Beyond
Waste-to-Energy


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In the 1980s, the waste processing industry did a play on words to demonstrate the beneficial electrical generation capabilities of their systems. The plants became known as waste-to-energy facilities, replacing the reference to waste incineration which for years had brought negative connotations and community angst.

While waste-to-energy (WTE) remains the accepted industry term to define the process by which usable electricity is created from the combustion of municipal solid waste, it does not adequately describe an advanced facility under consideration in Los Angeles. The next-generation facility, developed by Green Conversion Systems (GCS), Rye, NY, features advanced technologies for minimizing emissions and offers the capability to convert essentially all of the waste it receives into not only electrical power, but also recyclable byproducts.

“Waste conversion is the more suitable description for the new facility,” said Dominic Meo III of Meo & Associates, a consultancy based in Huntington Beach, CA, which is involved in efforts to site the plant. “GCS is offering a zero-waste facility, which is designed from the ground up to maximize the recovery of resources contained in the waste stream of the plant, after recyclables are removed.”

Advanced Technology

The GCS plant could offer municipalities the best approach to date for sustainable waste management and, in the process, enable the industry to garner legislative support and public approval of WTE. The system proposed in Los Angeles is based on the design of a waste conversion facility, called MVR, which has been in operation in Hamburg, Germany since 1999. At the heart of the new plant is the proprietary Advanced Thermal Recycling (ATR) technology providing high-level emissions control and materials recovery. To control nitrogen oxide (NOx) emissions, the facility combines non-catalytic and catalytic reduction to reduce the emissions on a par with a modern natural gas-fired power plant operating in southern California, according to the developers.

GCS’s process for treating ash. Image: GCS

The GCS design employs dual wet scrubbers to handle chlorine gas and sulfur oxides, converting the pollutants into high-grade commercial products. The chlorine is recovered in the first wet scrubber, which uses water to remove acid vapors. The weak acid is then sent to a separate plant within the facility to create commercial-grade hydrochloric acid.

In the second scrubber, sulfur oxides are recovered via a treatment process involving lime to form gypsum for use in wallboards and other building materials.

Treated bottom ash size fractions. Image: GCS

“Most waste-to-energy plants remove the chlorine and sulfur oxides together in one scrubber, creating a waste stream that has no commercial value,” said Meo. “The GCS facility will turn out high-quality products that can be sold in the commercial marketplace to bring in revenue to help offset the costs of operating the facility.”

The ash is also recycled. Unlike conventional WTE plants, which process fly ash and bottom ash together, GCS uses processes developed at the Hamburg facility to treat the ash types separately for optimum recovery and reuse. The bottom ash is processed to recover residual ferrous and non-ferrous metals and glass products, which are washed and screened to create a mixture of different minerals for use as an aggregate in the production of cement or asphalt, or as structural construction fill.

The fly ash is divided into boiler fly ash and filter fly ash. The former is recycled internally, and injected into the emission control system along with activated carbon.

In some applications, the boiler fly ash can be made into a “low-carbon” concrete. Diversified Minerals, Inc., Oxnard, CA, has been carrying out research on the novel concrete, which passes ASTM tests for compressive strength and also California’s rigorous standards for nonhazardous materials.

The filter fly ash is fed into an extraction system, where the ash is treated sequentially with ammonia and acid to remove metals that can be recycled in metal foundries. The non-soluble residue from the extraction process, along with the spent activated carbon, boiler fly ash, and fine particles that are washed out from the bottom ash are returned to the combustion system, providing additional thermal energy.

“ATR is pushing material recovery to the maximum,” said Meo. “The GCS approach meets municipal goals to divert waste from landfills, and is a proven option for cities and counties that have announced zero-waste programs.”

According to Meo, less than one percent of the waste fed into the GCS plant remains for disposal.

The Question of Public Acceptance

Although the developers are presenting the GCS system as a technology for sustainable waste management and player in the nation’s green economy, it remains to be seen if the facility will be embraced by a skeptical public, which for years has viewed waste-to-energy as smoke-belching, high-polluting garbage incineration and which considers WTE a disincentive to recycling. As speakers in the May 30 webinar in the ASME Energy Forum will say, the industry right now faces several challenges. The industry struggles to acquire permits and licenses for new plant construction; most activity in the last ten to 15 years has been focused on expanding already existing WTE facilities.

Still, Meo and his clients at Green Conversion Systems strongly believe the new facility can be an effective and environmentally sound waste management strategy for towns and municipalities across the nation, particularly those – like Los Angeles – that plan to divert waste from landfills. Meo realizes that a great deal of community outreach will be required to educate environmentalists and public officials.

“The facility proposed for Los Angeles marks an unprecedented step forward in waste management,” said Meo. “What we have here is a plant with very advanced materials recovery capabilities and high-performing emissions control systems, which produces reusable materials along with electrical power and recyclable byproducts.”

Register here for a free webinar on waste-to-energy technology.

The facility proposed for Los Angeles marks an unprecedented step forward in waste management.

Dominic Meo, Meo & Associates

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May 2013

by John Varrasi, ASME Public Information