Lateral thinking

As power costs rise and emissions trading schemes become charges for excessive consumption, firms across all sectors seek different ways to slash energy usage and emissions. Stuart Nathan reports

Energy reduction has long been the poor relation when it comes to improving manufacturing processes. Relatively low energy costs have led to industry being fairly profligate with it — from lighting which stays on all the time to compressors running flat-out.

But as energy costs rise and emissions trading schemes become charges for excessive consumption, companies are seeking ways to slash energy usage and emissions profile. And lateral thinking is the order of the day.

Adnams Brewery, of Southwold, Suffolk, has recently embarked on a series of investments with an environmental slant, including a distribution centre using solar water heating and a grass-covered roof to improve insulation; a new bottle for its beers, designed to be the lightest on the market, and a major overhaul of the brewing process itself in a new brew hall.

‘Some parts of the old brewhouse were over 100 years old,’ explained chief engineer Bob Lee. ‘and we required additional brewing volume to meet buoyant demand. We’d been working the brewhouse much harder than it had been designed for. We also wanted to reduce the amount of energy we were using, and improve the extraction from the hops and malt we use.’

The major difference between the old process and the new comes with the boiling of the wort — the solution obtained by mixing ground malted barley with hot water — to increase its concentration before fermentation. ‘We used to have very little process control over that boiling, and as we were driving off the water, the vapour was vented straight into the atmosphere.’ The new process regards the energy in the steam as a resource, so the steam passes through a vapour condenser.

The heat given up by the condensing steam is transferred into water via a heat exchanger. This heats a separate stream of water that flows into a 66,000-litre energy storage tank, where the temperature reaches 98°C. When the brewers fill the copper with a fresh batch of wort to be boiled, the wort flows from a holding vessel into the copper via a plate heat exchanger, where it is heated by the water from the energy storage tank. ‘We put the wort into the exchanger at 72°C, and it comes out at 96°C. So that’s 24° C of temperature rise we get for nothing. That’s good financially, and it’s great environmentally.’

The system also optimises the flow of steam for process heating, which reduces energy consumption and improves the consistency of the process. ‘We know it will be done the same way, every batch,’ said Lee.

The process is still in the commissioning stages, so it is too early to quantify the exact amount of energy it will save. However, along with its other innovations, Adnam’s improved energy usage is sure to be considerable. ‘We tend to take a lead in these sort of issues among medium-sized breweries,’ said Lee.

While Adnams undertook its own study on efficiency, other firms will often turn to specialists. Some energy utility providers are now offering consultancy services, which involve energy auditors visiting the company and examining its energy usage, suggesting ways to save energy which range from the complex and radical to the simple.

One such scheme is the Advanced Efficiency Programme (AEP) offered by EDF Energy. Originally conceived as a customer retention strategy, it works by committing to reduce energy usage by a fixed amount over a fixed time period.

‘You have to take account of the ways that energy is used,’ said Pierre-Jean Lahourcade, energy efficiency manager for major businesses at EDF. ‘There’s no point telling people you can save them €10,000 (£6,700) a year, and then charge them €10,000.’ Typically, he added, the cost of the service is around 10-20 per cent of the total value of the savings commitment. This is legally binding, and if the target is not met, EDF undertakes to refund the overspend.

The reaction from customers to the AEP service often illustrates how little companies understand about reducing carbon emissions, said Lahourcade. ‘Quite often, companies will come to us asking about installing renewable energy generation. And we say sure, we can do that, but we can also make you more carbon neutral by just reducing the amount of energy you use. Then we start meeting with the site managers and plant operators, and looking at the way energy is used. That’s where we start to see savings.’

For example, he explained, if a company using 50GWh of energy wants to reduce its carbon emissions by 10 per cent through renewable generation, it would need to install a turbine with a minimum capacity of 2MW, which would cost about £2m. On the other hand, it could reduce its energy intake by the same amount, which would cut energy costs by £125,000 (gas) or £300,000 (electricity) — for an outlay which would certainly be less than that for the turbine.

Although it seems strange that an energy company would be keen for its customers to spend less on energy, Lahourcade said: ‘if we help them, they stay with us; and almost all the time, most of the savings are in terms of gas.’

Savings can come from a variety of sources. For example, an aerospace company was increasing the density of carbon fibre materials by heating them in a furnace at 3,000°C. The furnace was insulated with fibre pads, but the carbon fumes from the process filled the fibres, and the insulation had to be completely changed every six months.

The AEP team tested various alternative insulation materials at EDF’s R&D centre near Paris, and found a material which wasn’t fouled by vapours. This increased the availability of the furnace, improved the firm’s knowledge of its process, and led to annual savings of some £2m.

Sometimes, however, the process can be much simpler. One client saw its energy bill drop by £21,000 in one year after AEP re-programmed its heating and air-conditioning systems so they weren’t battling against each other.

One of EDF’s largest clients is French aerospace giant SAFRAN, whose jet engines subsidiary SNECMA underwent the AEP process in 2002. EDF committed to reduce the company’s energy usage by five per cent across all plants. In the event, with the agreement extended to cover the whole SAFRAN group when the company merged with SNECMA in 2005, the savings amounted to 10 per cent, equivalent to a reduction of 76.5GWh per year, 3,290 tonnes of CO2, or some £3.8m in monetary terms.

Around half of the savings came from changes to SAFRAN’s compressed air, heating and lighting systems. In the initial stages of the project, this involved installing building management systems to switch off lights, and fine tuning fan-coil and air-handling units. The second stage, involving more investment, included a wide-scale search for leaks in the compressed air system, installing software to switch off computers and printers when not in use, and optimising temperature set-points for painting cabinets. ‘Reducing set-points by even a degree or two can have a large knock-on effect on saving,’ said Lahourcade.

Despite the large energy savings derived from these types of changes, it could be that even larger emissions reductions could come from more radical thinking — redefining production processes, or even re-thinking the paradigms of businesses, products and services. Prof Stephen Evans, of Cranfield University’s School of Manufacturing, believes this sort of thinking is vital if major reductions are to be made.

‘One of the first things you’ve got to do is to put a boundary on the system you’re trying to understand and impact on,’ he said. If a company is trying to control the emissions from the processes it undertakes itself, that suggests one set of strategies; but if it is trying to reduce the emissions associated with the product, then a new set of variables have to be considered and managed.

The materials used in products are a prime example. ‘If I make my packaging out of aluminium it’s lighter, so my transport bill will come down,’ he explained. ‘But aluminium takes more energy to make in the first place, so you’re increasing the energy bill further down the supply chain.’ But aluminium is lower energy than steel if it has been recycled, he added, so depending on the proportion of recyclate in the aluminium, it could still represent a net energy reduction. ‘We’re pointing to a serious complexity now, and that scares firms.’

A radical rethink of engineering techniques and priorities is equally scary but could reap large rewards, said Evans. For example, in the metalworking sector, arrays of small machining centres could be preferable to a single, large, high-speed machine tool. ‘You could allow yourself 20 minutes to machine something rather than five, because you can afford 10 machines rather than one, and you’ve still got the same throughput. You’ll have a lower energy bill because those 10 machines use energy very differently from a large one, which will use a lot of energy to change the shape of the materials. And if those smaller machines are more energy efficient per unit product, there will be ways to use that to manage yourself towards a lower energy usage.’

Even more radical is the redefinition of products and services. In the automotive sector, for example, overall emissions can be driven down by subcontracting out parts of the process. This is already happening with paints and finishes, with paint makers more and more operating the spray process, rather than just supplying the paint.

‘Paint is the single most environmentally messy thing you do in car plants,’ said Evans. ‘You have to carefully manage emissions to air and water; paint itself is expensive and energy-intensive to produce and failing to paint a car body properly is incredibly expensive.’ In some plants, car manufacturers now sell the body to the paint manufacturer as it enters the paint shop. ‘They own the car while it’s going through the plant, and they sell it back once they’ve painted it,’ said Evans. ‘And what that does is incentivise the paint company to use less paint, because that means they make more money. This is a form of dematerialising: by selling the service, you’re encouraging the technical expertise of the paint company to come to the fore.’ And as material usage comes down, so do the energy bills associated with making and applying that material.

‘The key point about this type of thinking is that incremental innovation — saving 10 per cent of your energy bill by installing a new machine — might be cost-efficient within that element of the system, but if you look at the whole system, then you might be able to save 80 per cent of your energy by spending less money per percentage point, or per kilojoule, if you take a more radical strategy,’ said Evans. It’s a difficult and scary choice, but it’s one increasing numbers of companies may have to face.