The toughest challenge for The Times’s carbon champions is being faced by Allied Glass, which uses vast quantities of natural gas to heat its furnaces and electrically powered compressed air and fans to form and cool the bottles it makes.
As a high energy user, the company has worked hard to make its manufacturing process efficient, but increasing energy costs and the need to cut carbon emissions have encouraged it to embark on a fast-track carbon management programme.
Consultants examined operations at the Leeds and Knottingley factories in West Yorkshire and made recommendations to achieve energy savings. They also produced a 92-page report on the feasibility of using renewable energy. Managers and directors of Allied Glass will sit down in two weeks to agree an energy policy and priorities for implementing the recommendations. “We have a lot to consider, including how much more to do on the operational side and whether to appoint a manager to focus attention on energy usage,” says Brian McMillan, technical director.
Opportunities include increasing the combustion efficiency in the furnaces, which operate non-stop to produce molten glass from raw materials. The glass passes through channels to reach the correct temperature and drops into a forming machine powered by compressed air. Cooling fans used in the process have been fitted with inverters to make them more efficient. The newly formed bottles and jars pass through an annealing lehr (oven) to cool down before moving on to conveyor belts for quality control and packing.
The lehrs are often adjusted to take the largest containers, but energy could be saved by trimming them back when smaller bottles are being cooled. The consultants also identified an opportunity to recover waste heat from the compressor house to warm the inspection and packing area. They estimated that waste heat recovery, blocking air leaks, correcting misapplications in the processes and monitoring compressed air could save 5,300 tonnes of carbon-dioxide emissions a year — one eighth of the Allied Glass total.
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With its current level of emissions likely to exceed EU limits — which will affect the company from 2008 — the measures could be vital, but directors must decide if the investment required will justify the savings. Further studies will be conducted on renewable energy, including a wind turbine for the Knottingley factory, using biomass fuels and replacing the oil currently stored as a back-up to natural gas with waste cooking oil. “The report has given me the tools to investigate the different processes and conduct a cost analysis,” McMillan says.
He adds that one of the biggest ways of saving energy is by supplementing the usual raw materials of sand, soda ash, limestone and chemicals with “white flint” — recycled clear glass that takes less time and energy to heat