Driving Energy Efficiency

With motors consuming the vast bulk of industrial electrical energy supply, there are obvious attractions in the solutions that can cut bills and boost your green credentials.

Direct and indirect energy costs – be that of electricity, industrial fuels as sources of heat, or transport fuels – account for a good chunk of the outgo of energy-intensive industries, affecting their bottom lines adversely at times. If fuel prices skyrocket and subsidies are removed, energy expenditure would rise sharply to account for a greater proportion of the “cost of production” pie.

Raw materials would also get pricier, considering that each one of them would have consumed energy to be unearthed/refined/fabricated/processed.

The cascade effect affects the final producer and thereby the end-user to whom the costs are passed on. Demand drops and domestic savings rise, recession sets in and the economy stagnates.

Figure 1 depicts the rise in the global energy consumption (all sectors), as documented by the International Energy Agency. The values for 2010 and 2030 are forecasts. The IEA thus predicts a nearthreefold rise in energy demand over the 59-year period 1971 to 2030.

The industrial sector accounts for about 30 percent of the total energy consumption and 40 percent of the total electricity consumption (excluding the power sector, which is the largest consumer of energy fuels in an economy, and supplies secondary energy to the industry). In some highly industrialised First World countries with lesser populations – Finland, Denmark, etc – industry accounts for over half of the total energy consumption in the economy.

Overall, industrial energy consumption is slated to rise twofold in the 59-year period referred to. The OECD countries, which have already managed a reduction of about 8 percent in this regard from 1973 to 2004, even as their GDPs have grown, will succeed in keeping the industrial energy consumption within their national boundaries on a tight leash, assuming a greater deal of relocations of manufacturing bases and capacity offloads to the Third World.

With the OECD nations having latched on to a plethora of energy conservation methods over the years, the Third World countries – India and China especially – are also becoming booming markets for energy solution providers in the First World.

Controlling emissions

Energy consumption and greenhouse gas emissions are coupled to a great extent, though renewable energy sources have lessened the degree of coupling in the last few years. Cost reduction to stay competitive in the global market and emissions reduction to abide by the Kyoto Protocol norms, along with rising energy prices, have created an urgent need to cut down on industrial energy consumption.

Once again, just as pollution control could follow either a “source reduction” or an “end-of-pipe” approach, or combine both these to get the best results, energy conservation may drive industries to replace old and less-efficient motors and other equipment like engines, generators, turbines, boilers, fans, pumps, blowers, compressors, etc, with highlyefficient ones, introduce variable speed drives, and implement process improvement strategies. Or it may make them think on the lines of recovering waste heat from the existing less-efficient devices and reuse the same within the plant.

However, when one combines both these approaches and tries to recover as much heat as possible from minimized losses, the benefits are redoubled. But there is no one-size-fits-all approach, as payback periods may vary from one option to another, making different choices attractive to different industrial setups. Besides, some industries like aluminium smelters for instance incur greater expenditure on energy than others, and may thus prioritize differently.

When one tracks the flow of energy from source to final consumption, from mines to machinery, and wells to wheels, so to say, one is appalled to note that at times, in some developing countries, owing to the irrecoverable losses in transit – the final usable energy is less than 10 percent of the primary energy content in the fuel.

This leads one to realise that a substantial fraction of the energy content is wasted – and while that does not contribute to the boosting of the GDP in any way, it ends up polluting the air and exacerbating the problem of global warming. More damage than development; more problems than progress.

And the fact that fuels are getting pricier and electricity tariffs are rising, does not help either. Growth cannot be curbed, just as the Second Law of Thermodynamics cannot be turned on its head. Entropy will rise, demand will also rise, but what man can do, with some planning and control, through effective management of resources and greater concern for the environment, is to slow down the rate of entropy increase, to decelerate the growth of demand for resources, especially the non-renewable ones.

The lion’s share of the heat and electricity pie remains nonrenewable and polluting at that. Even as countries invest in renewable energy, and industries resort to having their own captive windmills and solar panels, the fossil-fuel part of energy consumption has to be managed efficiently.

If one could think of a 100 per cent renewable energy economy at some distant day in the future, and if this is also 100 percent reliable at the same time, all worries would melt away. But then, that is Utopia.

Metering down motors

Usually, the last but one component in the energy transfer chain culminating in the industrial plant is the electric motor. The motor may drive any among a host of devices, through couplings or speed reduction units like gears or belts.

A train of processes in any industry in the manufacturing sector is sure to include several motors of different ratings. Each of these receives energy from the main supply, coverts it into mechanical energy and transfers it to the driven device, which may be associated with air compression and delivery, process temperature control, machine drives and conveyors, hydraulic power transmission, HVAC, etc.

In all the processes, there are losses within the motors. Suffice to say that the useful energy which is transferred to the device is less than the energy drawn by the electric motor. There are further losses in the distribution system served by the driven devices owing to pipeline/tubing/ducting frictional losses, throttling losses, etc.

When one does a summation of these losses for all the motors and all the downstream equipment in the industrial setup, it turns out to be a substantial portion of the electricity bill – “paid-for-but-not-used” electrical energy.

Getting down to basics, copper windings are used in electrical motors owing to their low resistance to current. However, the copper is never 100 percent pure; the metallic impurities have much higher electrical resistances than copper and hence, augment the I2R losses.

Using ultra-pure copper would tide over this problem, but then as one and all know, copper is scarce and it has been getting costlier over the years. It is not just a question of pure copper but more copper as well in the stator windings to reduce copper losses, which form about one-fifth of the total motor losses. More copper here means increasing the cross section of the copper windings on the stator, bearing in mind that resistance offered by a conductor is inversely proportional to its surface area.

Doing the maths

But just using more of greater-cross-section-purer copper is not enough. An energy efficient motor should have more higher-quality, thinner silicon steel laminations (a cost increment again) as well in the stator in addition to an optimised gap between the stator and the rotor, and closer matching tolerances (machining to closer tolerances would also entail investments in advanced metrology) to reduce the iron losses which account for 50 percent of motor losses.

Stray losses (about seven percent) can be curtailed by redesigning the geometry, while the bearing and windage losses (about one-fifth of the total) can be reduced by simply using a smaller cooling fan. The International Copper Promotion Council of India has put the price of energy efficient motors at about 15 to 30 percent higher than standard efficiency ones, but has also pointed out that owing to lesser impurities in the copper, lowered resistance and thereby less I2R losses dissipated as heat, the operating temperatures are lower and the motors (and also the bearings) while having slightly longer lives, do not necessitate much expenses on maintenance.

As a direct comparison, a 12 kW ABB electric motor of 91 percent efficiency needs 12.5 percent more steel and copper and 10 percent more copper compared to a standard efficiency 12 kW motor of 89 per cent efficiency.

However, its indirect consumption of oil, coal and gas and its contribution to greenhouse emissions throughout its lifetime (8000 hours per year, for 15 years) is 20 percent less than its standard efficiency counterpart. Although it produces about 10 percent more solid waste at the end of its life, with recycling programmes wellentrenched these days, that is not a major concern, at least in the developed world.

Figure 2 (data from the International Copper Association) charts the improvements in efficiencies which are possible with modifications to electric motors. Three different classes of efficiencies are considered: standard efficiency motor; Energy Policy Act (EPAct), 1992 high efficiency motor; and the National Electrical Motors Manufacturers Association (NEMA) premium efficiency motor.

As shown, the efficiency increases with the ratings and the differences among the three sets narrow down progressively as the horsepower rating increases. On average, the efficiency of electric motors used in industry has increased by about three percent between 1997 and 2007.

Many US companies are reported to have adopted EPAct or NEMA electrical motors in the last few years and duly benefited. Figure 3 throws light on the energy savings that can be expected by switching over to higher-efficiency motors.

The total annual savings for a plant can be calculated if the type and rating of the electric motor and the electricity tariff is known. This will enable one to easily find out payback periods for investments in different combinations of electrical motors (case studies abound on the website www.copper.org).

Drives deliver

Matching speed of the motor to the load is also of paramount importance, to ensure that it delivers just what is required. Otherwise, if motors run at their rated speed and keep consuming maximum power, even when the load on them keeps fluctuating, a great deal of the mechanical energy (derived from the electrical input) is not converted into useful work.

This is where variable speed drives (VSDs) come into the picture. They alter the power input to the motor by varying the voltage and frequency of the supply from the fixed mains, after detecting the change in the load on it.

It has been established from experience that matching output of higher-efficiency motors to demand would result in 20 to 50 percent energy savings, a significant improvement to the 5 to 15 percent achievable by resorting just to higher-efficiency motors.

Several millions of dollars may have been saved in worldwide industrial plants, thanks to the incorporation of VSDs in the upstream chain of electric motors. For example, the drives installed by ABB globally reportedly saved over 130 TWh of energy in 2006. Table 1 includes a number of success stories related to drive implementation.

However, while there are positives all around, it is also observed that 37 million small motors (below 2.2 kW capacity) sold annually to the global industry do not have any speed control at all.

Even more savings

With motors consuming about 70 percent of the total electricity usage in industry, aside from introducing high efficiency versions and variable speed drives there is obviously an incentive to look for other savings wherever possible.

Steps that can pay off include hermetically sealing the motors when in dusty and corrosive environments, monitoring coolant flows, periodic maintenance to ensure that equipment surfaces are clean, ensuring continuous lubricant supply, looking to see that belts transferring motion from driver to driven are not loose, that there are no deposit build-ups on the inner walls of pipes and tubes conducting fluids, and so on. In short, losses – leakages of energy in other words – can happen through any nook and cranny of the system.

Downstream of the motors are the couplings, driven devices and the distribution network fed by the driven devices. Having a premium efficiency motor drive a power-hungry pump or blower defeats the very purpose of installing one in place of a standard efficiency one.

While the M2M revolution is slowly embracing the industry, enabling monitoring of performance of machinery and equipment remotely and prompt servicing as soon as aberrations and anomalies are detected, there are some very simple remedies as well, which are often overlooked.

For example, as detailed in Table 1, a salt producer in the UK, just by realising that a fan had been over-designed and replacing it with a fan of a much lesser power rating, managed to save over US$50,000 per year.

And in wastewater treatment plants, blowers tend to run at the same speed all round, consuming energy all the while and aerating tanks, even when most of the oxygen pumped into the wastewater would escape into the air – being in excess of what could dissolve in the water at a given point of time.

Super-efficient motors and good quality blowers are fine indeed, but that is not all. Process control is also very important to make the most of the benefits. Monitoring the oxygen concentration in the wastewater in the tank and controlling the speed of the motor suitably through variable speed drives, to deliver only when required, can save a lot of energy for wastewater treatment plants, even making some of them net energy producers i.e. selling energy back to the grid.

And while motors may indeed be number one big power consumers, lighting (14 percent) and electrical heating/welding (16 percent) should not be overlooked. Equipment-design and installations such as motion sensors to switch on/off lights and fans can also deliver energy savings.

Apart from electricity, some industries consume primary fuels as well – coal, oil, gas, biomass, – as sources of heat energy, or at times to generate their own captive power. Furnaces, boilers, kilns, etc, which burn fuel for heat energy, if designed for efficiency, will go a long way in further trimming overall energy requirements. High quality refractory linings in furnaces to reduce heat losses is just one example.

Dollars & sense

While simple solutions are often known to plant personnel, there are energy solutions providers and consultants out there who are more than willing to help out industries with the best energy-saving options. Apart from big names like Rockwell Automation and ABB, there are many other players in the market staking their claims to small portions of the huge and growing market pie.

Meanwhile, energy audit software tools like PumpSave and FanSave enable companies to calculate the payback periods for investments in variable speed drives, vis-à-vis other alternatives that may exist.

A lifecycle costing/cost-benefit analysis is almost always important as the bean counters in the industry would opt for an energy-saving solution or set of solutions with incremental costs only if the return on investments would be attractive, and benefits would outweigh the costs of maintenance/replacements/operation after the ROI period.

Peter Terwiesch, Chief Technology Officer, ABB, observes that when one considers that the lifecycle cost of a motor is up to two orders of magnitude higher than the initial cost for the drive, the energy-saving argument gets a strong back-up from economic considerations. However, there is also a concern that the benefits may not be immediately obvious to the small and medium scale industries, of which there are thousands the world over, unless of course there is a dramatic fuel price shock.

It is believed by policymakers that loans and subsidies for energy audits and energy efficiency improvements which have been in force in many parts of the world, improve the economic bolster needed for SMEs to invest in “metering down”. For instance, the Danish Energy Agency in Europe offers a subsidy of US$10 per kW for purchases from a list of high-efficiency motors.

It should also be pointed out that the economics are not all that bad, when one factors in the decreasing size, weight and price of AC drives with speed control and associated electronic control equipment against the mechanical alternatives – fluid couplings, gear trains, etc – which not only add to system inefficiencies and maintenance expenses, but are also getting costlier to purchase. Compared to premium efficiency motors, investments in variable speed drives have quicker payback periods, but these two need to be considered together – one is incomplete without the other.

Apart from service providers who provide the muscle and bone for an energy-efficient setup, there are also industry organisations anxious to help their members “identify opportunities for financial savings through elimination of wasteful use of electricity, coal and fuel oil, without affecting the process or quality of product”, as the Confederation of Indian Industry (CII) puts it.

The CII has succeeded in helping over 180 companies across a variety of industrial sectors to reduce both their thermal and electrical energy bills, through energy audits, training programmes, seminars and workshops, as well as reinforce awareness and entrench energy conservation firmly in the industrial psyche.

Regional comparisons

As already mentioned, the Western world has succeeded in trimming down its energy consumption, and the energy use per unit industrial output has also come down significantly during the last three decades. The reasons are twofold – one, the introduction of energy saving measures thanks to developments in production technology and automation tools; and two, the relocation of some the powerhungry industries to the low cost countries.

Figure 4, which illustrates industrial energy consumption for the UK from 1970 to 200 (courtesy Hannah Evans of the Department of Business, Enterprise and Regulatory Reform), exemplifies this trend, with the energy use per unit of output more than halving in the period 1970-2006.

And Germany, France and the Netherlands, which registered annual GDP growths of between two to three percent during the period 1994-2005, managed to keep annual industrial energy consumption almost constant while achieving an improvement in energy productivity similar to the UK.

Although the EU-27 registered a conspicuous increase in GWh of energy consumed in the industry in the that time period, this was mainly due to the eastern transition economies where energy efficiency had not been as key a part of the psyche of decision makers in industry as it has been in the EU-15. Also, industries being relocated to eastern Europe and some of the former CIS countries, which are competing with India, China and the like for investments, is another factor here.

In terms of energy intensity (energy use per unit of GDP, MJ/USD), both Japan and the EU saw a fall in this index from over 3.5 to 1.75, between 1970 and 2000, while the US also succeeded in cutting down from over four to around two, during the same period.

Japan, hemmed in by rising energy prices and several other disadvantages like a high degree of dependence on pricey raw material imports, has led the way in making homes and industries alike, energy-efficient. There are mentions of AC drives having been installed in HVAC systems in homes to match the speed to the need. In Southeast Asia, however, the availability of oil in Indonesia, Malaysia and Brunei may shift the scales towards some laxity in revamping industry with energy-efficient systems.

While data for India and China are not available for comparison, it can be assumed that industrial energy expenditure in India and China has gone up in tandem with the huge increase in industrial output.

The bigger picture

It needs to be pointed out that reducing energy consumption in industry alone is certainly not going to change the bigger picture conspicuously. The buck cannot be passed on to the industry by the other two energy-consuming sectors – transportation and households. After all, industrial production will achieve economies of scale and machine and energy productivity will rise over time. What about the rise in demand for household energy – electricity especially – with the growth in population and the simultaneous growth in purchasing power and urbanization in countries like India and China? As a percentage, more people stay in cities these days, as compared to two decades ago, and the influx continues, even as towns metamorphose into cities. The rise in the demand for power in the entire economy is inevitable. In these countries, it is akin to gearing up for what is imminent and may assume massive proportions in the decades to come.

Figure 5 depicts the players and aspects associated with energy efficiency, security and availability in an economy. Even as the transformation (conversion of energy from one form to the other), transmission and distribution losses are reduced, stepping up the efficiency of motors receiving the electricity for final consumption will augment the energy savings, and enable final utilization of a much-greater percentage of the primary energy.

The losses in the transformation, transmission and distribution steps are around 40 percent for a First World economy. The losses in motors and energy-consuming equipment in industries, the transportation sector and households add on to make the overall losses stand at about 60 percent or more.

Clearly, there are a whole lot of interrelated players in the picture. Egil Myklebust, the Chairman of Scandinavian Airlines, and formerly with Norsk Hydro and the World Business Council for Sustainable Development, captured the essence in a lecture delivered at the Norwegian University of Science and Technology in September 2007 when he stated that it is imperative that “all these players act in the same play on the same stage”. Myklebust believes that “There are three things that are necessary to combat the climate change problem – energy efficiency, energy efficiency and energy efficiency!’

Heikki Vaisanen, Senior Advisor at the Energy Department in the Finnish Ministry of Trade and Industry sees “a real momentum these days in Europe to do more about this”. The EU energy ministers have pledged to improve energy efficiency by 20 percent by 2020, to reduce dependence on fuel imports and to decouple greenhouse gas emissions as much as possible from economic growth. This reduction is slated to result in savings worth 60 billion Euros, according to an ABB report.

The other alternative

It would be apt to note the observation made by ABB’s Peter Terwiesch that energy efficiency is an alternative fuel. Quite like the renewable sources of energy – wind, solar, etc – the base of this alternate fuel needs to be built up as a step-by-step process. It is encouraging to note that the pressure on economies around the world to achieve energy efficiency has risen to a level comparable to the 1970s when the oil shock called for process readjustments, and triggered innovations in the ways manufacturing operations were run.

The bad news, take it or reject it, however, is that time is running out…It seems to be a race against time for humankind. Will a global “Spartanization” help? Can modern man borrow from this Mediterranean lifestyle of yore? But then, it is also contended that desire for prosperity should not be replaced by a fear of the future, and the present generations should not be expected to make compromises to ensure the welfare of future generations.

Ilpo Ruohonen, the Vice President (Technology) of ABB’s low voltage AC Drives department, was quoted as saying that energy efficiency needs to become fashionable to become more acceptable’ across the length and breadth of the global industrial sector.

The good news, as gathered from informal chats with people in the industry and academia, is that energy efficiency is really becoming fashionable, even as economic growth and rise in standards of living cannot (and should not) be stalled. Ilpo Ruohonen, should be glad, just as many others supplying motors, drives and energy efficiency solutions in the global market, will be.

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Figure 5

Table 1

Variable speed drives

Peter Terwiesch, Chief Technology Officer, ABB

Delivering Expert Advice Companies keen to improve on their energy efficiency should know that there is help out there – through services such as energy audits, and by selective implementation of energysaving technologies. S. Ravikrishnan explains.

Energy costs impact the company’s bottom line and getting the most from your energy dollars requires active energy management. Energy needs vary by industry and manufacturing process, according to the ARC Advisory Group. Cost-driven industries, such as metals, paper or chemical plants view energy as a key cost variable whereas reliability-driven industries, including the pharmaceutical and semiconductor sectors, view energy as a quality process variable, requiring reliable energy for acceptable product output. But regardless of industry, energy and demand costs have a definite impact on the bottom line. And increasing competitive pressures, tighter margins and rising energy costs are forcing manufacturers to examine their methods of operation. Evaluating energy usage is one line of action that can reduce costs. Forward thinking companies monitor and manage energy efficiency and utilization by collecting and analyzing data, correlating energy usage with production and managing the effects of weather and other variables. And as manufacturers make a concerted effort to understand where, when and how much energy their operations are consuming, help is available through services such as energy audits and through technologies including power monitors, drives, application software, communication and visualization software. Areas covered by energy management initiatives typically include: • Energy accountability • Power quality • Heating, ventilating, air conditioning & refrigeration (HVACR) control • Auxiliary plant equipment Energy Accountability Energy accountability involves the steps of monitoring, analyzing, and controlling energy usage, with the overall aim of reducing overall energy costs. Energy data is transformed into valuable information that can be used to analyze and understand how energy dollars are being utilized. The derived information can support procurement and rate negotiations; to justify operational and/or capital investment projects to reduce energy costs; to start an energy management program and select “quick hit” projects; identify opportunities for demand control; and verify utility bills. Power quality Electric power solutions are designed to gain advanced control and minimize costs related to energy supply to the facility. Avoiding excess charges by reducing peak demand, lessening the impact of utility power outages, reducing power factor penalties from the utility company, and mitigating the negative effects of poor power factor or high harmonic content are some of the potential benefits. In one real-life example, an oil refinery faced challenges of poor quality and instability of the country’s electrical power supply. Frequent power disruptions and outages meant that the refinery was unable to keep up with increased market demand for its products. A solution was developed to allow synchronization of the refinery turbine generator with the local utility grid. Collecting voltage, current and power-factor data enabled automatic calculation of tariffs on power generation, to impact decisions about effective, fast-acting load shedding for the entire plant. Rockwell Automation supplied the Load Management System comprising of power monitors, PLCs, supervisory system including the application software. With implementation of the solution, the refinery was able to cut energy costs by 27 percent and also derived additional annual savings of US$136,000. In another case, a steel plant’s power supply was being managed by an unreliable, obsolete system that created unnecessary furnace delays, reduced productivity, and a monthly electric bill typically exceeding $2.5 million. With the demand portion evidently presenting an attractive financial opportunity for better energy management/cost recovery, a solution was developed to analyze and optimize production as well as the associated energy consumption. Using electric meter pulses, demand is projected and electric furnace loads shed only as needed. Furnace operators make system selections based on the new demand forecast, allowing greater productivity while reducing electrical costs. Steel production was able to be increased by reducing furnace delay by 78 percent, and the solution paid for itself in less than six months. HVACR control In the Heating, Ventilating, Air Conditioning & Refrigeration arena, providing advanced control of HVACR systems allows for greater flexibility and lower total cost of ownership. Solutions are ideally suited for industrial users where HVAC control is process critical i.e. necessitates tight control of process parameters. Specifically, the control of temperature, relative humidity, differential pressure, and particle count is very important in this area, and controls can be developed for air handlers, fume hoods, central plants, and centralized scheduling and monitoring. HVACR solutions can help to maintain specific temperature and humidity levels to insure product quality; control static pressure to prevent contamination; and to reduce energy costs associated with large air handlers and chillers. Auxiliary plant equipment Here, the solutions encompass methods and algorithms to optimize energy systems for a variety of utility equipment, such as air compressors, chillers, cooling towers and boilers, with the aim of reducing energy costs associated with production of hot water, chilled water, steam, compressed air, and/or refrigeration. Compressor and Chiller Control solutions involve an interface to chillers and associated equipment such as cooling towers and pumps to optimize performance. Efficiency is improved by identifying and reducing wasted energy during periods of lower energy cost. Burner Management & Combustion Control solutions are typically responsible for safe startup, operation, and shutdown of the combustion processes for boilers, ovens, kilns, smelters, furnaces, dryers, process and heaters, single or multiple burners, and single or multiple fuels. These solutions comprise the safety and control systems associated with the combustion process In one application, a sugar producer was using its waste energy to produce power by burning the sugar cane bagasse in boilers to generate steam. The company was looking to get higher efficiencies in all areas of the plant, including steam, heat, water and electricity. After analyzing the situation Rockwell Automation’s solution included installation of a medium voltage motor and variable frequency drive. The result: lower harmonics generation, higher efficiency, less space requirements, longer drive-motor distances, and higher reliability. The solution had major impact on the operations with 100 percent reliability during milling season. Steam consumption was reduced by 66 percent to create equivalent power. And payback was achieved in six months from implementation. variable speed drives

S.Ravikrishnan is Director, Asia Pacific - Power and Infrastructure, Rockwell Automation. The Power and Energy Management Solutions (PEMS) business offers a portfolio of services including plant energy audits, consulting, engineering and applied energy systems.