Energy data does the business

Monitoring and analysing energy consumption has enabled the world’s largest beverage can maker to dramatically reduce its energy bill. With several million cans produced every day at the Milton Keynes plant of Rexam Beverage Can Europe & Asia, it is vital to get the technology just right.

Project engineer, Ian Grant, is currently working on energy saving programmes. His initiatives in this area have enabled the plant to reduce its energy intensity by a third, with more energy saving measures due to be implemented over the

coming months.

This is important, not just for the profitability of the company, but also because it has to meet strict efficiency targets set out in its Climate Change Agreement, negotiated with the government. The installation of a sophisticated monitoring and targeting (M&T) system developed by specialist energy company, Stark Software International, plays a key part in achieving the required savings.

Facing the challenge

Rexam Beverage Can Europe & Asia is part of Rexam, one of the world’s top five consumer packaging groups. Like most large industrial businesses, it faces the challenge of using resources as efficiently as possible in order to run production lines cost-effectively and profitably.

The company is a signatory to the Climate Change Agreement negotiated by its sector association, the Metal Packaging Manufacturers’ Association (MPMA). This requires the sector to meet certain energy saving targets. In return, its members gain an 80 per cent discount on payments under the Climate Change Levy, a tax on fossil fuel (and electricity) use.

“In order to control our energy use, we clearly have to know where it’s being used,” says Grant. “To do this, we’ve installed a number of sub-meters to give us the necessary information.” The data from the metering is collected and analysed by a system created for Rexam by Stark Software.

Monitoring and reporting is currently carried out by Wantage-based RAB Energy, who provides a bureau service to the Milton Keynes factory. David Higgins, CEO of RAB, had been working on long-term energy saving proposals with Ian Grant. It became clear that in order to present a convincing business case to the board, accurate data on present day trends was needed. To do this, sub-metering would be essential.

“You have to be pro-active to save energy and that means planning ahead,” says Higgins. “However, like any other business proposal, initiatives have to be based on hard facts, which is why we needed the data from the sub-metering.”

Measuring consumption

Readings from nearly 100 sub-meters are analysed by the Stark software system. The meters measure the energy and water consumption of key items of equipment around the plant. Half-hourly readings provide a comprehensive picture of utility usage. This gives Grant the information he needs to target efficiency improvements across the site.

“You can have too much data, especially when it is being collected every 30 minutes from so many different locations,” he notes. “That’s why this system is so attractive. It gives us the flexibility to select what information we need.”

Not all of the energy saving strategies can be implemented immediately, so the company concentrates on specific targets and builds in more detail as time goes on.

Readings are collected from the meters by four data loggers provided by Stark’s associate company SHM. Each of these has 24 channels. SHM came up with an innovative communications solution which permits all the meter readings to be accessed through a single modem.

The four loggers are networked and the first is connected to a single modem. The Stark system dials into this modem, requesting the readings. The message travels along the network to the appropriate logger and downloads the relevant meter reading. In this way, all the sub-meters connected to the system can be interrogated via the single modem. This reduces the telecoms and wiring costs substantially.

The system is now providing detailed information about all aspects of energy and water usage. The Milton Keynes plant operates 24 hours a day, seven days a week. A number of crews work a rotating shift system. With the Stark system in place, the performance of each shift can be tracked.

The detailed analysis generated by the software is resulting in substantial savings across a number of areas. “If you don’t keep an eye on energy consumption, it soon creeps up,” remarks David Higgins. “But the level of detail provided by this system means you can find out just where energy is being wasted, and where it can be saved.”

All the crews are highly motivated to achieve maximum productivity. This can work for – or against – changes in operating practice. “One crew assumed that leaving the air compressors running all the time through the shift was the most productive way to work,” recalls Grant. “It meant that compressed air was continuously available.

“However, using the reports, we were able to show them this was not the most efficient way to proceed. Once they could see that changing this practice would increase efficiency – and productivity – they were very happy to do so. But we could not have convinced them without the data.”

Ian Grant and his team have installed variable speed drives to equipment to reduce consumption. An energy reclaim system is being fitted to the drying ovens, which will replace some of the heating elements. The ‘jewel in the crown’ though, is the improvement to the compressed air systems. Producing compressed air is expensive and so, therefore, is any wastage. By implementing a centralised strategy for improving efficiency and eliminating wastage, the electrical demand for the air compressors has been cut by 30 per cent.

The case for investment

As an archive of historical data is built up and as site staff are trained, so operation of the Stark system will gradually transfer from a bureau service to an in-house engineering department responsibility.

The sub-metering and the analysis software were originally installed to substantiate the business case for investment in energy efficient technologies. This has been achieved at Milton Keynes and Grant is using the experience gained to argue the case for action at other plants in the group. “We set energy targets each year,” he notes.