Variable speed drives now supported by government

Written by: Jeff Whiting, Mitsubishi Electric | Published:

Engineers have long known the basics of the energy saving potential of variable speed inverter drives. For 20 years they have been promoting their uptake, either as energy efficiency improvers or simply as good practise. Each case needs to be looked at individually, but as a rule of thumb we can say that a drive will payback its capital cost in 12-18 months, then continue saving energy – and therefore money and carbon – for the remaining 5-10 years of its working life. It total, there will have been a substantial saving in both financial costs and carbon emissions.

Given that seventy percent of all electricity is used to power electric motors, drives should be mainstream products that can be installed in many, many application, each contributing to carbon and cost reduction.
But for some reason government guidelines have always fought shy of drives, not recommending them with the enthusiasm that might be expected. Looking closer at the official documents, drives' carbon reduction capabilities are acknowledged but their cost saving potential is overlooked.
Most significantly the Capital Allowances available for 'green' technologies has not been available on drives, effectively discouraging their take up. Even today, probably 80+ percent of motors installed in industry are not fitted with an energy saving drive
This has frustrated engineers at every level. Drives sales engineers have lost contracts, plant engineers have not been able to win approval from their managers to install them, and planning engineers have struggled with bureaucrats and civil servants.
The industry body that has been looking into this is GAMBICA (Association for Instrumentation, Control, Automation & Laboratory Technology), whose staff are supported by senior engineers from all the main drives and automation companies. Their work on drives has been spearheaded by Steve Brambley, Deputy Director, who has interfaced with Government departments and their advisers on this subject for literally years.
It turns out that the government is advised by McKinsey & Company, the international management consultants, who for some reason did not acknowledge the money saving potential of drives until their most recent publication: Pathways to a low carbon economy: Version of the global greenhouse gas cost abatement curve.
As the title suggests, this publication does not have the racing plot line of the latest Harry Potter novel, but it is in its own way an edge of the seat thriller. And like Rowlin's latest, readers really have to know the background to fully appreciate the text.
It is set out like an innocuous management report, starting with a Summary of finding. This states that there is a major international effort to reduce greenhouse gas emissions. It then offers the McKinsey greenhouse gas abatement cost curve, as a tool for assessing the potential benefits of various actions and comparing the results with the expected costs.
A cost curve is a typical tool of management consultants - and let it be said - they are often very useful, condensing complex and multi-dimensional information into a simple two-axis graph. The problem with cost curves is that users know how difficult they are to compile and that management consultants charge a lot for them, so they are pre-disposed to trust them and therefore use them blindly without questioning their accuracy.
In this case Version 1 of the McKinsey greenhouse gas abatement cost curve was well constructed and accurate except for one little omission – variable speed inverter drives!
It is perhaps not surprising that McKinsey let this problem slip through – after all they are typically accountants, not engineers. And neither is it surprising that the government officials accepted the flaw – not many engineering minds in Whitehall.
However, when engineers saw the problem they were up in arms. The only surprise is that it has taken so long for rectification to be addressed.
Significantly in the new Version 2 curve, drives come in right at the top of the ranking, bettered only by a wholesale switch to LED lighting and thermal insulation of commercial buildings. Drives are seen as greener than other industrial efficiency improvements, electricity from landfill gas, biofuels, geothermal and next generation hydroelectricity schemes.
At this point I think it would be nice if the government were to offer an official apology and a top man from McKinsey were to fall on his sword. But that is about as likely as a bank chairman being commended for his moral fortitiude.
Instead, let's look at some details of the report. The analysis finds that if no attempt to curb emission is made, they will grow by about 40 percent by 2030. There is potential, if everyone pulls together, to turn this around to a 35 per cent reduction. This would cost about £200bn annually, or one percent of global GDP, and would hold global warming to just under 2 degrees Celcius, a critical figure if icecap melting and desert growth are to be contained.
The report goes on to define four categories of abatement opportunities: energy efficiency, low carbon energy supply, terrestrial carbon (agriculture, forestry), and behavioural change. Of these energy efficiency has the most promise; it could account for about a third of all potential savings, uses mainly proven technologies and does not rely on changing human behavior.
McKinsey looked at carbon reduction on a global scale, but this is not a scale familiar to most working engineers. They look at a rather smaller world, a single production plant or a machine design, and it's rare when the boss asks for a reduced carbon footprint. The boss wants cost savings, but as McKinsey is finally saying, cost savings go hand in hand with carbon reduction and global problems are made up of many many many smaller worlds


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