Marek Lukaszczyk examines opportunities for improving energy efficiency in the oil & gas industry
The oil and gas sector is in the spotlight and under increasing pressure to improve its energy efficiency. Thankfully, there are ample opportunities for energy reduction at the processing stage.
As one of the world’s largest consumers of energy, electric motors in oil and gas applications provide a great opportunity to improve efficiency. Historically, the sector has not prioritised the efficiency of its electric motors. In fact, most oil and gas facilities have operated with legacy equipment – with many motors operating for several decades. In fact, until July 1, 2021, hazardous area motors were exempt from the efficiency standards that motors in other applications were required to adhere to.
The new regulations, known as the EC 2019/1781 requirements, are part of the EU goals for sustainability and efficiency. This new rule requires electric motors and variable speed drives to achieve mandatory minimum energy performance standards (MEPS).
Elsewhere, motors are expected to follow NEMA – the North American standard for electric motors. NEMA is the publisher of NEMA MG 1-2014, a book to define manufacturing standard for both AC and DC motors. This standard is relevant in North America and other areas of the world.
Energy efficiency refers to the ratio of mechanical output power to the electrical input. Energy efficiency standards are categorised in International energy (IE) efficiency classes, with IE1 (standard efficiency) indicating the lowest levels of efficiency and IE4 (super premium efficiency) the highest. As of July 2021, when these regulations come into play, all three-phase motors with an output between 0.75kW and 1000kW must meet the IE3 standard, or premium efficiency. This now includes hazardous area motors.
The new rules replace the regulation EC 640/2009 and are expected to bring huge reductions in the energy consumption related to motor use, while maintaining the required level of safety. It is estimated that by 2030, this will deliver extra energy savings of 10 TWh/yr and GHG emission reduction of 3 Mt CO2 equivalent across all industrial sectors.
New legislation will also come into force two years later in 2023. At this stage, motors new to the European market with a rated output between 75kW and 200kW will be required to achieve IE4 efficiency ratings giving greater energy savings. Single-phase motors with 0.12kW power output and above will also be required to meet IE2 levels as a minimum under the new legislation. These rules are relevant in the European market but are expected to set a new standard for motor use across the world.
Appropriate motor sizing can also support energy reduction in oil and gas processing. If a motor is oversized, with the actual load less than 50% of the rated load, it will massively reduce the efficiency of the motor in question. For this reason, it’s important that efficiency and sizing considerations go hand in hand.
There may also be additional factors to bear in mind when choosing ATEX motors for oil and gas applications. As a result of safety requirements, explosion-proof motors (Ex db, Ex dc) may face design constraints such as derating for variable speed drive (VSD) operation or reduced starting current. This may sometimes result in a larger frame size, which could lead to additional considerations when retrofitting equipment with a need for motor interchangeability.
VSDs Or Soft Starters
Very few oil and gas applications require 100% flow continuously, yet many of the motors used in such applications are set at one continuous speed. VSDs can effectively control rotating equipment such as fans, compressors and pumps in industrial processes and offer the best efficiency advantages in variable torque applications. In fact, according to the European Committee of Manufacturers of Electrical Machines and Power Electronics (CEMEP) a 20% reduction in speed could lead to a 50% reduction in energy.
To deliver the maximum energy saving, VSDs must be commissioned and installed correctly. This is where partnering with an expert, such as WEG, pays off. If the VSD hasn’t been properly configured this can have a real impact on the performance of the system.
Similarly, soft starters can be useful when motors are often left idle. Idling motors use energy unnecessarily and should always be shut down if they will not be needed. As the name suggests, soft starters allow the motor to start the load more gradually by limiting the voltage to the motor and providing a reduced torque.
The oil and gas sector has ample opportunities to reduce its energy consumption at the processing stages. Although much of this change is being driven by regulation, the industry must also take responsibility for choosing equipment that can further support this progress.
Marek Lukaszczyk is with WEG