Click on the headline (link) for the full text.
Many more articles are available through the Energy Bulletin homepage
Lime is a much greener option than cement
Douglas Kent, The Guardian
Carbon emissions could be cut if we used this ancient building material more widely.
—
As David Adam reports (The unheralded polluter: cement industry comes clean on its impact, October 12), cement production now accounts for 5% of mankind’s emissions of CO2 – and the projected rapid expansion of the sector means this figure will rise. Despite this, as the Cement Sustainability Initiative’s Howard Klee says, “Most people are not even aware that making cement produces carbon dioxide.”
The good news is that cement producers now appear to be acknowledging that they make a major contribution to greenhouse-gas emissions and are beginning to take steps to reduce their environmental impact. But as Adam writes, their efforts, such as burning waste products with coal, reworking recipes and trying to make plants more energy-efficient, have achieved only “modest success”.
Dimitri Papalexopoulos, managing director of Titan Cement in Athens, is right to say that producers of cement “can’t change the chemistry, so we can’t achieve spectacular cuts in emissions”. However, he is wrong to assert that “there is no obvious substitute”. Another product, lime, has the potential to play an important role in carbon reduction.
Lime has been used for building for 10,000 years, whereas Portland cement was only patented in 1824. The Pantheon in Rome has a lime concrete dome spanning over 43 metres that has survived for nearly 1,900 years, and countless old buildings in Britain were built with lime mortar, including much of the 20% of our housing stock that predates 1914.
The use of lime declined in favour of Portland cement during the late 19th and early 20th centuries. Cement sets faster and demands less skill in its application. Over the past 20 years, though, lime has enjoyed a revival after the harm caused to old buildings by cement became apparent. More recently, although the science of using lime concrete for engineered reinforced structures with large spans has yet to be developed, interest in the use of lime for new construction has grown as a result of its ecological credentials.
Lime requires less energy to produce than cement because limestone, the basic raw material, can be burned at lower temperatures – 900-1,000C rather than 1,300C or higher. Also, some of the CO2 created during firing is reabsorbed by lime as it hardens. And lime can be produced locally on a small scale, cutting pollution by limiting transport distances.
(23 October 2007)
Could Electricity Grid Become A Type Of Internet?
Science Daily
In the future everyone who is connected to the electricity grid will be able to upload and download packages of electricity to and from this network. At least, that is one of the transformations the electricity grid could undergo.
Dutch researcher Jos Meeuwsen (Technical University Eindhoven) developed three scenarios for the Dutch electricity supply in the year 2050. The starting point is that in this year, 50% of the consumption will originate from sustainable sources.
Due to the security of supply and the connection with the European market, electricity networks will always be necessary says Meeuwsen. Further, due to an increasing demand for electricity it is important to include all possible energy options (including coal and nuclear energy) in the scenario development. …
Adapted from materials provided by Netherlands Organization for Scientific Research.
(25 October 2007)
GE hopes to cut mercury in “green” light bulbs
Timothy Gardner, Reuters
General Electric Co is working to cut the amount of mercury in energy-saving fluorescent lightbulbs which have soared in popularity.
Residents and businesses are buying up compact fluorescent lightbulbs (CFLs) because they reduce power bills as well as emissions of carbon dioxide, the main gas blamed for global warming. CFLs use only one-fourth to one-fifth the energy of incandescent bulbs producing the same light and can last 10 years.
The corkscrew-shaped devices are made by many companies and on average contain about 5 milligrams of mercury, a toxic metallic element, according to the Environmental Protection Agency.
Five milligrams is tiny amount, about the size of the tip of a ballpoint pen, and much less than the amount that was held in old thermometers. But with sales of CFLs hitting 150 million units last year, and more expected this year, some scientists and environmentalists are worried that most of the bulbs are ending up in landfills instead of being recycled.
(24 October 2007)
The rush to CFLs has ignored this toxic side-effect. -BA
