Take, make, and dispose--for years that has been the developed world's economic model. This consumption cycle led the World Bank to estimate that the globe was on track to produce 6 million metric tons of solid waste per day by 2025, up from 3.5 million metric tons in 2010.

But there are signs the take-make-dispose paradigm is shifting, and some of the world's largest companies are helping to drive change through their scale.

At Fortune’s Brainstorm E conference in Carlsbad, Calif. on Monday, the chief sustainability officers of Ikea, Walmart , and Coca-Cola discussed what they're doing to improve their companies' and consumers’ environmental footprints. Here are some of the coolest ideas we heard:

Ikea: The furnishings giant has instituted a “save the furniture program” in Belgium. People bring in old furniture, are given a voucher, and Ikea then sells the furniture for the same price that is on that voucher. Chief sustainability officer Steve Howard says that the company will implement a U.S. pilot program next year, which won’t be just for Ikea furniture but an “amnesty for pre-loved furniture.” To encourage people to fix broken furniture rather than throw it away, the company is now shipping a million spare parts to repair products.

Ikea has made energy a big focus. The Swedish brand operates 29 wind farms and 800,000 solar panels, having invested 1.6 billion Euros into renewables. Ikea is "a renewable power company today,” Howard says. “We've taken power from a cost to profit center." The company is also driving consumer behavior by selling solar panels and exclusively LED light bulbs in its stores.

Walmart: As the biggest seller of groceries in the U.S., Walmart has taken a close look at inefficiencies within the food system. The company has changed “best by” or “sell by” dates on its products to “best used by” dates to make it clearer to consumers when food has gone bad, which cuts back on food waste, says Walmart chief sustainability officer Kathleen McLaughlin. The retailer now takes 25,000 tractor-trailer loads of food waste to anaerobic digesters, which saves it from going into landfills and instead converts the tossed food into biogas. The company is also working with suppliers to help farmers optimize fertilizer use through precision agriculture.

Coca-Cola: The beverage company is looking at technology that would let it reuse water in every aspect of production. Pilot programs have reduced water by 30%, says Coca-Cola chief sustainability officer Bea Perez. But she notes that the company can push the technology and dialogue, but still needs to follow the consumer, and is therefore grappling with the question of whether consumers would be willing to drink it. Coke has also done work around packaging, turning recycled bottles into luxury goods like scarves and bags. The big reach dream: to one day have a bottle that the consumer can eat.