Drives & Controls - Could a basic energy audit prove the saviour of UK industry?


As uncertainty surrounding the future of energy prices grows, and firms are pressured into attempting to reduce their carbon footprint, there has never been a better time for industry to consider the merits of variable speed drives and high efficiency motors. Manufacturer ABB has developed an energy audit that quickly and accurately pinpoints the potential savings in an industrial plant

A variable  speed drive (VSD) and electric motor combination, when used to control the speed of pumps and fans, can reduce the energy bill of these applications by some 70% with a payback in less than 12 months.

And yet a survey of British manufacturing managers with engineering roles has revealed that they do not regard VSDs as being the best way of cutting their companies' energy bills. The survey, conducted for ABB, reveals the 67 engineering managers surveyed placed VSDs at the bottom of a list of the ten most effective measures for cutting energy bills.

Joint top of the list were negotiating better prices with their company's existing energy suppliers and fixing compressed air leaks. ABB had expected the survey to show significant differences in attitude between the financial and engineering managers, with the latter appreciating the role that high-efficiency technologies could play in cutting energy bills.
The financial mangers believe that clamping down on visible waste, such as inefficient lighting and compressed air leaks, is important. Investing in equipment that makes industrial processes more efficient came at the bottom of their list.

"This list is back to front," says Ruddell. "Making industrial processes more efficient can save much more than the other methods, but financial managers are simply unaware of the savings they can make. Most companies can save thousands of pounds worth of electricity and some can even save hundreds of thousands of pounds, often at comparatively low cost. Changing electricity suppliers is not going to make much difference at all in a market where prices rise across the board," he adds. "In addition, this does nothing to reduce the company's carbon footprint, which also ought to be a priority."

ABB is in the vanguard of energy promotion, launching, in 2004, its award winning 6-step energy saving plan.

6-step energy saving plan
The plan documents six basic steps towards understanding and planning an energy saving campaign.
Step 1. The facts:
Gives an insight into the latest thinking on the Climate Change Levy and UK government actions to encourage greater energy savings.
Step 2. The savings:
In just half-a-day, an energy audit can help identify the applications that offer the best energy saving opportunities.
Step 3. The finance:
Offers information on how to finance a drive purchase while still benefiting from the government's Enhanced Capital Allowance.
Step 4. The products:
Guides the end-user through selecting the best motors and VSDs for specific applications.
Step 5. The proof:
Gives examples showing how industry has benefited from using VSDs and motors.
Step 6. The action:
Gives advice and further contact information at ABB and its extensive UK channel partner network.

Energy saving audit
At the heart of the 6-step plan is ABB's energy audit. On a typical industrial site with a £150,000 annual electricity bill, £100,000 will be spent on running motors. For example, are any motors or fans running on full power all the time when they could be driven by demand?
The answer is a professional energy audit. Undertaken by a trained engineer, an energy audit will identify those applications that would most benefit from the introduction of VSDs. The results, based on measured data from the application, will help a user target their investment so that it produces the highest possible savings and gives the best return. ABB has devised a very simple and methodical energy audit that presents the customers with hard, compelling facts about the energy they can save.

1. Outlining the scope of supply
During an initial meeting the audit engineer takes a look at the inventory of motors contained within a plant.

Energy surveys are most suitable for processes involving motors of 11kW or higher, used on large pumps and fans. This is where the savings from a VSD really start to look good compared to the investment cost. Often payback times of two years and below and sometimes under one year, can be achieved. ABB meets the end-user and outlines the benefits of the audit in detail, together with any assistance the end-user might need.

2. Collecting the data
The data collection phase is an active phase. It involves an on-site audit with selected fans and pumps, to determine operating parameters such as voltage, current and power factor and the energy being used. This stage will usually be performed over seven days to gain a complete picture of the plant's typical energy use. The end-users own staff may become involved at this stage although different auditors have different approaches.

3. Analysing the data
Following the collection of the data, the findings will be analysed and potential savings identified using dedicated software. The findings will be methodically presented - often tables or graphs will be created to help see where savings are likely to arise.

4. Recommendations
The action plan will then be prepared, usually comprising an Executive Summary and a detailed engineer's report, highlighting applications that can save the most. The figures will normally be translated into monthly savings, and there will be detailed recommendations for fitting particular VSDs or motors. The report should also clearly show the expected payback time on fitting new equipment.

5. Implementation
While not strictly part of the audit the aim is that the recommendations should be fully implemented. Once new equipment is fitted it is normal to track the actual savings against the predictions shown in the report. This will also help justify the investment in VSDs.

6. Benefits
An energy audit carried out by ABB or one of its channel partners brings the following benefits:
- Clearly identified energy savings
- Complete audit results and energy saving calculations 
- History of other audits and associated energy savings
- Proposed payback times 
- Degree of customer training given as part of the process
There are also other aspects to consider, for example whether financial options are available and if your supplier offers a replacement drive scheme.

Carbon emissions calculator
More recently, ABB has added another tool to its 6-step energy saving plan. As carbon emissions take a higher priority on company boardroom agenda's, ABB has developed a simple to use and understand carbon footprint calculator.

The user enters a motor's rating, and the calculator shows the energy savings in kWh, as well as the monetary savings, the cost of a suitable drive, and the payback time.
"Quantifying the carbon footprint helps organisations to manage their footprint and reduce emissions over time," says Ruddell. "But motor energy use is frequently overlooked, despite being the largest are of electricity use in industry.
The carbon calculator can be accessed via

Corus Strip Products
It was just such an energy audit that produced spectacular benefits for a steel maker in Port Talbot South Wales, saving £1m on its annual energy bill.

Corus is one of the biggest steel making companies in the UK with annual output of five million tones. Energy was Corus' second biggest cost after raw materials and with energy prices rising year on year it was important that energy expenditure was minimised.
As part of a plant-wide energy saving programme, 24 ABB industrial drives, ranging from 140 to 400 kW, where installed to control pumps on the hot strip and cold mills, plus three fans on the coke ovens. The cost of the drives about £1m; the whole project including pumps, cabling etc. is around £2.5m.

"The pump and fan motors were oversized and running longer hours than necessary," Says Guy Simms, leader of the Energy Optimisation team at Corus Strip Products. "But with the ABB drives we are now installing, we can fine-tune the applications reducing energy consumption."

McKechnie Automotive and Engineered Plastics
Following an energy audit at McKechnie, a manufacturer of engineered plastic assemblies ABB was able to reduce energy costs by over 30%.

The plastics manufacturer based in Pickering brought in Halcyon Drives, an ABB Drives Alliance partner to improve the efficiency of their injection moulding machine. Typically most injection machines are hydraulically operated and often waste between 20 and 50 % of the electrical power they consume. By adding a variable speed drive it is possible to control the speed of the pump motor to deliver the precise amount of electricity needed for each sequence in the injection moulding cycle.

"By introducing variable speed drives our energy cost has been significantly reduced" Says Rob Howlett senior process engineer for McKechnie.