Energy-from-waste firm Covanta Energy's total greenhouse gas emissions fell around 33 percent from 2010 to 2011, according to the company's latest sustainability report.
Year-on-year the company reduced its absolute greenhouse gas emissions from 11.8 million to 7.9 million tons of CO2 equivalent. All but 51,000 tons of those emissions were direct emissions from Covanta's facilities.
The company has a broad goal of reducing overall emissions associated with its facilities, specifically with regard to dioxin and mercury. Covanta's trends for both mercury and dioxin demonstrate a year-on-year improvement, where the majority of results "are in the low end of the range," the report says. By 2011, more than 94 percent of Covanta's monitoring results showed dioxin emissions of less than a third of the EPA's regulatory limit. Also by 2011, more than 95 percent of Covanta's monitoring results showed mercury emissions of less than a fifth of the EPA's regulatory limit.
As a provider of energy-from-waste, Covanta's basic operations are carbon negative, the company says. The decrease in absolute emissions was accompanied by a 29 percent increase in the emissions the company is responsible for removing from the atmosphere.
In 2010, Covanta's net greenhouse gas footprint from operations was -13.4 million tons of CO2 equivalent. This metric improved to -17.3 million tons of CO2 equivalent in 2011.
The company's operations in 2011 avoided 18.1 million metric tons of CO2e from being emitted, by diverting waste from landfill. This was up from 17.9 million metric tons in 2010 and 16.8 million metric tons in 2009.
Based on estimates using the EPA’s Decision Support Tool, Covanta says about one ton of CO2-equivalent is reduced relative to landfilling for every ton of waste processed at an energy-from-waste facility. In addition, each ton of waste processed for energy eliminates the need to consume about one barrel of oil or one-quarter ton of coal at a fossil fuel-fired facility, the report says.
Water is essential for Covanta's waste-to-energy processes. At Covanta plants, water passes around the energy-from-waste heat exchange equipment and turns to steam, which, in turn, drives a turbine to generate electricity.
Covanta has a broad and ongoing goal of introducing initiatives that reduce overall water use at its plants and allow the use of lower-quality water. The report does not include specific figures for overall water use but it does include a case study from one plant.
Covanta's Indianapolis facility processes 2,175 tons of municipal solid waste per day, producing steam to power the downtown heating loop that services nearly all downtown businesses, Indiana University, Purdue University's Indianapolis campus, and Eli Lilly, the area's largest pharmaceutical manufacturer, the report says.
Over the past five years, Covanta Indianapolis has implemented several water savings projects to reduce both the amount of potable water consumed, and wastewater generated, by its operating processes. For example, a reverse osmosis process is saving about 44 million gallons of potable water per year. A supplemental concentrate reverse osmosis recovery system reduces the amount of wastewater generated by 60 percent, or 12 million gallons per year, the report says.
The company also recovers metals from the municipal solid waste it processes. Covanta increased the total tons of metals recycled from 390,000 tons in 2010 to 430,000 tons recycled in 2011, according to the report. About 4 percent of this amount comprised high-value nonferrous metals such as aluminum, brass, and copper.
Covanta says that the increase in recovery was due to an increase in the number and quality of systems separating metals at the company's plants. Covanta plans to improve existing systems and to install additional new metal projects in 2013 and 2014.
In November, news surfaced of Covanta and Schnitzer Steel teaming up to recycle steel from fishing nets and other unusable heavy equipment.
In October 2011, the company's UK arm dropped plans to build a waste-to-energy facility in Wales. Covanta blamed the move on local authorities’ “fragmented approach” to dealing with waste.
