Cut reaction

By Paul Gander

- Last updated on GMT

Related tags Variable-frequency drive Adjustable-speed drive Electric motor

Many companies already feel they've taken action to cut sky-high energy bills. But where might investment make further savings?

The resurgence of the environmental agenda over the past decade has, in many ways, revisited the 'green' issues first aired in the 1970s. Intriguingly, some of the technological fixes of the pre-Thatcher era have also been returned to.

And once again, a sound cost as well as sustainability rationale underlies the trend.

Take the example of combined heat and power (CHP). According to Daman Ranby, director at construction, mechanical and electrical consultancy Edmond Shipway, this technology was very much a child of the oil crisis of the 1970s. But it has come into its own again as energy bills have spiralled upwards.

CHP uses a combustion engine to provide heating and hot water while also generating electricity. Most installations where Shipway is involved are gas-fired, but wood chips and rapeseed oil are among the other alternatives.

Payback period

"The electricity these systems produce offsets the factory's energy requirements,"​ explains Ranby. "It could, typically, be a quarter to a half of a manufacturer's usage."

A firm with a 10,000m² facility will need to invest around £750,000. "CHP installations have around a three-year payback period. That is often on the horizon of how far forward many food companies will invest,"​ he admits.

Payback does not only come in the form of savings on energy bills. There is also a significant reduction in Climate Change Levy (CCL) payments, which amounts to savings of 43p per kilowatt-hour (kWh), says Ranby.

Moreover, a CHP system qualifies for Enhanced Capital Allowances. This allows a business to write off the entire capital cost in the first year against taxable profits.

But only in rare cases can CHP be used to meet a food manufacturer's entire electrical requirements. "You size these systems on the heat output,"​ Ranby says. "If you sized one on the power requirements for the facility, you'd end up generating too much heat."

For larger firms, relatively small changes to individual lines or machines can translate into significant energy savings when rolled out across the plant. So for instance, a couple of years ago, Cadbury's Trebor Bassett plant in Sheffield upgraded the 13 gum stoves that feed into its Jelly Baby process.

Maintenance, repair and overhaul company Brammer replaced 11kW motors with 4kW motors on each stove and added a variable speed drive in each case. The result was an estimated annual saving of 700,000kWh, or £59,500, says Cadbury.

"The 4kW motors are equally effective and, with new Polychain belts and variable drives, they are remarkably economical,"​ said chief engineer at the Sheffield plant Tim Jefferies.

Zero-waste policies

Among food manufacturers, zero-waste policies are fast developing in relation to utilities and infrastructure, as well as materials and by-products. The focus is on capturing and harnessing what would otherwise be lost, be it heat, power or even air.

Robert Wiseman Dairies recently installed a refrigeration system at its Trafford Park, Manchester, facility at a cost of over £1.3M. This cools milk between pasteurisation and bottling and prior to shipping.

"The revolutionary addition to this installation is the heat pump which captures heat extracted and generated by the refrigeration system, and converts it into hot water,"​ says a spokesman. "This is then used in the pasteurisation process. Previously, the hot water and steam used in the process were generated by gas-powered boilers."

According to Wiseman, the system has cut the plant's gas consumption by around 50%. Water consumption has also been successfully targeted at this and other dairies.

Shipway, too, has worked on projects harnessing waste heat from coldroom chillers. But in Ranby's experience, chillers that take temperatures down to freezing or just under can only be used to heat water to around 20°C. "Where the chiller goes down to -30°C, water can be heated to as much as 70°C," ​he says.

A different type of wastage can be tackled through voltage optimisation. Ranby says this offers the twin benefits of a relatively modest capital outlay and what are often shorter payback times than, for instance, CHP.

This involves fitting equipment to the incoming power supply. "That supply should be 230V,"​ he explains. "In fact, it is 245V. Motors are typically designed to run on voltages as low as 220V. That means wasted energy, so these systems convert the voltage to the level required, and feed back the excess."

Fitting a voltage optimiser can be disruptive, says Ranby, but they cost around £60,000 and payback can be "in as little as two years".

Energy audits

Brammer picks up this theme, and the specific benefits of energy audits. "Correctly designing, specifying and maintaining power transmission and compressed air systems can reduce energy consumption significantly,"​ says head of marketing Jeremy Salisbury.

"Typical recommendations could include the specification of correctly sized, higher-efficiency electric motors, the use of variable speed drives (VSDs) on variable torque applications such as pumps and fans and the use of more energy-efficient drive belts."

Like voltage, compressed air is an area where correcting invisible waste can yield impressive energy savings. As Salisbury explains, savings can result from applying it more efficiently. But identifying leaks can perhaps have the greatest impact.

Iain Cameron, product manager at anti-static and air technology company Meech, points out that applications of compressed air in a food manufacturing environment can stretch from the conveying of products and empty packaging to cleaning, cooling and drying.

While compressor manufacturers are working to develop more cost-efficient systems, he says, there is currently no energy-saving alternative technology.

Meanwhile, despite the fact that factories can lose thousands of pounds a year compressing air that is then allowed to leak into the atmosphere, this is only now being recognised, says Cameron. As he puts it: "If it was a tap, someone would go and turn it off."

Cameron believes that, where a company has not reviewed its compressed air system for years, savings of 50% or over can be made.

As Brammer points out, the use of VSDs can make a sizeable cumulative difference to energy bills. Says Salisbury: "The drive slows the motor speed, for example on a fan or pump, to match the demand for delivery, and consequently reduces power consumption. Cutting the motor speed by 20% reduces the power requirement by about 50%."​ It is surprising how many applications have still not harnessed this technology, he adds.

According to Ranby at Edmond Shipway, the use of VSDs can mean a 5% or 10% reduction in energy requirements. This can provide payback in as little as a year.

Any operation is likely to be looking hard at alternatives to the traditional heat processing and ovens it employs. When it comes to single pieces of equipment, these are clearly the most likely to yield dramatic energy savings.

But most plants will offer opportunities to reduce energy loads on specific processes. Such as the container rinsing and washing that precedes filling. Many air rinsing systems use compressed air. But, as Meech explains, firms aiming to reduce water consumption are understandably reluctant to replace it with the high energy load of compressed air.

Meech is offering an ionised air rinse unit, the difference being that its IonRinse system uses fans rather than compressed air. Product manager Adam Battrick says: "Reductions in energy costs will vary dramatically, but payback can be in as little as six months."

Despite ionised air's greater ability to remove debris and dirt, there can be hygiene concerns in filling. In fact, the system is often used to clean preforms prior to bottle blowing. Battrick says: "We're looking at projects aiming to put ionised air rinsing just before filling."

One of the more interesting emerging technologies is the light-emitting diode (LED) light source. According to Ranby at Shipway, Philips has confirmed that LED tubes to replace fluorescent tubes are "just around the corner"​.

He says: "These will halve the power load while maintaining the same output. There is a further advantage, that they last five or even 10 times longer than fluorescent tubes, and so help to cut maintenance costs, too."

Self-interest is not the only impulse driving such improvements. Regulation is increasingly being used as a tool to reduce carbon footprint, be it through the CCL or other measures such as the Carbon Reduction Commitment.

To date, Building Regulations that require a reduction in energy use of around 40% in new office space do not apply to factory processing. But who knows what 2013's revision will bring?

The beginnings of regulatory pressure to reduce the energy load on new processing facilities cannot be far off.


Brammer: 08447 363616

Edmund Shipway: 0115 975 8595

Meech: 01993 706700

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