Monthly Archives: December 2009

Waste management strategies helps reduce greenhouse gas emissions

A study of Aalborg in Northern Denmark has measured the impact of waste management changes and found that cities can not only control greenhouse gas emissions, but also reverse the effect by producing energy while saving on toxic emissions.

Researchers Tjalfe Poulsen and Jens Aage Hansen from Aalborg University in Denmark that conducted the study, came up with an analysis on the impact created by waste management systems on greenhouse gas emissions. This long term overview was obtained from the historical data of the municipality of Aalborg. The entire study was based on the assessment carried out on organic waste that includes plastic and paper along with food waste, sewage sludge and yard waste.

In 1970 Aalborg’s municipal organic waste management system resulted in net greenhouse gas emissions with methane from landfill accounting for almost 100%. But between 1970 and 2005, the city changed its waste treatment strategy to include yard waste composting, with the city’s remaining organic waste incinerated for combined heat and power production. After the implementation of smarter waste management, emissions dropped by 80 %.

Researchers predict that in the year 2020 improvements will be brought about by increasing the efficiency of the incineration process and anaerobic digestion. Anaerobic indicates the absence of a common electron acceptor such as nitrate, sulfate or oxygen. Anaerobic digestion is the harnessed and contained, naturally occurring process of anaerobic decomposition. Reduction in the usage of energy in wastewater treatment and separating food waste for anaerobic digestion are other factors that are expected to bring about improvements in the year 2020.

Power from dirt

Lebônê Solutions, Inc. is a social enterprise organization working in off-grid energy delivery and lighting technology using cutting edge clean energy technology. This Harvard engineering team is on a very serious mission: creating a new source of power for the more than 500 million people in sub-Saharan Africa who live without access to electricity. They are not searching in the direction of wind or solar energy sources but are working to develop fuel cells made from the bacteria that occur in soil or waste.

This innovative group was founded in 2007 by Aviva Presser Aiden & Hugo Van Vuuren and is named after the African Sotho word for “light stick”.  Their goal is to help end the energy and lighting crisis in Africa by harnessing emerging technologies and adapting them for the African market where currently 74 % of the population live without electricity.  Back in May 2008 six Harvard students (later known as Lebônê), won a $200,000 grant from World Bank at the Lighting Africa 2008 event in Ghana for inventing a way to turn soil into electricity using microbial fuel cells. The microbial fuel cells they developed use soil bacteria to create an electric charge. In the presence of water, such bacteria naturally produce free electrons as a by-product of their metabolic growth. The cells, which are placed in canvas bags filled with dirt and buried in the ground, harness those electrons to create enough current to power LED lights, run a radio and charge mobile phones.

The Lebônê team could provide the batteries to African villages ready-made, but they want villagers to build their own to promote a sense of ownership. They hope that as the technology is refined, each household can make its own battery for a one-time cost of less than $10. According to Lebônê it can be made by people with minimal training.  “People walk an hour or more a day to the local high schools to get their phones charged for two or three days,” explains co-founder van Vuuren, noting that the phones were sources of light as well as communication devices. The batteries are also used to power radios, Mr. Van Vuuren said, as important a medium of communication in Africa as the cellphone.

This past June, Lebônê used a $200,000 grant from the World Bank to launch an 18-month pilot program in Tanzania. They linked 100 fuel cells and found that after being watered, the batteries could generate power for months through a connected circuit board. If the project is successful, Van Vuuren hopes the cells will offer a low-cost answer to rural Africa’s energy needs for years to come.

UK contemplating tax cut electric company cars

Britain is considering cutting the tax on company-owned electric cars to zero percent, a source familiar with the matter told Reuters on Monday, in a bid to stimulate the market for greener vehicles.

Finance minister Alistair Darling could announce the measures in his pre-budget report on Wednesday as the government is keen to boost its environmental credentials and provide positive stimulus to car manufacturers.

Businesses currently pay National Insurance contributions and employees pay income tax, based on the cost of company cars and its CO2 emissions. The range varies from 9 percent for electric cars to 10-35 percent for fossil fuel cars.

“The government is thinking about reducing the rate for electric cars from 9 percent to 0 from 2012,” the source said.

The source said that at the moment there were only about 50 electric company cars out of a fleet of roughly 1.1 million and the hope is such an incentive will encourage businesses to buy more electric cars as companies like Nissan and Renault boost production next year.

Researchers uncover new method in electrification of waste heat

From computer chips to car engines, from cell phones to laptops; they all release excess heat in order to perform at their optimal level. More than half of the energy consumed worldwide is wasted, most of it in the form of this excess heat. According to researchers from the Massachusetts Institute of Technology this waste heat is a great potential source of energy if harvested correctly. They recently uncovered a new method of obtaining electrical power from otherwise wasted heat.

Waste heat refers to heat produced by machines, electrical equipment and industrial processes for which no useful application is found, and is regarded as a waste by-product. The burning of transport fuels is a major contribution to waste heat. When excess heat is released the efficiency of the equipment will decrease below 100 %. When, for instance, the waste heat from a car engine in the winter is being used for the car radiator, the efficiency will increase. In theory the same principal would apply for cell phones and laptops. If this wasted energy is cleverly harnessed and utilized we might not, for instance, have to recharge our phones or computers that often.

There are many different approaches to transfer thermal energy to electricity, these approaches are mostly still in development. Peter Hagelstein, one of the main researchers from MIT, is of the view that the existing solid-state devices that are already available to convert heat into electricity are not very efficient. It is known as high-throughput power. According to Hagelstein it converts heat from a less efficient system  and you get more energy. But it is a larger and a more expensive system in which you get either high efficiency or high throughput. But the MIT team found that by using their new system, it would be possible to get both.

Theoretically a limit is set on the maximum amount of efficiency any device van achieve when converting heat to electricity. This limit is called the Carnot Limit, based on a formula set in the 19th century. Hagelstein found that current devices can only go as far as one tenth of that limit. Hagelstein and collegues claim to have reached an efficiency as high as 40 % of the limit by using their new technology. They say in the future it might be possible to achieve up to 90 %.

The MIT researchers chose to not try upon improving existing devices but to start from scratch designing the ideal thermal-to-electric converter. It’s not entirely clear how the new system works. It involves a single quantum-dot device – a type of semiconductor in which the electrons and holes, which carry the electrical charges in the device, are very tightly confined in all three dimensions. Such devices are still in development and will not appear on the market for a couple of years to come.

Commute Greener!

We all generate carbon emissions when we commute to work.  To find out how much CO2 we  actually release in the atmosphere and how we can reduce  it,  we can use the “Commute Greener”.  This tool  is accessed through a mobile phone or a web site on the internet, enabling the user quickly to see by how much carbon dioxyde emissions are reduced of increased.

A commuter who downloads the apllication “Commute Greener” from the iPhone App Store, for example, can use the mobile telephone to register the methods of transport that are used for commuting to and from work. The computer program calculates how much carbon dioxide is emitted when using different modes to transport, such as the car, train, bus,

Commute Greener has already been launched within the Volvo Group. “Our test have shown that individuals can quickly reduce their carbon dioxide emissions by more than 30 per cent using it “, says Magnus Holmqvist at Volvo IT.

The same tool will now make it possible for 2000 employees within the City of Gothenburg to understand the most efficient and environmentally sound way to commute in any given scenario, and change their commuting habits.