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. Equally impressive is the impact on carbon emissions.
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 that 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. The engineering managers also gave high ratings to changing energy suppliers and using more efficient lighting.
The survey, conducted for ABB last year by Benchmark Research, also included 52 managers with financial and accounting roles. More than half of them believe that changing electricity suppliers is the best way to reduce their companies’ energy costs. The chart (above) shows the favoured methods for cutting energy bills for both the engineering and financial managers.
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 by upgrading existing processes, 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."
The results of the survey are even more surprising when the amount of marketing by the largest VSD manufacturers over the past decade, targeted at the engineering community, is taken into account.
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.
Energy saving audit
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 in order to secure the substantial savings possible.
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.
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. An audit provides a good opportunity to look at a plant’s energy use and see where savings can be made.
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.
An effective energy audit will have several characteristics. These will generally include:
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. The ideal size, which gives the greatest savings and thus the shortest payback period, is between 22 and 90 kW. Often payback times of two years and below and sometimes under one year, can now 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. This could include information on access to equipment and help in setting up and connection of meters. They will also be interested in anything unusual that might affect the energy profile during the audit.
Research shows that much of the information in the market place on energy efficiency and the Climate Change Levy is confusing to the end user. So ABB devised a very simple and methodical approach that presents the customers with hard, compelling facts about the energy they can save.
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 energy auditor will look, not only at the fixed speed drives, but also any VSDs used, to see if the application is running at maximum efficiency.
The end-users own staff may become involved at this stage although different auditors have different approaches. Some will train on-site staff during the initial appraisal, others will do this subsequently. In either case the aim is that the site staff should be able to perform subsequent energy audits with minimal support.
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.
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. Often the recommendations will show that VSDs can provide excellent savings in particular applications. The report should also clearly show the expected payback time on fitting new equipment.
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.
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. “Again we are trying to simplify the message and get it into the boardrooms, particularly with the finance guys,” explains Ruddell. “Our on-line calculator shows how an organisation can reduce its carbon footprint by using VSDs to control its motors. The carbon savings are also translated into car and air miles to give a more human equivalent as to what carbon dioxide actually relates to.”
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.
"There are already many carbon calculators around but none, as far as we know, that addresses this huge area of energy use," says Ruddell. "Our new calculator aims to plug a huge gap in the market."
The carbon calculator can be accessed via www.abb.co.uk/energy
Audits in action
General Domestic Appliances
It was just such an energy audit that produced spectacular benefits for a cooker factory, saving £17,000 on its annual energy bill.
General Domestic Appliances Ltd, in Stoke-on-Trent, Staffordshire, makes 12,000 cooking products a week for its market leading Creda, Hotpoint and Cannon brands. Because of the increased energy costs that would soon be imposed by the Climate Change Levy, the company decided to look at the energy consumption of its wet fume plant, which extracts waste vitreous enamel from four paint booths. Some of the booths were not in constant use and were closed off by a mechanical shutter, yet the 132kW fan used to extract the waste enamel was run at a constant speed, wasting energy and money. GDA asked ABB Drives Alliance partner, Central Electrical, to conduct an energy audit on the plant.
GDA’s Plant Engineer Andy Rowe says: “Central Electrical’s report concluded that the fan would consume £30,000 of electricity per annum if nothing was done. They estimated we would save approximately £16,000 on the energy bill for the wet extraction plant in the first year if we adopted their recommendation of an ABB industrial drive. In fact we saved £17,000 and achieved a payback period of only four months.”
West of Scotland Water
Following an energy audit at one of its pumping stations, West of Scotland Water expects to make savings in electricity costs of £80,000.
The Lomond Street Wastewater Pumping Station in Helensburgh has more than doubled its efficiency since two ABB industrial drives were installed by ABB Drives Alliance partner EDC (Scotland) Ltd. The drives will save at least £80,000 in electricity costs over a 20-year life span whilst minimising the risk of overflowing, as pump throughput has been increased from 14 to 30m3 per kWh consumed.
“Indications are that the electricity consumption has been reduced by 48 percent compared to the same period in the previous year “, says Charles McCaig, Electrical Design Engineer at West of Scotland Water’s Planning & Capital Procurement Department.
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