The issue of energy efficiency is slowly making its way to the boardroom table. While it is a positive development that the issue has come this far, it has taken a very long time to get here. What is more, few companies seem to know what to do about it.
It’s not because of a lack of knowledge inside the companies. Engineers know that variable speed drives and high efficiency motors can save huge amounts of money. For years we have been talking to engineers who see the benefit of drives, but tell us there is nothing they can do because saving energy is not a priority in the boardroom. The engineer’s job was to keep the plant running – energy could always be bought cheaper by shopping around. But those days are gone and energy prices are not going to go back to where they were.
Because of the low priority the issue has had, it can be difficult to find a dedicated person in charge of energy. The issue used to be deferred to the senior management, who showed scant interest. However at the moment, few investments offer a better return on investment than drives and motors. Typically, you see payback within two years and savings that continue into the future.
The mistakes that lead to energy waste start at an early stage. Motors use 65% of the electricity used in industry, but many users simply select motors on price alone by going for the cheapest option and not looking at the operational expenditure over the life of the motor. As well as causing unnecessary maintenance problems, such motors also tend to have higher energy losses. Secondly, users do not fit variable speed drives where the flow of air or liquid in a system can be reduced, instead choosing the system with the lowest initial capital cost, normally one restricting the flow with valves. Again, this leads to high energy losses, much greater than the capital cost investment.
The water utilities have really woken up to this. A few years ago they started using variable speed drives on a wide scale to improve their processes, but they are now also seeing the energy benefits.
One leading water company is letting its engineers spend £5k a week on minor purchases without consulting senior management. This means that if they can put their finger on a problem, they are also able to fix it.
Another problem is that engineers only have time for emergency work and no time for traditional good maintenance, including a walk around the plant. Recently, one of our engineers investigated an air-handling unit together with a customer, to see if installation of a variable speed drive would be viable. When opening the inspection hatch, they found that the drive belt had perished and the motor was just spinning around. As nobody had noticed deterioration in air quality, the unit was not needed and could be switched off.
Engineers also need training and support. Most drives that find their way onto end users plants are not set correctly for energy savings. Site engineers need to keep in touch with the manufacturer and get appropriate training. During a recent training session at a customer site, the ABB engineer discovered that the flux optimisation feature of an AC drive wasn’t switched on. By enabling this function, the current drawn dropped by 10%, saving £11,000 worth of energy per year.
UK industry needs to empower its engineers and trust their judgement. This will give the most efficient processes and the lowest running cost and ultimately, the best result on the bottom line.