It long has been recognized that efficient use of process heat is crucial to plant economics. Indeed, when process integration burst onto the scene in the late 1970s, the approach focused primarily on energy conservation and, in particular, the design of heat exchanger networks. Its “pinch” method transformed the design of processes, improving the utilization of heat.
Three decades later, it is clear that plants have plenty of room for improvement in how they use heat. This is underscored by the recent launch by the U.S. Dept. of Energy (DOE) of its “Save Energy Now” initiative (p. 9) that specifically targets inefficiencies in process heating and the use of steam. Jim Quinn, lead technology manager, industrial energy systems for DOE’s Office of Industrial Technologies, Washington, D.C., explains that the program will assess 200 of the most-energy-intensive industrial facilities in the nation, selected from among those that operating companies nominate. He says that chemical plants will likely account for the largest number of these. The evaluations will begin in January with the last finished by the end of 2006, he reckons. A prototype assessment conducted in November at a 3M chemical facility illustrates potential savings; it identified opportunities for replacing steam with waste heat and optimizing combustion.
At each selected site, DOE will provide, gratis, a specialist, who has received training on the use of its free energy-assessment software tools and passed a rigorous examination, to lead a team drawn from the operating company, notes Quinn.
The need for efficient use of electricity also is old news. However, plants still aren’t doing enough. Take their use of motors, for example. Many sites rely on standard efficiency units instead of higher efficiency models. That makes no financial sense, emphasizes Randy Breaux, vice president of marketing at motor-maker Baldor, Ft. Smith, Ark. The capital cost of a motor typically represents only about 2% of the lifetime cost of the unit; a premium motor with 1-3% better efficiency lists for only about 20% more than a standard unit and generally offers a payback of 18 months or less, he says.
Doug Thrift, manager of market research for Baldor, provides a telling example: A 100-hp standard motor (93.6% efficiency) lists for about $6,700. Operating 24/7, it costs over $69,800/yr to run, based on 10¢/kWh electricity. A premium motor (95.4% efficiency) lists for about $7,750. Running continuously, it uses about $68,500/yr in electricity. So, the payback for choosing the better motor is well under one year.
Over and above that inducement, some local utilities offer rebates that will cover most if not all of the cost premium for selecting the more efficient unit, notes Breaux.
Clearly, the tools and technology to save additional energy exist. What has been lacking is the right motivation and mindset. So, perhaps we will find today’s high energy prices a blessing in disguise if they finally prompt some plants to get more serious about energy savings.