Portlanders may be speaking a lot about Poop to Power this summer, when the city treatment plant expects to begin converting sewage into renewable natural gas.

But eggshells, chicken bones and rotting produce won't be part of the mix, now that Metro has scrapped talks with Waste Management Inc. to collect the region's food scraps and turn it into energy at the same city plant. In December, Metro ended nearly a year's negotiations with Waste Management — which was partnering with the city Bureau of Environmental Services — after failing to reach agreement on the price and volume of food scraps to be processed at the bureau's Columbia Boulevard Wastewater Treatment Plant in North Portland.