© Fraunhofer Institute for Building Physics
A process for disintegrating waste concrete into its various components using bolts of lightning could help to make concrete a truly recyclable building material.
When it’s recycled at all, waste concrete is typically ground down into smaller pieces, a process that not only produces lots of dust, but because of its limited efficiency, turns out a product mostly used as a road base material. That process is more akin to simple reuse than to true recycling, and it only accounts for a small percentage of the waste concrete produced every year.
But if there was a process that could break down the concrete into its constituent components, which could then be used again in new products, then the rate for waste concrete recycling could jump by a factor of ten, according to research being done in Germany.
Researchers at the Fraunhofer Institute for Building Physics IBP are using a process known as electrodynamic fragmentation to selectively separate concrete in their lab. The method was originally developed by Russian scientists in the 40s, but it wasn’t until recently that the technology was improved to the level that could make large-scale use feasible.
The fragmentation system, also known as “pulsed power processing”, uses electrical pulses forced through the materials, which are submerged underwater:
“When the pulses strike the rock, in this case the concrete, the pre-discharges always follow the path of least resistance – along grain boundaries.” – Dr. Volker Thome
Once the pre-discharges have weakened the rock along its grain boundaries, shock waves then disintegrate the concrete by pulling it apart into its individual components with great force:
“The force of this shock wave is comparable to that of a TNT explosion.” – Thome
Once the components have been dried and screened, they can potentially be reused as raw materials, such as gravel aggregate in cement production. With the hundreds of millions of pounds of waste concrete generated around the world each year, being able to recycle even some of it would reduce not only the need for new mineral extractions, but would also lessen the loads of landfills.
Mining companies currently use the fragmentation process to separate valuable minerals from the surrounding rock without destroying them, and this new advancement could also be developed into applications for recycling carbon fiber reinforced polymers and reclaiming municipal solid waste incineration (MSWI) bottom ash, according to the researchers.
Scientists in the United Kingdom recently completed a study suggesting that Arabica coffee, the species that makes up 75 percent of coffee beans sold, could become extinct in 70 years. Due to climate change and its symptoms including deforestation, at team at the Kew Royal Botanic Gardens ran a series of computer simulations that indicate that wild Arabica coffee could become extinct by 2080.
Such a development should worry everyone from growers to consumers. Coffee is the second most traded global commodity after petroleum and is an economic lifeline for many countries in Africa and Latin America. Since the Arabica coffee beans grown throughout the world’s coffee farms are from a limited genetic stock, they are susceptible to pests and diseases. Wild Arabica coffee stock offers opportunities for scientists to extract some of its genetic stock to strengthen cultivated varieties and make them more climate change resistant.
The Kew scientists ran a series of analyses to gauge the future of Arabica coffee production in a world affected by climate change. The results showed that by 2080, the most favorable outcome would be that the world would suffer a 38 percent reduction in land suitable for coffee production–but the worst case scenario was a 99.7 percent reduction, which would effectively wipe out wild Arabica plants.
The team then traveled to the Boma Plateau region in South Sudan, a region where coffee cultivation has endured for centuries. The area had already undergone dramatic change, from deforestation to land clearing for agriculture. Compared to earlier studies, the Boma Plateau had suffered environmental degradation, with reduced seedlings, a lower frequency of flowering and fruiting and finally, a decrease in mature pants. Add the fact that coffee has risen in price in recent years because of poor harvests yet continued increased demand, and the long term prospects for coffee could become very grim.
Kew’s scientists hope their study is a clarion call for an increased understanding of coffee’s precarious future. The research team identified a series of sites in eastern Africa that could become home to wild coffee plants. And while deforestation has had a role in decreased coffee yields, climate change alone could be the deciding factor in Arabica beans’ survival. To that end, the Kew study calls for more storage of varieties in seed banks and immediate conservation action. Despite all the actions of fair trade organizations and groups including the Rain Forest Alliance, larger forces could have a huge impact on coffee cultivation in the years to come. Coffee companies will have to step it up if their businesses are to survive in the long term.
Leon Kaye, based in Fresno, California, is a sustainability consultant and the editor of GreenGoPost.com. He also contributes to Guardian Sustainable Business, Inhabitat and Earth911. You can follow Leon and ask him questions on Twitter.
Sail-inspired turbine promises cheaper wind energy
5 November 2012 | EN
[TUNIS] A Tunisian invention that harvests wind energy through adesign inspired by sailboats promises cheaper, more efficient wind energy.
The bladeless wind turbine, the Saphonian, named after the wind divinity that was worshipped by the ancient Carthaginians, also promises to be more environmentally friendly than existing wind turbines that produce noise and kill birds through their blade rotation.
Instead of rotating blades, the Saphonian’s sail-shaped body collects the kinetic energy of the wind, Anis Aouini, the Saphonian’s inventor, told SciDev.Net.
He explained that the resulting mechanical energy moves pistons which generate hydraulic pressure that can be stored in a hydraulic accumulator or converted into electricity.
“This is not the first bladeless wind turbine, but we thought outside the box: the initial idea came from sails — the only human system that can capture and convert the bulk of the wind’s power into mechanical energy,” said Aouini.
An average wind turbine captures only 30 to 40 per cent of the wind’s kinetic energy, while the Saphonian can capture up to 80 per cent, according to Aouini.
Hassine Labaied, chief executive of Saphon Energy, the start-up energy company established to get the turbine to market, said the Saphonian reduces the aerodynamic and mechanical energy losses associated with rotating-blade turbines.
“Our second generation prototype is 2.3 times more efficient, and costs nearly half the price of its predecessors [conventional wind turbines]. It discards the most expensive components in a traditional wind turbine, which are the blades, hub and gearbox,” said Labaied.
Aouini and Labaied patented the technology in Tunisia in September 2010, and received an international patent in March 2012. Saphon Energy is now looking for a partnership with a manufacturer to deploy the technology worldwide.
“We are negotiating with a number of international companies that produce renewable energy technology, and will finalise this by the end of this year,” said Labaied. He estimated that it would take up to two years until the commercial product reaches the market.
Ali Kanzari, a renewable energy expert and director-general of Solar Energy Systems, told SciDev.Net that the Saphonian “seems to be a radical and economically viable alternative to bladed turbines”. However, he added that “the manufacturing step is important as it will determine how the market will accept it”.
“The electricity produced through wind in Tunisia represents five per cent of total electricity production in the country,” Ayadi Ben Aissa, former chief executive of the Tunisian Society of Electricity and Gas (STEG), told SciDev.Net.
He said that using the Saphonian technology could produce up to 20 per cent of Tunisia’s electricity from wind in the medium term.
This is a blog that will be part of a final project for my Environment in Literature class. I will be posting articles on various sustainability and environmental topics and asking people to comment on them in hopes of starting an engaging and informative discussion. Feel free to add your comments to any topics you are interested, and thank you for your help!