Saving Energy: More Important Now Than Ever - and Easier
Wed, 01/03/2007 - 7:34am
According to the Department of Energy U.S. industry consumes 32.6 quadrillion BTUs or 9.55 PWh per annum. Here are some energy-saving tips that can go right to your bottom line.
1. Motor efficiency.Motors account for 2/3 or 33.6% of all energy consumed in the country. The two simplest ways to save energy used in motors is to 1. use efficient motors, such as NEMA Premium efficiency motors, for example; and 2. control motors driving centrifugal loadsfans, blowers and pumps. Controlling flow with dampers or valves wastes energy proportional to the product of the flow rate and the pressure drop. The flow produced by a centrifugal device is proportional to the square of the speed and the power required is proportional to the cube of the speed. To reduce flow by 10%, reduce the speed by 5%, which will cut power use by 15%. If the required flow is constant and is less than the pump or blower’s capacity, reducing the speed by changing a drive pulley is an inexpensive fix. If the required flow is variable, install a variable-frequency drive. It’s also important to use the right size motor. While an overloaded motor soon fails, an underloaded motor is often inefficient, even though it may last a long time.
2. Stop those leaks.Compressed air is expensive, and that expense comes from both normal use and leakage. This type of leak can waste $50,000 or more of compressed air. Fortunately advice and assistance are available, and these can pay off. A free software package called AIRMaster+ provides information on assessing compressed air systems, including modeling, existing and future system upgrades, and evaluating savings and effectiveness of energy efficiency measures. It, along with other useful software, is available for download at the DOE’s EERE Best Practices Web site.
3. Check out government programs and utility incentives.The Department of Energy has numerous programs and initiatives to help both government and nongovernment users save energy. The introduction to the Federal Energy Management Program (FEMP’s) Operations and Maintenance Best Practices Guide (Fig. 1) points out that O&M measures generally cost little or nothing to implement, can have immediate paybacksaving an estimated 5% to 20% on energy billsand are administratively simple to put in place.
|Fig. 1: The introduction to the Federal Energy Management Program (FEMP’s) Operations and Maintenance Best Practices Guide points out that O&M measures generally cost little or nothing to implement, can have immediate payback — saving an estimated 5% to 20% on energy bills — and are administratively simple to put in place.|
|Fig. 2: EERE’s Industrial Technologies Program works with industry to develop energy-saving strategies that it then makes available for purchase from the companies that have developed them.|
EERE’s Industrial Technologies Program works with industry to develop energy-saving strategies that it then makes available for purchase from the companies that have developed them. As of July of this year there were technologies available for the aluminum, chemicals, forest products, glass, metal casting, mining, petroleum refining and steel industries. A report on the program (Fig. 2) is available at http://www1.eere.energy.gov/industry/bestpractices/pdfs/itp_successes.pdf.
Many local energy utilities have programs to aid users in energy savings, including rebate programs, workshops and training, demand response programs, self-generation and incentive programs. A comprehensive database of state, local, utility and federal incentives that promote renewable energy and energy efficiency is available at www.dsireusa.org.
4. Use consultants.Some are free. Energy-saving consultants can assist companies in identifying areas where they can save energy. Such consultants are available for a fee, but for some years now there has been a source of consultation available that costs nothing. The program, sponsored by EERE's Industrial Technologies Program, is built around 26 Industrial Assessment Centers (IACs) based at universities around the country and is open to plants with annual energy costs between $100,000 and $3 million. Assessment teams of engineering faculty and students from a participating university make a plant visit to identify potential savings opportunities for efficiency improvements, waste minimization and pollution prevention and productivity improvement; they then make recommendations that, according to EERE, have identified an average of about $55,000 in potential annual savings for each manufacturer, with a payback period on implementation of 12 months on average.
The assessment teams are staffed by “engineer faculty and upper-level engineering students,” says Michaela Martin, technical lead, EERE Industrial Assessment Centers, and they’re not just college kids on a field trip. “Most of our directors are either PEs or they’ve been doing these assessments for 15, 20 years,” she says, “and our students are really outstanding; they are often recruited by the plants they conduct assessments for. Right now we just can’t get them graduated enough for the demand.” Information about the program is available at www1.eere.energy.gov/industry/bestpractices/iacs.html.
Another program, DOE's Energy Savings Assessments (ESAs), provides cost-shared assessments to large energy consuming plants, adds Martin, defined as those with energy bills between $3 million and $100+ million. These assessments, she explains, are done by “qualified specialists, who are actually consultants that have taken an exam administered by DOE in the different technology areas.” These same specialists, she adds, are also available for hire on their own. “My guess is that a lot of people will use these consultants in their programs as well.” This year, adds Martin. “they’re adding electrotechnology, so they’re adding compressed air and pumping. Last year it was just focused on natural gas.” The program’s current round closes January 19, so there is little time left to apply for this year, but now might be a good time to start preparing for the next round. Information is available at www1.eere.energy.gov/industry/saveenergynow/.
5. Consider solar energy.Long dismissed as economically feasible only where mains power was unavailable, decreasing cost (and the availability of incentives offered by state and local governments and power companies) is making solar power more attractive. In parts of the West and Southwest solar has become the hot new thingespecially in California where abundant sunshine, high electric rates and a history of unreliable power have convinced an increasing number of businesses to install photovoltaic arrays, which can trim annual energy bills but not eliminate them entirely. “For industrial users,” says Martin Roscheisen, CEO of Nanosolar “solar is about peak shaving. Typically your off-peak rates are dirt cheap, but in the on-peak times, in the summer especially, [it] can become quite expensive, and that’s where solar kicks in; it allows you to reduce the use of the most expensive electricity.”
|Fig. 3: Part of the 904 kW solar power system on the roof of FedEx Expresse’s Oakland Airport international hub.|
Take small steps.While energy-conservation methods such as high-efficiency motors, variable-speed drives, and high-efficiency lighting can save energy and money, there are savings to be had in small things. Probably the simplest way to save energy can be summarized by the motto “If you’re not using it, turn it off.” This means turning off lights when no one is there (motion sensors can help here). It means turning off motor-driven equipment when it’s not being used. It means not letting computers run when not in use. UPS, for example, has installed "sleep" software on 11,000 of its computers, saving almost $145,000 per year.
|Fig. 4: Nanosolar, Inc. (Palo Alto, CA) has developed a way to make large quantities of thin-film solar cells at low cost using nanoparticles of CIGS (copper indium gallium diselenide) in a process similar to printing. (Photo: Nanosolar, Inc.)|
Another simple step is to sequence equipment in stages: If the load on fluid-handling system varies, for example, consider installing a small pump or blower along with the existing one; when the load is light, run the small unit; when the load increases, run the larger one, or both.
It’s even possible to extract power from pollution control efforts. In 2003 Ford Motor Co. installed a system that concentrated VOCs from the paint booths at its Rouge works, ran them through a reformer to yield carbon dioxide and hydrogen and then fed them to fuel cells that generated 5 kW of electric power. A second installation, this one at the Michigan Truck Plant in Wayne, replaced the fuel cells with a Stirling engine-powered generator to produce 55 kW.