It's the most noticeable among many features aimed at reducing energy use by the nation's largest traditional grocery store chain. The store also has compact fluorescent lights that require less electricity and last 10 times longer than traditional bulbs. Motion detectors help shut off lights when areas are vacated. The store recycles exhaust to heat water, uses more-efficient plastic fans, and has concrete floors that can be cleaned with water instead of chemicals used for tile.

The grocery business is getting greener, led by initiatives from chains such as Kroger Co. (which operates Smith's groceries in Utah), Wal-Mart Stores Inc. and Tesco PLC. They're part of a broad range of businesses, including giants such as General Electric Co., General Motors Corp. and Exxon Mobil Corp., reacting to increasing public concern about energy issues.

The trend is particularly noticeable among grocery stores, a regular stop for American shoppers.

For grocers, energy savings are part of a critical effort to cut costs and deal with tighter profit margins as Wal-Mart and other discounters build up their grocery aisles.

The efforts make financial and public relations sense, environmentalists say amid annual Earth Day activities.

Kroger, which had $66 billion in 2006 revenues, says energy consumption is down 20 percent since 2000 thanks to efforts ranging from new, more-efficient technology to pushing common-sense steps like turning lights off when not needed. Company officials say it's hard to state a total financial savings because energy prices have been rising, but estimate it at tens of millions of dollars.

''It's a critical cost element that they still have some room to improve upon,'' said Craig Hutson, an analyst at the corporate bond research firm Gimme Credit. ''In an environment where it's intensely competitive from a pricing standpoint, whatever you can do on costs is going to help you generate profits.''

Dave Hamilton, director of the Sierra Club's global warming and energy program, said grocers, with many power needs such as refrigeration, can help their images while saving money.

''Kroger and Wal-Mart and others who are making these changes are definitely winning on the bottom line, as well as starting to have something to show customers that they are doing the things we need to do,'' Hamilton said. He said the chains have also increased organic food offerings because of customer demand.

Food Lion LLC, subsidiary of the Brussels, Belgium-based Delhaize Group, has been an industry leader since targeting energy costs consuming 7 percent to 10 percent of its operating costs nearly a decade ago. Food Lion spokeswoman Kimberly Blackburn said the chain had been looking for ways to reduce overhead so it could keep prices down, and decided to partner with the Environmental Protection Agency in a program to cut energy use.

Food Lion says it has cut energy use 27 percent for its 1,300 supermarkets.

Wal-Mart this year has opened what it calls ''High-Efficiency Supercenter'' stores in Kansas City, Mo., and Rockton, Ill., that use 20 percent less energy than typical grocery-selling supercenters by using innovations in heating, cooling, water, lighting and construction materials.

London-based Tesco, Britain's largest supermarket chain with $85 billion in revenues, in January announced plans to spend nearly $1 billion on a campaign to cut carbon emissions and persuade its customers to buy environmentally friendly products.

''I think saving energy is great,'' added shopper Kathy Dannemiller. ''I don't know that it's making any difference in the prices, but it certainly can't hurt anything.''

Many Kroger stores point out the conservation efforts with signs featuring ''Energy Dude.'' Each Kroger store also educates workers on little things they can do.

''Saving energy is not only good for the environment, it's good for your paycheck. Every dollar we save makes the company stronger, and your job more secure,'' advises a sign in an employee area of the store.

Grocery efforts to get greener

Kroger Co., which operates Smith's groceries in Utah, says it has cut energy use by 20 percent since 2000. Here are some of the steps Kroger and other grocers have taken to get greener:

* Each Kroger store has an ''energy champion'' to lead employee education efforts and look for ways to cut use; there are regular energy-use audits, sometimes using thermal imaging cameras to detect energy waste in cooler cases.

* Kroger is exploring ways to reduce or replace plastic bag use, including in some regions giving money credits for customers reusing bags.

* Whole Foods Market Inc., which plans to soon build a store at Trolley Square, says it is using solar power in some stores, is gradually converting its truck fleet to biodiesel fuels, has a composting program for spoiled produce and other waste, and has bought renewable energy credits from wind farms to offset the electricity used in its facilities.

* Safeway Inc. buys wind energy, covering its electricity needs for all of its fuel stations, its corporate campuses, and its San Francisco grocery stores. The company has gone to high-efficiency bulbs for outside and interior lighting, and launched a comprehensive recycling program.