Case Study

Rexam Beverage Can - a Stark improvement in energy performance with Envision Energy

Monitoring and analysing energy consumption has enabled the world's largest beverage can maker to dramatically reduce its energy bill.

"Some people say that making cans is a matter of life and death, but we take it more seriously than that," says Ian Grant, tongue in cheek. With several million produced every day at the Milton Keynes plant of REXAM Beverage Can Europe & Asia, it is clearly vital to get the technology just right.

Ian Grant is one of the company's project engineers, 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 & Targeting (M&T) system developed by specialist energy company Stark Software International plays a key part in achieving the required savings.

Challenge

REXAM Beverage Can Europe & Asia is part of Rexam, one of the world's top five consumer packaging groups. It is a leading global beverage can maker and the no 1 can maker in Europe. 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. Energy is an important 'raw material': consumption has to be controlled and wastage eliminated.

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

Sub-metering

"In order to control our energy use, we clearly have to know where it's being used," says Ian 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 Envision Energy Ltd, who provide a bureau service to the Milton Keynes factory. David Higgins, Managing Director of Envision Energy, 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 David 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 Ian 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. It's not feasible to implement all the possible energy saving strategies on Day One. We need a focused approach where we can concentrate on specific targets and then build in more detail as time goes on. Most of the other systems we looked at didn't have this kind of flexibility."

Readings are collected from the meters by four data loggers provided by Stark's associate company SHM Communications Ltd. Each of these has 24 channels. SHM came up with a highly 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 in the plant that are connected to the system can be interrogated via the single modem. This reduces the telecoms and wiring costs substantially.

Detailed information

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.

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 Ian Grant. "It meant that compressed air was continuously available."

"However, using the reports, we were able to show them that 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."

Continual improvement

Shift productivity and energy performance are routinely analysed using the Stark software. Where one shift is doing particularly well, the reasons are identified and alterations proposed to the others. In this way, there is a process of continual improvement in operating procedures - and continual advances in efficiency and productivity.

The detailed analysis generated by the software is resulting in substantial efficiencies across a number of areas. "If you don't keep an eye on energy consumption, it soon creeps up", remarks Envision Energy's 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."

Compressed air

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%.

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. This is important for Ian Grant.

"We want our staff to be fully engaged in this process," he says. "We have energy champions in every department here. But for people to feel completely responsible for achieving continuing energy savings, they must feel they have ownership of the process. And this includes the procedures for measuring performance and setting further targets."

The business case

The sub-metering and the analysis software were originally installed to substantiate the business case for investment in energy efficient technologies. They have certainly achieved this at Milton Keynes and Ian Grant is using the experience gained to argue the case for action at other plants in the group: in the UK at Wakefield and also on the Continent.

"We set energy targets each year," he notes. "With the Stark Software system, we now measure in detail how much energy and water is being used and where. We then decide the most effective way to reduce consumption. But most importantly, we have the data to prove how worthwhile these energy saving investments have been."