conventional lithium-ion battery. It’s also said to have double the lifespan. The battery can be discharged over twice as many times as a conventional lithium ion battery at high discharge rates, she added.

Prieto used nanowires of copper antimonide instead of the graphite anode. They are more stable and heat resistant than the graphite electrodes used in existing batteries.