City Plans Biogas Renewable Energy Project

The City of Wilmington, DE, is planning a $35 million renewable energy project that will feature a facility that converts two sources of biogas into power and heat for the city's wastewater treatment plant.

Oct 1st, 2012

The City of Wilmington, DE, is planning a $35 million renewable energy project that will feature a facility that converts two sources of biogas into power and heat for the city's wastewater treatment plant.

The project is part of a city-wide initiative to decrease energy costs and greenhouse gas emissions, a program that has also included solar installations and energy-efficient building improvements. Combined, the upgrades will help the city trim its carbon footprint by approximately 35 percent and meet nearly 50 percent of its electricity needs with renewable energy.

The city will partner with Honeywell on the project. City officials intend to use the subsequent reduction in utility and operating costs, savings that are guaranteed through performance contracts with Honeywell, to fund the upgrades and ongoing support. In addition, the work is expected to deliver savings beyond the money required to finance the activities.

"The City of Wilmington continues to position itself as a leader in municipal sustainability," said Mayor James M. Baker. "By working with Honeywell to build the renewable energy facility and make a variety of other unique, innovative improvements across the city, we can significantly reduce energy consumption and greenhouse gases without extra funding from taxpayers."

The centerpiece of the new project is the construction of a Renewable Energy Biosolids Facility to harvest and harness biogas, supplying a renewable resource to not only generate electricity for the Hay Road Wastewater Treatment Plant, but provide thermal drying to greatly reduce the volume of sewage sludge the city pays to remove.

The biosolids facility will capture methane produced by anaerobic digesters at the Hay Road plant, a potential energy source that is currently flared off. The gas will mix with additional methane from the nearby Cherry Island Landfill, which is operated by the Delaware Solid Waste Authority.

The blend will be purified at the facility and used to power reciprocating engines that can generate up to 4 megawatts of electricity, enough energy to provide up to 90 percent of the treatment plant's power.

The biosolids that come out of the digesters will also be dehydrated by heat recovered from the engines. This thermal drying process is expected to reduce the amount of sludge the city needs to truck away by approximately 75 percent — from 140 to 35 tons per day — greatly reducing material-handling costs.

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