20130207-094217.jpgBy now, you’ve surely heard about the environmental impact of food waste. But the scale of the problem is not as well known. In a recent report, the Natural Resources Defense Council came up with these admittedly inexact but eye-popping numbers:

Getting food to our tables eats up 10 percent of the total U.S. energy budget, uses 50 percent of U.S. land, and swallows 80 percent of freshwater consumed in the United States. Yet, 40 percent of food in the United States today goes uneaten. That is more than 20 pounds of food per person every month. Not only does this mean that Americans are throwing out the equivalent of $165 billion each year, but also 25 percent of all freshwater and huge amounts of unnecessary chemicals, energy, and land. Moreover, almost all of that uneaten food ends up rotting in landfills where it accounts for almost 25 percent of U.S. Methane emissions. Nutrition is also lost in the mix—food saved by reducing losses9 by just 15 percent could feed more than 25 million Americans every year at a time when one in six Americans lack a secure supply of food to their tables.

The problem is getting worse, not better. Jonathan Bloom, a journalist who has become perhaps the world’s leading on food waste, notes in American Wasteland: How America Throws Away Nearly Half of Its Food (and What We Can Do About It) that the typical American now throws away his or her body weight in food each year and says:

Ominously, Americans’ per capita food waste has increased by 50 percent since 1974.

I’m a hawk when it comes to food waste. I’ve never considered the appearance of mold on a hunk of cheese reason to throw it away. I make batches of turkey soup from Thanksgiving leftovers. My children used to call me “the human garbage pail” because I scarfed up uneaten food from their plates. I was unembarassed. I almost find it painful to throw food away.

But personal vigilance alone will not solve the food waste problem, so I’m pleased to report that a couple of California entrepreneurs have come up with plan to reduce waste at a key juncture on the road from farm to table. Stuart Rudick, an investor in health and wellness businesses, and Anthony Zolezzi, a consultant, entrepreneur and author, have started a company called Food Star Partners, which uses a mobile phone app to alert supermarket customers when perishable produce is going on sale.

The idea’s simple. Essentially, when a supermarket has too many carrots or bananas or mangos on hand, it can send out an alert via social media, text message or email to customers, alerting them to a flash sale of produce at a very low price. The store generates extra revenue; the consumer gets a deal; food is kept out of a landfills and greenhouse gas emissions are curbed.

As always, the execution is where things get complicated.

The idea to tackle food waste came from Zolezzi, who previously started the recycling system Greenopolis which was sold to Recyclebank. Anthony is a regular at FORTUNE Brainstorm Green, and he is always brimming with ideas. His method, he told me, is to think of a big environmental problem, and then isolate himself to dream up solutions. Last year, he decided to focus on food waste.

“I just sat down for three days with nobody around, and said, how are we going to solve this?,” he said.

He came up with a variety of grand schemes, and when he took them to Stuart, they decided to begin by focusing on single element of the problem–food thrown away at retail, which is mostly produce.

The opportunity for savings is significant: The U.S. Department of Agriculture estimates that supermarkets lose $15 billion each year in fruit and vegetable losses alone.

So what’s the obstacle? First, the retailers themselves don’t tend to view food waste as a problem. Instead, they plan for it.

“For the last 20 years, they’ve budgeted 12 or 13 or 14 percent shrink. So long as it doesn’t go above that, they don’t have a problem,” Anthony said.

Besides that, supermarkets are reluctant to sell less than perfect fruits and vegetables, even if some of their customers would be willing to buy them.

“They think that their brand is sacred,” Stuart said. “Brands don’t want to sell melons that are potentially going to mar their image or cannibalize another sale.”

20130207-185353.jpgRecently, though, Food Star Partners signed up its first supermarket chain–a small group of stores in Northern California called Andronico’s, as Dana Gunders reported on her NRDC blog. She tracks the rescue of apples that weren’t quite red enough or big enough to be sold as conventional Fancy Grade apples, but were put on a special sale by Andronico’s and Food Star Partners. An Andronico’s exec told her that the store has told two tons of apples (that would otherwise have been thrown away) since the experiment began a few weeks ago.

Stuart Rudick told me that Food Star Partners is also working with California farmers to collect fruits and vegetables that otherwise would be left in fields or thrown away.

“We want to prove the concept, start small and work out the kinks,” he said.

And so far?

“People like the product. The price points are fantastic,” he said. “And Andronico’s is very happy.” Clearly lots of work lies ahead, but this is a start.