Top Editors ... Energy efficiency: How to cut costs

Title: Energy efficiency: How to cut costs
Date: 22/05/2006
The continued pressure to improve profitability, whilst complying with energy regulations designed to protect the environment, means it is essential for manufacturers to keep up to date with the latest measures designed to improve energy efficiency. Food manufacturers have experienced as much as a 50% rise in energy costs, significantly impacting the total cost to produce the final product, according to Rockwell Automation in its new White Paper: How a wellplanned strategy can help the food industry more effectively manage its energy-related costs, which it published this year. “The key to effective energy management is information and knowledge – information on what’s happening and the knowledge to do something about it,” said John Kascur, vice president, Food Industry Initiative, Rockwell Automation. “Through our Power and Energy Management Solutions, Rockwell Automation helps food manufacturers gather the information they need to improve energy efficiency, lower energy costs and improve plant reliability.”

The Rockwell Automation White Paper highlights several case history examples of how food manufacturers have used energy management systems to control their energy consumption and reduce costs. It also includes a discussion of how power optimisation tools, such as variable frequency drives, can be applied to motor systems to significantly reduce the amount of energy used in a manufacturing process.

The company supplies a range of power monitors that can be deployed to obtain detailed information regarding energy use at a plant, down to process and even machine level. This data is then used to devise energy management plans to optimize energy consumption, thus reducing production costs at the plant.

According to Rockwell, one leading food and beverage manufacturer armed with detailed information regarding its energy usage (including peak power demand and the frequency with which its plants draw power at the maximum rate) was able to renegotiate its agreement with its energy utility, thus saving up to 10% of its annual energy costs.

Many manufacturers have already devised their own in depth energy saving plans that are reaping rewards in terms of returns on investment.

Allied Domecq’s winery at Clos du Bois in California developed an energy saving programme that draws on simple, practical methods to reduce energy consumption (and thereby costs), including increased use of insulation and the innovative use of natural resources, such as cool night air.

The company insulated its production building with 10cm plastic foam, which although more expensive than other forms of insulation, provides significant savings in energy use over time. Insulated skylights were introduced in the facility where the steel wine tanks are situated, which removed the need for electric lighting. Also, and very simply, most of the white grapes used in production are now picked at night, eliminating the need to chill them after crushing and further saving energy.

Also in the USA, Kraft Foods introduced an energy saving programme at its plants, including its coffee plant in Houston, Texas. It has reduced energy costs by simple measures such as turning off equipment when not in use and keeping boilers clean and well maintained.

Energy consumption by frozen food manufacturers is particularly high, given the additional costs of refrigerating the finished product before it reaches the retail outlets, and Unilever, for example, has taken various steps to improve the energy efficiency at its frozen food plants in Italy. At the Sagit factory in Cisterna the applied voltage used for lighting
was reduced, resulting in a decrease in energy consumption of 35%, which in turn produced a saving of about €50,000 per annum in energy costs.

Controlling processes

A manufacturer can save considerable amounts in energy costs by investing in more energy efficient equipment, which soon pays back the initial capital outlay, and by monitoring existing equipment.

According to the engineering specialist, ABB, a 20% reduction in the speed of a centrifugal fan or pump reduces energy consumption by at least 50%. Northern Foods in the UK benefited from the company’s know-how when it installed three ABB variable speed drives in the pumping system that cools the refrigeration units at the Riverside Bakery in Nottingham. The bakery now saves around £30,000 (€42,000) per annum in electricity costs.

To open the market for variable speed drives to lower volume manufacturers, ABB recently launched what it claims to be one of the smallest variable speed drives in its class. The 0.37 to 7.5kW general machinery drive enables smaller
panels to be designed and more drives to be inserted into existing panels. It also uses a new type of power semiconductor which decreases the need for cooling and is therefore more energy efficient.

According to ABB, the use of high efficiency motors can reduce energy consumption by 1 to 3% in fixed speed operations (and even more in variable speed operation). In addition, they are said to be built using better materials and have a lower running temperature, therefore requiring less cooling, which in turn increases their energy efficiency. The installation of advanced software applications to control a range of manufacturing processes can have a direct impact on both energy consumption and plant productivity. Fonterra Co-operative introduced software supplied by Pavilion Technologies (of Austin, Texas) to improve the operating efficiency of the existing evaporators and driers at its Kauri K2 milk powder plant in Northland, New Zealand; and Nestlé also uses Pavilion software solutions at some of its plants. Pavilion Technologies supplies a range of advanced process control (APC) software designed to allow operators to fine tune aspects of the manufacturing process, thus increasing energy efficiency, product quality and productivity. The Pavilion software used by Fonterra enabled the company to reduce the amount of total solids variability in the evaporators by up to 73%. This allowed operators to increase the total solids target in the evaporators, whilst maintaining viscosity limits. The result was a moisture reduction of up to 52% and a more concentrated material was sent through to the driers.

Thus the energy costs of drying the product were transferred to the more thermally efficient evaporators, reducing energy costs by 10 to 12%. It is also worth noting that the purchase cost of one of these applications can be recouped by the resultant savings in energy costs within a very short period. According to Ian Steele, director of consumer products at Pavilion Technologies, the typical pay-back period for its APC solutions is 6 to 12 months.

The use of alternative fuels derived from waste products from manufacturing processes can also be used to cut energy costs and reduce waste. Over 20 of Nestlé’s factories around the world now use spent coffee grounds as a supplementary fuel, amounting to around 800,000 tonnes per annum.

This measure reduces consumption of non-renewable oil as fuel and uses up waste material that would otherwise go to landfills, thus being energy efficient and environmentally sound at the same time.

As energy costs spiral throughout Europe, initiatives such as these and many others will become increasingly valuable for food and drink manufacturers seeking to improve their costs and contribute to the future wellbeing of the environment.


Cogeneration fuels fries production

Lutosa, the Belgian potato products manufacturer, has invested heavily in environmental policies for the past 15 years and most recently has joined with the Belgian energy supplier, Electrabel, part of the Suez group, to create a cogeneration plant fed by biogas.

Based on the principle of the joint production and consumption of heat and electricity, the cogeneration plant at Lutosa’s St-Eloois-Vijve site is the second such plant for Lutosa. The first was built in 2002 at the Walloon site in Leuze-en-Hainaut, Belgium, and both draw on the biogas produced from the fermentation of waste from the company’s waste water plant. Each production site has its own waste water treatment works where starch from the potato manufacture is recuperated as a raw material for the paper industry, and treated waste water is also reused for washing unpeeled potatoes. Both the heat and electricity produced are re-injected into the manufacturing process, and the new cogeneration plant represents an annual saving on electricity bills of 3 GWh (equivalent to the electricity consumption of 1,000 families, according to Electrabel), which covers 10% of the needs of the production unit at St-Eloois-Vijve. The heat produced is used to heat bleaching water and to dry potato products, and represents an annual saving on gas bills of around 3.2 GWh. At Leuze-en-Hainaut, 6.5GWh of heat and 5GWh electricity are produced, which cover 8% of the company’s needs.

“Achieving our long-term policy aims whilst protecting the environment forms an integral part of how we manage our company,” said Guy Van den Broeke, managing director of Lutosa, which has appointed an environmental co-ordinator to oversee its ongoing environmental projects. The company uses frequency deviators and modern high performance and environmentally-friendly equipment, and separates out waste such as wood, card, film and metal. Potato peelings are used as cattle feed and waste oil is recycled in the maintenance products industry or as a bio fuel. In total, Lutosa and Electrabel have invested €1,220,000 in the cogeneration project.