July 1, 2009

The Growing Role of Waste-to-Energy in the U.S.

Angela Neville, JD

Using nonhazardous waste for power generation is a trend that’s gaining steam for several reasons. Though there are several environmental reasons, another is the reliability of the fuel supply.

"Fossil fuels will play a smaller role in our energy future. Renewable and indigenous fuels will become more prominent. Carbon management is here to stay," said Dr. Marco J. Castaldi, a professor in the Department of Earth and Environmental Engineering at Columbia University in New York City, citing the findings of the National Research Council of the National Academies.

This was just one of many forward-looking statements made during the presentations and discussions that occurred on May 11 at the preconference workshop on biomass fundamentals and applications, which was held in conjunction with ELECTRIC POWER. In particular, Castaldi’s presentation centered on trends related to U.S. power plants that use waste-to-energy (WTE) technology. He emphasized that WTE plants are poised to become an important part of the U.S. electric generation industry.

New Power Paradigm

Castaldi pointed out that the new paradigm emerging in U.S. energy policy has an emphasis on the following issues:

• The security of the procurement of fuel and growing concerns about supply chain disruptions.

• The projected increased energy demand.

• The rising concentration of atmospheric CO₂.

• Space-constrained or preferred land use.

"In the U.S., there is a strong need for carbon-neutral energy production," he said. "Zero emissions mean more than just sequestering CO ₂ from fossil fuels. We need to reduce our dependence on single feedstocks. We need to turn to indigenous and distributed sources of fuel. However, power produced from waste/biomass must be as economically attractive as current sources such as fossil fuels."

Castaldi’s presentation focused on the increased use of WTE facilities as a response to these issues. "WTE conserves fossil fuels by generating electricity," he said. "One ton of municipal solid waste (MSW) combusted equals 45 gallons of oil or 0.28 tons of coal. Currently, WTE facilities process 14% of all U.S. MSW."

One clear advantage of using nonhazardous MSW as a fuel source for American electric power generation is its sheer volume. More than 220 million tons of MSW are generated each year in the U.S., according to Castaldi. U.S. landfills are filling up, and MSW disposal costs are steadily increasing. Another benefit of using MSW as a fuel source for generating electricity is that it emits two-thirds less CO₂ than coal when combusted.

"Currently, two modern ways to dispose of post-recycling solid waste exist," Castaldi said. "First, there is thermal treatment with energy recovery. The heat content per MSW metric ton can generate more than 2,800 kWh of electricity. The second way is through controlled landfilling with partial methane recovery. The heat content in the methane generated from an MSW metric ton can generate more than 760 kWh of electricity."

The use of WTE is experiencing strong international growth (Figure 1). Castaldi cited the following statistics:

• Thirty-five nations are currently using WTE technology.

• More than 600 WTE plants are in operation.

• The global WTE industry processes approximately 170 million metric tons of waste per year.

• In the U.S., the WTE industry processes more than 26 million metric tons of waste per year.

• Globally, urban landfilling manages approximately 830 million metric tons of waste per year.

• In comparison, U.S. landfills handle around 225 million metric tons of waste per year.