When the topic is energy efficiency, it always seems to be a case of good news versus bad news. For every ray of hope that we're making progress in managing our energy production and consumption, there appears to be a dark cloud of reality indicating the opposite. Last year when I reported on the release of a technology roadmap by the U.S. photovoltaics industry, I quoted some industry figures to show how far solar-cell technology had already advanced. I noted that two decades of research had reduced the cost of manufacturing a photovoltaic energy system from $4.50/W down to $2.20/W.
Subsequently, I was taken to task by a reader for not mentioning the fine print. Howard Hayden wrote in to say that $2.20/W represents the cost per peak, uninstalled watt. Hayden explained, "Usually, the around-the-clock average power is less than a fifth, often as little as a sixth of the peak wattage. Therefore, to get a meaningful value, you should multiply the $2.20 by at least five. Also, having a photocell sitting on the desk is a long way from having a system that delivers ac electricity to the power lines." These points remind us that projections about energy solutions are often a bit too rosy.
The auto industry provides another case in point. Lately, hybrid electric vehicles (HEVs) have been making headlines. Imports like the Honda Insight and Toyota Prius, with ratings of over 50 mpg, have given us an immediate taste of what HEVs can do to cut fuel consumption. U.S. automakers have been showing off their Partnership for a New Generation of Vehicles (PNGV) concept cars that promise us sedan-size family vehicles with 80-mpg ratings just a few years from now. But this good news is tempered by the current reality.
The EPA recently reported that vehicle fuel economy is now at a 20-year low thanks to increases in the sales of light trucks. These vehicles, which include SUVs, vans, minivans, and pickup trucks, make up almost half of the domestic market for light vehicles today. This category encompasses both cars and trucks with less than 8500 lbs of gross vehicle weight.
The report, "EPA Light Duty Automotive Technology and Fuel Economy Trends 1975 through 2000" (available on the Web at www.epa.gov/otaq/fetrends.htm), has found that average fuel economy for light vehicles declined more than 7% since 1988. This is due to the rising truck sales and the fact that car makers have traded fuel economy for in-creased vehicle weight and performance. With light trucks averaging about 20 to 22 mpg and cars averaging 28 mpg, the average efficiency for all 2000 model light vehicles is only 24 mpg. Keep in mind that these values would be lower in real-world driving situations. That aside, 24 mpg is a far cry from the PNGV's goal of 80 mpg.
Of course, automakers hope that hybrid technology will boost the average fuel-efficiency ratings of their fleets. But given that HEVs are just coming to market now, it will be years before their impact is felt on a large scale. The same may be said for fuel cells and other promising alternatives.
Moreover, comparative situations exist for various types of electrical and electronic equipment. New power technologies promise lower power use for many products, particularly those with electric motors. Adoption of these technologies will be encouraged by green legislation, rising energy costs, and growing consumer awareness. But given the long life cycles of many products already in use, it could be a long road from the successful design of products with better power efficiency to market-wide reductions in energy use.