Legislating for greater energy efficiency
27 September 2011
Suzanne Gill reviews an IEA whitepaper which called for greater system-based energy efficiency legislation.
A whitepaper, produced by the International Energy Agency (IEA) earlier this year, argues that energy usage on electric motor applications is going to double by 2030, as a result of the anticipated need for more installations across the globe. However, its suggests that current energy usage could be cut by 10%, despite this increase, if all appropriate efficiency measures were put into place to control new motors.
The paper – Energy-efficiency policy opportunities for electric motor-driven systems - presents the findings of the first global analysis of energy consumption in electric motor-driven systems (EMDS) and the options to reduce it. The document assesses the energy currently used by EMDS and the potential for energy savings, examines market barriers to the adoption of energy-efficient solutions, and reviews current policy settings and outcomes. It then goes on to propose a package of policy recommendations designed to help governments tap the potential for energy savings in EDMS.
Electric motors and the systems they drive are the single largest electrical end-user, consuming more than twice as much as lighting. It is estimated that EMDS account for between 43% and 46% of all global electricity consumption, giving rise to about 6,040 metric tonnes (Mt) of CO2 emissions. The industrial sector consumers 64% of all EMDS electricity. According to the report, without comprehensive and effective energy-efficiency policy measures, energy consumption from electric motors is expected to rise to 13,360 TWh per year and CO2 emissions to 8,570 Mt per year by 2030.
The largest proportion of motor electricity consumption is attributable to mid size motors with output powers of between 0.75 kW and 375 kW. Many different motor technologies and design types are available, but asynchronous alternating current (AC) induction motors are most frequently used and consume the most energy.
Large electric motors, with more than 375 kW output power, are usually custom-designed high-voltage AC motors assembled within an electromechanical system on site. They comprise just 0.03% of the electric motor stock in terms of numbers, but account for about 23% of all motor power consumption, making them significant consumers of global power (about 10.4%). However, they are not currently subject to minimum energy performance standards (MEPS) in any part of the world.
In all electric motor-driven systems some energy losses occur in the motor itself, but energy losses are greater in the rest of the mechanical system to which the motor is coupled. A typical electromechanical system involves a motor, an electrical control system, a variable-speed drive (VSD) and a mechanical load. For any given power rating, there is a difference of only a few percentage points in energy efficiency between average motors and the most efficient motors on the market.
Despite being slightly more costly to purchase than standard motors, higher-efficiency motors (HEMs) with over 1, 000 hours of operation per year are more cost-effective over the system life for end-users in all applications, because motor-energy costs typically account for over 95% of a motor’s life-cycle cost. The internal rate of return (IRR) from the use of a HEM, compared to a standard motor, is often well over 100%, but end-users rarely demand HEM applications, for a variety of reasons. The IEA argues that mandatory regulations are the best way to ensure significant and timely market penetration of HEMs.
The whitepaper found that using the best available motors will typically save between 4% and 5% of all electric motor energy consumption. Linking motors with electromechanical solutions that are cost-optimised for the end-user will typically save another 15% to 25%. The potential exists to cost-effectively improve energy-efficiency of motor systems by roughly 20% to 30%, which would reduce total global electricity demand by about 10%.
The three major routes to achieving these savings include the use of properly sized and energy-efficient motors; use of adjustable-speed drives, where appropriate, to match motor speed and torque to the system mechanical load requirements, making it possible to replace inefficient throttling devices and, in some cases with ‘direct-drive’, to avoid wasteful mechanical transmissions and gears; and optimisation of the complete system, including correctly sized motor, pipes and ducts, efficient gears and transmissions, and efficient end-use equipment to deliver the required energy service with minimal energy losses.
Without policy intervention, the IEA says that it will be difficult to realise these savings in the current market environment because there are too many barriers in place. In unregulated markets, purchasers tend to underinvest in higher-efficiency options and choose electric motor systems with a low first cost. To overcome these barriers, many countries have adopted MEPS for the main class of industrial electric motors. This has been shown to be practicable to implement and is a cost-effective means of saving energy. The average energy efficiency of new motors in countries applying MEPS is notably higher than in countries without such requirements. It is estimated that if all countries adopted best practice MEPS for industrial electric motors, by 2030 approximately 322 TWh of annual electricity demand would be saved, giving rise to corresponding savings of 206 Mt of CO2 emissions.
However, even larger savings could be gained if all EMDS were properly optimised. This objective is less straightforward from a policy perspective, but it is possible to make headway in the more complex domain of EMDS by carefully segmenting the applications in which motors are used, and by targeting regulatory policies at packaged motor systems applications with large savings potentials, says the IEA. It is practicable to set MEPS and energy labelling requirements for a range of core motor-driven systems, including fans, pumps and compressors. In some cases, similar MEPS can be applied to entire motor-driven system applications.
The IEA believes that regulatory measures should not be confined to devices and components that directly consume power - policies could also target the potential energy savings from improved energy performance of mechanical components, such as gears and drive belts. Certain common technologies are fundamentally inefficient and could potentially be regulated out of the market in favour of more efficient options.
As some aspects of motor-system energy use do not lend themselves to simple regulatory approaches, softer policy measures would be beneficial. It is especially important to strengthen market awareness through educational efforts targeting multiple decision-making levels. This would include user-friendly technical assistance through enhanced technical standards, system specification and operational/energy management tools and services. There is also a need to better align fiscal and financial incentives throughout the value chain, which could be complemented by well targeted economic assistance to encourage the uptake of energy-efficient EMDS.
A copy of the white paper can be downloaded from the IEA website: www.iea.org/papers/2011/EE_for_ElectricSystems.pdf
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