The manufacturing of materials such as steel, cement, paper and aluminum has become far more energy efficient than when these processes were first invented but these processes face increasingly limited options to make them significantly more efficient, according to MIT researchers.
For the report: The energy required to produce materials: constraints on energy-intensity improvements, parameters of demand, researchers looked at how materials manufacturing might meet the energy-reduction targets implied by the Intergovernmental Panel on Climate Change, which has suggested a 50 percent reduction in carbon-dioxide emissions by 2050 as a means of avoiding further climate change. Meanwhile, economists have estimated that global demand for materials will simultaneously double.
To asses the possibilities of reaching these two targets, the team - led by graduate student Sahil Sahni and Tim Gutowski, a professor of mechanical engineering at MIT - studied whether manufacturing processes could improve in efficiency by 75 percent. The researchers identified the five most energy-using materials produced, and outlined scenarios in which further energy may be saved in manufacturing.
Researchers drew up an optimistic scenario in which every manufacturing facility adopts the best available technologies. The team disregarded cost - in reality, often a huge barrier to installing energy-efficient processes. Instead, the researchers looked for any solution that may improve energy efficiency by 75 percent - but found they were unable to reach even half of that value.
The team then tried another tactic, looking to reduce energy-intensive processing through wider adoption of recycling; it requires far less energy to recycle a material than it does to manufacture it from scratch. However, they found limits in the supply of recyclable materials, particularly in developing countries that are growing at high rates.
Even in the most aggressive scenario, the team found it was only able to reduce energy use by about 50 percent - far short of its 75 percent goal.
Gutowski says that the targets appear to be "beyond what industry can do by itself." As a result, we may need to make bigger cuts in other sectors, he says.
Total energy consumption in the manufacturing sector decreased by 17 percent from 2002 to 2010, according to data from the US Energy Information Administration released in March, while manufacturing gross output decreased by 3 percent over the same period. Taken together, these data indicate a significant decline in the amount of energy used per unit of gross manufacturing output, reflecting both improvements in energy efficiency and changes in the manufacturing output mix, according to the research.
