Cement, the ubiquitous cementitious material that makes concrete buildings, roads, sidewalks, sewers and all the invisible gray parts of infrastructure possible, is formed by heating limestone and other materials to 1450 degrees Celsius in huge rotary kilns, where limestone is broken down into lime and carbon dioxide. The lime forms a cement powder, and the carbon dioxide-38% by weight of the limestone-goes into the exhaust funnel. By burning coal or oil to produce extremely high temperatures to carry out this necessary chemical reaction, greenhouse gases are produced as a by-product.
For every ton of cement produced, 3/4 tons of carbon are emitted into the atmosphere, and the carbon emissions of the whole cement industry account for 8% of the global total. This inevitable cement byproduct and the government's actions on climate issues are combining to make the cement industry face an existential crisis. It has also spurred a revival of alternative materials to concrete.
Canadian Prime Minister Justin Trudeau and several provincial premiers met last week to discuss national climate change policy. Ottawa's top priority is to establish a domestic minimum carbon price, either through a carbon tax (currently being implemented in British Columbia) or tradable carbon permits (being explored in Quebec, Ontario, and Manitoba). Either way, cement will become more expensive.
& emsp; & emsp; "We believe that carbon must have a price," said Martin Vroegh, director of environmental affairs at St Mary's Cement, during a tour of his company's namesake plant. "But we have to be able to pass on the price to the consumer, otherwise the industry will not survive. It's as simple as that." In economic terms, the cement industry is a "high energy consumption, complete competition" industry. It emits a lot of carbon, and it faces a lot of competition from other countries, such as the United States, that have not made the same climate change commitments as Canada.
A carbon price above $100 a tonne-the minimum required to meet Canada's commitments at last year's climate change conference-would increase the cost of cement in Canada by a third, threatening the survival of producers such as St Mary's Cement. The current carbon tax in British Columbia is $30/ton, which led to a surge in overseas cement import sales last year. Chris Ragan, an economist at McGill University and a member of the Canadian Carbon Pricing think-tank, acknowledges that the cement industry, along with other trading industries, will probably need to be sheltered by foreign companies that do not have a carbon price. This could take the form of a cash transaction, as in British Columbia, or a limited supply of free carbon permits under an emissions trading scheme. But Ragan says any government protection must be temporary if Canada is to transition to a low-carbon economy. "In the long run, the cement industry will either change the way it produces cement or look for building materials to replace cement because it becomes too expensive."
Canadian cement producers have implemented various ways to reduce carbon emissions. A new cement formulation reduces the burning of limestone by 12%, resulting in lower emissions. There are also emissions reductions through alternative fuels such as waste wood, shopping bags and other debris. Maybe even convert it into something useful like growing algae and plants by filtering all the CO2 and waste heat.
Perhaps the cement industry's biggest threat comes from its old rival, with building standards in some provinces now allowing timber frames for buildings of up to six storeys. Timber is the first choice for some government-funded projects, which increases the demand for timber. Using wood instead of choosing to emit carbon is good for climate change. The result has been a recent boom in wood-frame construction for family homes. Since British Columbia changed its rules in 2009, more than 250 mid- and high-rise wood-frame buildings have been completed, are underway, or are planned.
& emsp; & emsp; "Until building standards change, steel or concrete is the only way to go," says Vancouver developer Dana Westermark. "Wood makes the most sense now." A mid-rise timber building is 30% cheaper than a concrete structure and 15% cheaper than a steel structure. "You can build in any weather, the wood structure is lighter and easier to obtain, and the carbon tax makes the wood structure more advantageous."
Faced with the loss of important markets, the cement, concrete and steel industries are fighting back with their strongest attribute: fire resistance. "Didn't you put your mother in the woodpile?" Vroegh said. And the print ads of the Concrete Block Association also hit back, "Muxian?"? Die first. "On the side is a picture of Atlanta burning.". An experiment by a developer in a federal government laboratory showed that a three-story wooden mock-up could withstand at least two hours of intense heat. "There is no significant difference in safety, stability and acoustic properties between concrete and wooden structures," said Fr Frédéric Verreault, a spokesman for the developer. However, he also acknowledged that inorganic materials such as concrete have their place in wooden buildings, such as concrete underground parking garages.
浙公网安备33010802003254号