Feature

Food manufacturers focus on energy efficiency

Many food manufacturers are studying the potential to make energy efficiency gains

Although energy resilience is also key, many more businesses are investigating where the biggest potential energy efficiency gains lie.

According to Food & Drink Federation (FDF) figures, the sector reduced absolute carbon dioxide emissions by 41% between 1990 and 2014.

Arguably, much of the heavy lifting was carried out by larger businesses under Climate Change Agreements (CCAs), after the introduction of the Climate Change Levy in 2001.

More recently, reduced energy costs have become a driver in their own right for businesses large and small. But, according to Barclays, energy-related concerns have moved on again, and are not just about cost but about wider energy resilience.

Its Powering On report, just published, takes this as its theme. It makes the point that food and drink is not in fact among the most energy-dependent of the UK’s industrial sectors.

“But there’s been a movement from relying on labour to increased use of robotics and automation, and with this comes a greater reliance on energy,” says Barclays’ head of manufacturing, transport and logistics Mike Rigby.

“With small to medium-sized enterprises [SMEs], too, there’s a sharp divergence between those investing little in automation and those investing the most.”

A greater reliance on energy supplies brings with it three “challenging features”, he argues: the price of energy, and how critical that is to the business; resilience to any outages in supply; and a focus on the sources of energy, especially with regard to carbon footprint.

Companies were rightly concerned about price in the past, but there is now much more of a three-way pull of equal measure, he notes.

Price and continuity of supply (Back to top)

Both in relation to price and continuity of supply, Rigby says: “If I’m completely exposed to a single supplier, in this case the National Grid, that’s an uncomfortable place to be.” This would be true of any type of supplier, he emphasises.

“The bigger operators, perhaps with multi-site operations, can seek out a separate supplier or take a renewables route. But for SMEs, the only lever they’ve got to pull consists of energy-efficiency measures.”

Food industry sites often struggle with plant that is well beyond its shelf-life, older buildings and limited space for expansion, says Tom Jordan, sustainability consultant at Lorien Engineering Solutions.

“High-expenditure projects catalysed by a particular issue – such as ageing boiler plant or escalating waste water treatment costs – are being implemented, often with significant energy consumption benefits,” says Jordan.

“This may be through self-production, such as anaerobic treatment, or enhanced efficiency compared with traditional systems, such as combined heat and power.”

The importance of boilers cannot be overstated. Two years ago, the government’s Decarbonisation and Energy Efficiency Roadmaps to 2050 for the food industry pointed out that a lifespan of 30 or even 40 years was not exceptional for a boiler.

The report quoted FDF figures attributing 54% of sector energy consumption to boilers.

Stephen Barker, head of energy efficiency at Siemens, points out that the vast majority of ‘energy’ in a food-industry context is not electrical but fossil-fuel based.

Fossil-fuels (Back to top)

Ratios vary enormously depending on the type of operation, but the FDF’s 2012 industry averages, quoted in Roadmaps to 2050, were 66% natural gas, 5% coal and oil and 28% electricity.

Barker underlines the importance of an energy-efficiency strategy. “As an end-customer, you tend to look for the largest consumers of energy: the biggest targets,” he says.

“We believe this is not the most effective approach. We take a holistic view. An ad hoc approach might miss interactions between different elements, and that might include some quick wins.

“For example, you might look at heat and cooling as discrete elements, when in fact optimising them together can be far more effective.”

Of course, as a part of that bigger picture, relatively minor changes can make a difference. At Mitsubishi Electric, product manager Matt Handley (see panel story) says that while individual variable speed drives (VSDs) can come with a relatively high price tag, payback periods will typically be calculated at under two years.

According to Siemens, motors account for around two-thirds of electrical energy consumption in industry as a whole, and in some food and drink plants may add up to much more than that.

“Effective control provides around 80% of the benefits of energy management,” says Barker. “The other 20% benefit comes from the use of more efficient products.”

Even knowing where precisely energy is consumed in a factory can be a challenge for manufacturers, says Siemens. “A lot of plants simply don’t have that granularity of detail of energy consumption,” Barker says.

In the view of Schneider Electric, this level of detail is becoming increasingly available, even for SMEs. “In the past, you needed complex and expensive architecture and software analytics to obtain this type of data,” says Chris Haines, marketing director for industry.

“Today, smart devices are being built with sensors that can connect directly to cloud-based systems and straightaway start collecting data.

‘Energy efficiency opportunity’ (Back to top)

“We’ve done a lot of work on intelligent motor control in food and drink, which represents a huge energy efficiency opportunity. It offers control and intelligent power metering by cell and by device.”

On the human side, SMEs are more likely than larger businesses to suffer from the lack of a dedicated energy manager, says Haines. “Also, food industry margins are tight, and contracts are notoriously short, so it’s much more difficult to justify return on investment,” he says.

As Lorien highlights, tight production schedules and limited shutdown windows are another characteristic of the industry. This means it is not uncommon to find energy losses resulting from ‘housekeeping’ oversights such as steam or compressed air leaks.

Despite all these obstacles, the sector’s knowledge-base with regard to energy management has grown, according to Steve Hughes, sales manager for low-voltage drives at ABB.

“Businesses are having to meet company-set and government-set carbon emissions criteria,” he says. “Meanwhile, the jigsaw’s got a lot more complex, and the legislation is changing all the time.”

In fact, with mandatory schemes such as the Carbon Reduction Commitment and Energy Saving Opportunities Scheme (ESOS) running in parallel, there appears to be an understanding at ministerial level that this legislative web is now too tangled and is in need of simplification.

As Hughes points out, under ESOS, companies coming under the scheme are required to undergo periodic energy efficiency audits, but are not obliged to implement any of the audit’s recommendations.

“Some of this is about education, but some is about investment cost and how any changes are funded. It’s about what gives you the biggest bang for your buck.”

The challenge, as Siemens explains, is that the biggest wins can rarely be isolated to a single point in the plant. They tend to be about more radical – and so more costly – reconfigurations rather than drop-in solutions.

 

 

Variable speed Drive use is still not optimal in food

Variable speed drives (VSDs) are not new to the food industry’s energy management toolkit, but they remain an under-used solution. And, even where they are used, they are often not always optimised.

Mitsubishi Electric’s Automation Systems division, first introduced VSDs some 35 years ago, says its product manager Matt Handley. “But they are still not always used where they could be,” he says.

“For example, if you’re installing a cooling system and you’re not particularly energy-conscious, you might opt for a system using a fixed-speed drive [FSD] with mechanical damping.”

In many cases, this will be inefficient, since the power input into the motor remains the same. With a VSD, on the other hand, voltage is ramped up or down according to need.

Applications will often combine fixed and variable-speed. So, for example, compressors use both types. But how they are used will depend on the size of the compressor, the use profile and energy management, says Handley.

“An end-user may use a fixed-speed compressor to handle the basic load with two or three VSD systems to manage any top-up requirements.”

Where the option arises, a single VSD can control multiple motors. “When the first motor reaches top speed, the inverter can switch back to full mains voltage,” says Handley. “The same process can be followed with, say, three or four motors.”

Food & Drink Federation (FDF) figures for its members in 2008 found that compressed air was responsible for 8% of carbon emissions.

UK business manager for Atlas Copco’s oil-free division Mark Ranger states: “If you’re considering VSDs for compressed air, the correct sizing is paramount.

“That means being clear about the demand profile, which includes future plans, too. An air compressor might be in use for up to 15 years.”

Compared with an FSD, potential energy savings could be of the order of 30%, says Atlas Copco. “That’s achieved through a combination of reduced offload power and a reduced operational pressure band,” Ranger explains.

“People tend to buy a VSD, connect it and think that’s it,” adds Handley at Mitsubishi. “But, in fact, that drive can be tuned – or configured – to maximise energy saving. This can account for 10–15% of the savings on that drive, maybe more. A lot of people miss out on this.”

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