A substance that literally forms the foundations of urban living, concrete is indispensable to the way we live. Unfortunately, it is yet another example of a greenhouse gas emitting, unsustainable practice. In the era of climate change where our actions are subject to constant scrutiny, we cannot ignore the impacts of the cement industry. Enter green cement, the attempt by industry to enhance sustainability and reduce emissions.
Of global CO2 emissions, 5% come from the cement industry. The main ingredient in concrete, limestone, is a mining intensive resource that emits high emissions during manufacture. Greenhouse gas emissions come from the fuel utilised to heat limestone, and from the subsequent chemical reactions. At an extraordinarily cheap 15 cents per kg, we are not paying the true environmental or social cost of cement. (image: olovedog)
The future of green cement
Eco-cement is a ‘watered down’ version of conventional concrete, whereby waste materials are added to the mix. For some years now companies have been ‘blending’ cement with waste products from coal-fired power plants and iron manufacturing. Reducing the amount of limestone cuts energy costs and emissions. The result is a cheaper, lower carbon cement. Besides waste ‘blended’ cement, there are several other initiatives pushing the industry forward.
Companies such as LaFarge have produced an ‘aether’ cement that reduces emissions from 30% to 50%. Simply by changing the proportions of existing raw materials, the energy manufacturing needs have been cut dramatically.
Work is also being done to create a new cement which replaces energy intensive limestone with an alumino-silicate base. By switching raw materials, emissions from manufacturing can be curbed by 60%. Geopolymer cement is already commercially available.
Novocem is taking it even further. The company claim to be developing a carbon negative cement. This exciting new technology is able to absorb up to 100kg of CO2 per tonne. This cement is still very much in the experimental phase, but Novocem hopes to be producing 25,000 tonnes a year by 2015.
How can we support green cement?
The most obvious way we can support green cement is to increase consumer demand. Consumer reluctance is the key issue standing in the way of success. Companies are wary to invest in a product that has not yet stood the test of time. No-one wants to be the first to try out new technology. If enough companies and individuals phase low carbon cement into their building materials, it should strengthen confidence in the long term.
Don’t wait for the technology – act now
As the technology develops, here are some steps you can take in the now:
- Use only what you need. There are options besides concrete for foundations, such as tires or rocks
- Request low emission eco-cement where plausible
- Even better, ask for carbon zero cement. Companies such as Ecocem in Ireland have been providing a carbon-zero cement since 2003. A combination of waste inputs and carbon offsets has allowed them to achieve this status
Insipid yet integral to our lifestyles, it is time to stop ignoring the impacts of concrete manufacture. The cement industry will play a big role in emissions reductions in the years to come. With the improvements in technology, there are many ways to support the development of green cement. Perhaps Amory Lovins of the Rocky Mountain Institute sums it up best by saying that green technology “will happen, and happen rapidly– because it’s profitable.”
the current practice of using cementitious additives does very little to actually reduce the CO2 emissions from cement and unfortunately HAS to be considered one of the greatest examples of green washing currently on the market.Reply
the processes involved in creating these “waste” products are equally damaging. iron ore smelting process simply heats limestone to 1400deg instead of 1800deg for cement production. many of the CO2 claims are based upon these “waste” products being zero rated for emissions. because the feedstock mix is now being specifically being tailored for the waste to be used as a cementitious additive the EU now no longer considers them waste and should be termed by-products (nobody would consider cream a waste product of skimmed milk production)
however we look at (or indeed the cement industry looks at it ) adding high energy and high emission by-products to cement does not solve or reduce the problem and absolutely does not warrant the title of green cement.
also the produced amounts of these by-products is so low in countries like the uk that we can never supply enough without resorting to imports from large steel producing countries.
my concern is that the marketing of such products is actually spearheading an attempt to increase the use of cement and concrete on the basis that it is now “green”
high energy and emission materials will never be part of the solution. reduction in their impacts is a benefit but elimination of their use HAS except in absolutely necessary applications must be the longer term goal. in spite of these developments cement related CO2 emissions continue to rise even during a worldwide downturn in construction.
if anyone requires more detailed info this was actually part of my masters thesis and I can supply referenced data if necessary