Calculator quantifies motors' carbon footprint

An ABB Automation Tech (Drives and Motors) product story

Edited by the Engineeringtalk editorial team Jul 16, 2008

Using variable speed drives to control motors is the easiest way to make a radical cut in electricity consumption.

ABB has released an online calculator that will help users minimise the carbon footprint of industry's largest user of electricity, the electric motor.

The calculator shows how much the carbon footprint can be cut back by reducing the speed of electric motors with variable speed drives.

"There are already many carbon calculators around but none, as far as we know, that addresses this huge area of energy use".

"The possible savings can be very substantial - reducing the speed of motors with variable speed drives can frequently save over 50% of the energy used and in extreme cases by as much as 90%, without any detriment to the application" says Steve Ruddell, General Manager, Drives and Motors, at ABB.

An estimated 11 million motors, with a total capacity of 90GW, are installed in UK industry.

On an average industrial site, motor systems account for two thirds of the electricity used.

They are responsible for about 40% of the UK's total electricity consumption.

"Quantifying the carbon footprint helps organisations manage their footprint and reduce emissions over time".

"But motor energy use is frequently overlooked, despite being the largest area of electricity use in industry".

"Our new calculator aims to plug a huge gap in the market", Ruddell says.

Motors are used in a range of applications, dominated by pumps (32% of industrial motor energy consumption) and fans (22% of industrial motor energy consumption), two application types capable of achieving large energy savings under variable speed control.

Many other applications can also benefit from the improved efficiency possible with variable speed drives.

Despite this, only about 3% of motors are equipped with efficient speed control.

Using variable speed drives to control motors is the easiest way to make a radical cut in electricity consumption.

Most motors are oversized to cope with a maximum demand that rarely or never occurs.

The variable speed drive brings the motor speed down to match the actual demand.

Considerable energy waste occurs when the flow powered by a motor is reduced with traditional control methods, such as valves or dampers, to match the demand.

On-off control is another commonly used method but this results in poor control, irregular flow and considerable start-up current.

The variable speed drive is the only method that directly controls the flow at source, by varying the speed of the electric motor.

ABB's calculator lets the user know how much their carbon footprint could be reduced by equipping a particular motor with a variable speed drive.

The motor rating is defined by the user.

The calculator shows the energy savings in kWh, the monetary savings, the CO2 savings, the cost of a suitable drive and the payback time.

The carbon savings are translated to car and air miles for convenience.

The user is also shown the monetary savings from the energy reduction and a payback time for the chosen product.

"If you want to make drastic cuts in electricity consumption, you can't overlook drives, whether you are running a process plant, an office complex or a retailing operation", Ruddell says.

"For example, one of our customers recently installed drives on two pumps, replacing two fixed-speed starters".

"The motors were rated at 30kW but once under drive control, the energy used was only 6.7kW.

Electricity costs, originally GBP 18,000 annually, were reduced by 75% or GBP13,600".

"As the drives only cost GBP 9000 to purchase, payback was seven and a half months".

"This installation saves 80.17 tonnes of CO2 per year, equivalent to flying back and forth from London to New York 62 times or driving 309,000 miles per year".

"This was a relatively simple measure for the company to take - think of the effort that would have been necessary to reduce the mileage of their car fleet by 309,000 miles annually".

"Similar savings are achievable in many other industries".

"Drives are easy to install and can be added to existing plant".

"Because they save energy, there is no long-term cost - on the contrary, they make a positive contribution to the bottom line".

"With ABB's new carbon calculator, savings with drives are easy to quantify".

"It will be difficult to achieve equally impressive savings with any other method", Ruddell said.