ABB once undertook a survey of energy managers across the process industry. A key question was: “How would you best reduce your energy bill?”
Remarkably, the number one answer was “change energy supplier”. Yet this merely moves the problem from one supplier to another, wasting energy nonetheless.
“A far more beneficial way is to take stock of the biggest consumer of electrical energy in industry today – the electric motor,” explains Andy Preston, UK drives product manager, ABB.
Some 64% of all electricity is consumed by electric motors, yet only about 5% of the installed base use any form of control to regulate the speed of the motor depending on demand.
A variable speed drive (VSD), for instance, can reduce energy by up to 60% or more in most applications and has a payback, often in less than two years, and frequently in less than one year.
A far more beneficial way is to take stock of the biggest consumer of electrical energy in industry today – the electric motor
Andy Preston, UK drives product manager, ABB
“Firstly energy managers need to be aware that VSDs exist. And then a relatively simple energy assessment can identify the applications that offer the biggest energy savings. It really is that simple,” explains Preston. “But a VSD is not just an energy saving device in itself.”
An increasing number of customers are looking at energy management to maximise profitability of existing plants.
Richard Sturt, business development manager for Process Industries at Rockwell Automation, comments: “The first step is to monitor energy usage as precisely as possible. Ideally, energy data is correlated with production data to understand the energy use per unit of production.”
If the plant hasn’t previously had an energy monitoring system, a reduction of usage of 5-10% is not uncommon.
As with any initiative,” says Sturt, “it’s important to obtain the buy-in from everyone involved. If operations staff cannot see the energy bill for their production line or KPIs, it is unlikely that saving energy will be a high priority for them.”
As Sam Thiara, marketing and sales manager for Industrial Energy Solutions Group at Emerson Automation Solutions, explains: “Energy remains one of the largest operating expenses and perhaps the greatest opportunity to improve the company’s bottom line.”
At industrial sites, Thiara says: “up to one-third of energy can be wasted through bad conversion, leaks or other inefficient practices.”
Energy remains one of the largest operating expenses and perhaps the greatest opportunity to improve the company’s bottom line.”
Sam Thiara, marketing/sales, Industrial Energy Solutions Group at Emerson
To improve their energy efficiency and reduce their costs, plant managers need real-time insight into how energy is being consumed and lost at their site.
“An energy management information system (EMIS), such as Emerson’s, makes that possible, and most organisations that commit to these systems will enjoy 5-20% energy savings as a result.
“Measurement supports everything that we want to do around energy management,” adds Thiara.
However, measurement alone doesn’t reduce energy consumption, although it does enable excess consumption to be detected and investigated.
When manufacturers look at their energy performance, it is often in hindsight and is an incomplete picture, with data culled from a variety of sources, such as control systems, electrical monitoring systems and other data acquisition systems.
To better manage site energy consumption and costs, organisations need an accurate way to visualise where and how energy is being consumed.
Once there is a clear picture, this information can be analysed in order to take immediate action on over-consumption events, identify and prioritise energy saving projects, and track improvement over time.
“Most plants today only measure the energy streams in a single point at the source – where water, gas and electricity enter the plant, from the air compressors, from the steam boiler, and, for example, the utilities plant,” explains Thiara.
“Therefore there is no visibility if there are leaks in an area somewhere in the plant, if consumption is higher than normal in a specific unit, or if equipment is running when not needed.”
Since the flow of energy around the plant is measured with finer granularity, the energy manager gets the ability to detect and pinpoint over-consumption and leaks to a certain plant area, unit, or even an individual piece of equipment and investigate why.
“This in turn allows plants to uncover leaks, combustion inefficiencies, and equipment running when not necessary,” concludes Thiara.
Energy management systems are extensive, covering real-time SCADA applications, energy scheduling and accounting, through to transmission security management.
While these systems are invaluable, sometimes checking the energy use of individual process applications can quickly identify easy wins.
Electric motors are the largest industrial consumer of electricity and installing a VSD is often believed to be the most effective energy management method available.
Yet, it is persuading the management that the energy saving potential is available on their applications. This has led to VSDs being loaned to process industries so that they can perform ‘before’ and ‘after’ measurements [pictured: ABB offers a hire or loan drive which is temporarily wheeled alongside the application].
This always shows the energy saving benefits that can be achieved by applying a VSD, particularly to centrifugal loads such as pumps, fans and compressors.
The gains that are available will depend a lot on the process. There may be some simple advantages to be had just by being aware of energy usage, for example switching off equipment that is not in use or understanding peak demands and avoiding them.
“The next stage may involve making modifications to the application software to improve energy usage,” says Sturt.
“Reducing the speed of a pump or fan by 20% can save 50% of the energy usage, so fitting a variable speed drive could generate significant savings.”
In complex multi-stage processes with lots of parameters it’s not always obvious what to do. More sophisticated techniques may need to be adopted, such as model predictive control (MPC) to help analyse and control the process.
“If you are running an old plant it is possible that it hasn’t been designed with the latest energy efficiency concepts in mind. You may need a process redesign and capital investment to make any further gains,” explains Sturt.
For most standard individual pieces of equipment like boilers, compressors and the like, the specialist will know the efficiency of the latest equipment in some detail.
It will be relatively simple to calculate the potential savings in investing in new processes and the expected payback period. Installing an energy monitoring system will help to identify the key areas.
In the future, manufacturers will see more ‘energy aware’ control systems. It will be standard practice for smart devices, machines and process plant to communicate their energy usage in real-time rather than it being an afterthought.
End users will look at energy usage for the equipment they are purchasing and will expect it to reduce consumption compared to previous versions. Demand management will also become more important.
Some large energy users already manage usage in conjunction with their energy suppliers. This will become more commonplace and energy prices could be communicated to users in real-time so that manufacturers can adjust production accordingly.