Power Down: Cut costs with field-ready energy management tips
Written by Andre Voshart
Continuous service and efficiency are two energy issues that are ever present in the resource sector, and making reliable power available anywhere - and at any time - is a priority for those responsible for operations and maintenance in oil sands, oil fields or mining locations across Canada.
Unplanned interruptions due to electrical system faults or power outages can generate heavy losses: loss of production, loss of services, dangerous shutdowns, expensive energy intensive restarts and overall loss of revenue. Unfortunately, utilities do not always supply electricity at the level of reliability and availability required by many applications. Electrical networks are constantly affected by disturbances. They have to be managed efficiently depending on the acceptable levels of energy interruptions in each area.
Governments are also recognizing the potential for energy efficiency. Many are introducing energy-efficiency and carbon-reduction programs, which encourage large energy-using businesses to improve their energy efficiency by identifying, evaluating and reporting publicly on cost effective energy savings opportunities. To achieve this, companies must have a clear understanding of their current energy use, and therefore require tools that will empower people to make decisions.
Following are important areas where energy management techniques can be implemented:
Manage Electrical Assets. Perform regular maintenance and modernization of the electrical network throughout its life cycle. This is required to efficiently deliver a reliable energy.
Monitor Usage. Reducing electricity costs will boost the bottom line, but without the data, you cannot manage energy costs effectively. Domenic Capobianco, a product specialist with Carlo Gavazzi Canada, said it’s estimated that 30 percent of all business downtime is related to a power quality issue of some sort, such as power sags, swells, transients, harmonics and more.
“Sub-metering is the best way to give you an accurate indication of how and where you are using the energy within your facility,” he explained. “It also gives you the information to begin and sustain an energy management program for your business.”
Such meters can be installed either on the main incoming to determine plant-wide performance or in different departments to determine areas of excessive energy use - and even down to individual pieces of equipment to determine efficiency before and after an upgrade.
Moreover, electrical-disturbance monitoring, alarming, event logging and power quality analysis can help track power-quality-related conditions and provide immediate alerts to personnel to impending availability problems. If an event occurs, the solution enables users to quickly troubleshoot the problem and therefore get their processes back up and running quickly.
Reduce Effect of Disturbances. Either during the design phase or during operation, it is often necessary to install equipment to mitigate the effects of disturbances (internal or external, constant or occasional):
Some equipment - such as drives, inverters, uninterrupted power supplies, arc furnaces, transformers, filters and discharge lamps - generate voltage distortion or harmonics. Harmonic filtering reduces and eliminates the harmonics that stress the electrical network, cause outages and potentially reduce equipment reliability and electrical device life span.
For critical application continuity, it is key to reduce the impact of power outages. Therefore, strategies involving maintaining or ensuring power to critical loads are used. They include critical power architectures based on relevant equipment (backup generation, uninterrupted power supplies, redundant systems, etc.). They can be designed and installed by specialists.
Forecast Usage. As well as energy reduction, companies struggle with the prediction of energy use and are often penalized for under or over forecasting. When failing to meet a forecast incurs monetary fines, tracking energy consumption against forecasts becomes important. Mining and mineral processing companies need to accurately forecast energy consumption and have timely access to actual energy consumption so decisions can be made. Complex tools are available to better forecast energy use, but it is also important to take into account the context of excessive energy use and the historical and future production data. According to Schneider Electric, mining and mineral processing companies are investing in meters and enterprise energy management software to monitor and visualize/report on energy use.
Improved forecasting can provide two advantages:
1. Reduce costs.Maximize the use of existing power infrastructure capacity and avoid overbuilding power infrastructure by having more accurate information.
2. Reduce “spinning excess.” If a mining site requires approximately 1.8 MW of power and its dedicated power plant (run by a 3rd party) produces 2.7 MW, there is a spinning excess of 0.9 MW. The company only pays for the 1.8 MW but has to pay for maintenance and fuel for the 2.7 MW. If sufficient information was known about why the peak loads occur (for example, the starting sequence for the mills), the spinning excess could be reduced, therefore reducing the fuel and maintenance costs. Energy events may also be the reason for the size of the spinning excess. A better understanding of their root cause and prevention may also support the reduction of costs associated with spinning excess.
Control Pump and Fans. In industry, 70 percent of electrical consumption is used to turn motors. Of these motors, 33 percent of them control pump or fan applications. Dale Murao, a variable-speed drive product expert with Schneider Electric out West, explains why power issues involving pumps and fans can cost companies energy and reliability:
• If there are belts, gear reducers, pulleys and more when equipment starts, the torque can cause premature wear and stress. • Large to very large horsepower equipment would have a very difficult time to start up while causing voltage sags (lights dimming and other devices may drop out), so other methods of startup are available and recommended. • A poor power factor will create a burden to the utility and they can charge a penalty. (See Devon case study.) • When these motors turn on and off during operations, depending upon the day or time, the customer’s peak-demand meter gets triggered and could charge premiums.
“Variable-speed drives can reduce and also limit inrush currents during startup,” Murao says, by using the acceleration and current-limit modes in the VSDs. “By reducing the inrush, this alone can reduce the mechanical stress of the operating equipment. … Energy efficiencies through VSDs can lead to Cost Savings and prolong the life of the equipment being operated.”
He also says that facilities that have a limited supply of electricity may review existing pump and fan applications to determine what the payback period and the energy savings would be if a VSD was installed. “Other utilities offer incentives for reduction, and depending upon some provinces, there is now a carbon-footprint rebate,” he adds.
Taking Work Home. Some companies are also offering employees incentives to reduce consumption at home, too. Cenovus Energy, an integrated oil company in Calgary, believes everyone plays a role in improving energy efficiency, which is why it implemented the program.
“Every little bit counts,” Cenovus spokesperson Rhona DelFrari says. “The Cenovus employee energy efficiency rebate program offers up to $600 per employee each year as rebates on a variety of energy efficient products, from furnaces, water heaters, fridges and air conditioners to LED Christmas lights and home energy evaluations.”
Every little bit counts.
André Voshart is the editor of REM. The article includes files from Schneider Electric.
