A discussion of waste-to-energy (WTE) among waste management professionals can generate a lot of heat. Some professionals feel WTE should be the cornerstone of large, complex waste management systems. Others feel that WTE is environmentally destructive and toxic to humans, while advocates of recycling may fear that it preempts any hope of recycling a large portion of the waste stream.

There is a place for WTE within the field of waste management but its use is specific and not universal. For communities considering WTE, here are some guiding principles to keep in mind:

1. The U.S. Environmental Protection Agency's (EPA) solid waste hierarchy:

   1. Source reduction;

   2. Recycling or composting;

   3. Combusted with energy recovery; and

   4. Landfill or incineration without energy recovery.

2. Solid waste systems and services should be reliable.

3. Systems should be environmentally beneficial or benign.

4. The system's direct and indirect cost should be calculated over its life.

In communities that use WTE, recycling needs to happen first, and WTE can then process what cannot be reasonably and reliably recycled at a high and sustainable rate, meaning a recycling rate of at least 50 percent. WTE facilities should be sized to process the waste left over after recycling program goals are met and transform it into electricity. If steam sales and/or district energy customers are available, a co-generation plant should be included. Although our society is becoming smarter in generating less waste when making and delivering goods to consumers, historical waste generation rates show that our waste quantities continue to grow as our population increases.

In 2004, a survey of U.S. WTE facilities by the Integrated Waste Services Association, now the Washington-based Energy Recovery Council (www.energyrecoverycouncil.org) took a look at the effect WTE facilities have had on local recycling efforts. Data from EPA for the study year showed the overall municipal recycling rate in the United States to be 31 percent. By comparison, the 94 WTE communities contacted for this investigation had an average recycling rate of 34 percent. Ten years ago, WTE communities had an average recycling rate of 21 percent versus the national rate of 17 percent. Simply stated, there does not have to be a conflict; the two approaches can coexist and support an overall goal of minimizing what ends up in a landfill.

Of the 89 WTE facilities in the United States, 10 produce refuse-derived fuel. In these facilities, waste that has already been sorted for recyclables is processed again to recover additional recyclables. Using RDF in more electrical plants or industrial boilers is a way to increase the use of alternative fuels and increase recycling.

WTE and the Environment

According to EPA, 254 million tons of municipal solid waste were generated in 2007. This waste was managed in three ways: 33.4 percent was recycled, 12.6 percent went to WTE facilities, and the remaining 54 percent was landfilled. WTE facilities exported the equivalent of 2,300 megawatts of electricity to the power grid, while a few — such as those in Baltimore and Indianapolis — also distributed steam to downtown district energy loops. Their emissions meet or are below air pollution standards under the Clean Air Act (CAA), and they dispose of their ash products in regulated Subtitle D landfills safely without undue impact on the environment.

The environmental performance of these facilities speaks for itself. Today, WTE facilities have virtually no cumulative dioxin emissions, and they have achieved a 60-fold decrease in mercury emissions between 1987 and 2000, according to EPA. If you wonder how they are performing, take the time and review the environmental and safety performance of facilities such as those located in Alexandria, Va.; Baltimore; Modesto, Calif.; Miami; or Montgomery County, Md.

The regions of Durham and York in Ontario, Canada, (see www.durhamorkwaste.ca) found significant environmental benefits to WTE when comparing systems with a WTE facility located 75 miles away to one with a remote landfill located 300 miles away (assuming a 60 percent recycling level in both systems). An independent analysis found these alternatives to be economically comparable and noted that potential revenues from the sale of carbon credits and having a system less susceptible to inflationary transportation costs would make the WTE system even more economically attractive over the long term.

Fairfax, Va.-based Gershman, Brickner & Bratton (GBB) recently used the EPA's Waste Reduction Model (WARM) to compare the environmental benefits of systems with 50 percent recycling with different disposal components. The WARM modeling showed that a system with WTE compared to one either with mixed waste composting or landfilling as the primary disposal option was environmentally superior because of an additional 10 percent greenhouse gas reduction.

So, the question becomes, “If WTE facilities are environmentally beneficial and compatible with recycling, then why aren't more communities making them the centerpiece of their strategic vision?” The answer: money and siting.

WTE facilities cost a lot to build, and landfill disposal in the United States is relatively inexpensive even when the landfills are remotely located. GBB's recent analysis for systems with WTE bears this out. Disposal cost needs to approach $100 per ton before WTE becomes economically viable: the larger the WTE facility, the lower the WTE costs; the higher the price paid for electricity, the lower the cost; if cogeneration can be included, the lower the cost; if ash disposal can be cost-based versus market-price-based, this lowers the costs even further. Access to credit and financial markets for the capital cost is a major concern given the current economic climate.

Siting a WTE is a whole other issue, one best addressed in its own article.