Energy Management How to Reduce Total Cost of Ownership for Oil and Gas Pumps

| Editor: Dominik Stephan

The oil and gas sector accounts for a major share of world energy supply; however, there is considerable energy consumption within this industry itself making it one of the most energy-intensive industries. Owing to this very reason, the sector also has a huge potential for energy savings. Here’s an overview of how to reduce energy consumption and increase cost savings.

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Proper maintenance practices undertaken for pumping systems can bring in cost efficiency
Proper maintenance practices undertaken for pumping systems can bring in cost efficiency
(Picture: Schneider Electric India)

Electric motors account for a major share of electricity consumption in the oil and gas industry. The main applications for electric motors are pumps, air compressors and fans. Of these applications, pumps account for maximum percentage of electricity consumption by far, further emphasizing the energy saving potential. In fact, energy cost represents 40 per cent of the total cost of ownership (TCO) of a typical pump. It is possible to reduce the TCO by at least 30 per cent through appropriate energy management practices.

Introducing the Three–Step Energy Management Plan

A three-step energy management plan can ensure reductions in pumping system TCO with limited investment while maintaining sustainability objectives in the sector. It includes:

  • Energy efficiency management
  • Asset management
  • Energy cost management

Understanding Energy Efficiency Management

Talking about energy efficiency management, it is necessary to understand that most of the inefficiency in pumping systems used in the oil and gas sector comes from two main factors–undersized and oversized pumps, and improper use of throttling valve technologies. Figure 1 shows a comparison between two installations: one with variable speed drive and other with a fixed speed throttling system.

Figure 1: Variable Vs Fixed Speed
Figure 1: Variable Vs Fixed Speed
(Picture: Schneider Electric India)

At a fixed speed for the throttled system, it is necessary to add a throttle valve in the hydraulic circuit. This will modify the system curve. However, the speed remains the same, so the pump curve does not change. The flow rate is matched but the head is much higher than required resulting in poor energy savings.

If an electrical variable speed drive is deployed, then the system curve does not change. The pump curve is modified according to flow speed and affinity laws. Adjusting the speed matches the process requirement and results in significant energy savings. In order to improve the efficiency of the system, a system assessment must be conducted; the flow must be changed from fixed to variable via a variable speed drive, and the pumping efficiency should be monitored. The variable speed drive is a key enabler for energy efficiency in pumping systems.