Energy Efficiency
The EnergyWorks initiative, supported by a $25 million grant from the U.S. Department of Energy's Better Buildings program, provides, free energy audits and very low interest loans (under 1%) for energy retrofits. The city also hired an Energy Manager to focus on policy and an Energy Conservation Coordinator to promote awareness of energy conservation among city employees. Funds from the Recovery Act also contributed to efficiency upgrades and including an energy management system for the city. Legislation passed which requires all new construction to meet or exceed Energy Star cool roof standards.
Harvesting Energy from Wastewater
Water Department Commissioner Neukrug sees wastewater plants more as resource recovery facilities these days. Water pumping, wastewater treatment and storm water management combined account for 40% of the municipal government's energy use.
The Northeast Wastewater Treatment Plant, which processes 190 million gallons of wastewater daily, is receiving de-icing fluid from Philadelphia's International Airport across the street and adds it to anaerobic digesters to boost methane production. "The airport saves roughly $100,000 a year, and we make $100,000 a year," he says.
Another waste-to-energy strategy they're looking at is adding co-digestion of food waste to boost methane production at the wastewater plant. They can also make biodiesel from sludge and scum. They plan to install a 5.6 megawatt (MW) cogeneration plant that will supply 86-100% of the energy demand. The wastewater plant will become a net producer of energy over the next 20 years, he says.
The Water Department is also working on a demonstration project to use sewer geothermal technologies to heat and cool one of its 20,000 square-foot compressor buildings. "In China for the Olympics it was used to heat and cool the Beijing train station," says Crockett of the Water Dept.
"The concept is very similar to ground geothermal, because the fluid in sewers is typically a constant temperature as is the ground and thus can be used as a heat source or sink for heating and cooling a building from a thermodynamic perspective." The only issue hindering widespread use of sewer geothermal is the separation of the material in sewage that could foul and impact the heating/cooling pump system, he explains, adding that recent improvements in the reliability and performance of those separation technologies are making it more appealing.
Other water treatment plants are using solar panels. "After we finish getting the Northeast cogen and southeast solar projects off the ground, we will be turning our attention to taking the land on top of our finished water storage at the Baxter Water Treatment Plant and using it to lease space for a 2 to 5 MW solar farm."
If built, this system would be able to provide enough energy to treat and deliver half the city's drinking water during a sunny day. "That project would take us one step closer to being able to deliver a 'glass of sunshine' to our customers," he notes. "In fact, we call that our "Glass of Sunshine" initiative."
Learn more about Philadelphia's Greenworks plan and it's Green Infrastructure.
Read the full article, published in Biocycle, a SustainableBusiness.com Content Partner.
