Massachusetts Department of Environmental Protection moves away from gasification and pyrolysis consideration says the new report commissioned by the state.

A new study released today by the Tellus Institute commissioned by the Massachusetts Department of Environmental Protection found that "gasification and pyrolysis facilities are unlikely to play a major role in MSW management in Massachusetts by 2020."  The study can be downloaded at http://www.mass.gov/dep/recycle/priorities/dswmpu01.htm.   The study says that:

"Key issues informing this conclusion include: the lack of experience in the U.S. with large-scale alternative technology facilities successfully processing mixed MSW and generating energy; the long lead times to plan, site, construct, and permit such facilities; the significant capital costs required and the loss of solid waste management flexibility that is associated with the long-term contractual arrangements that such capital-intensive facilities require; and the relatively small benefit with respect to greenhouse gas emissions compared to diversion or landfilling."

The conclusions presented in the study are the following: 

1) From a lifecycle environmental emissions and energy perspective, source reduction, recycling and composting are the most advantageous management options for all (recyclable/compostable) materials in the waste stream. (See Tables ES-1 and ES-2, below.) This finding confirms the traditional solid waste management hierarchy that has guided MA DEP’s Solid Waste Master Plan to date.

2) After maximizing diversion through source reduction, recycling and composting, it is appropriate for DEP to continue to monitor developments regarding alternative waste management technologies that produce energy – gasification, pyrolysis, and anaerobic digestion. In evaluating conventional and alternative management options for the remaining waste stream, the competing needs of energy generation and prevention of climate change come into play, given that materials with high fossil fuel energy content, such as plastics and rubber, also emit high levels of greenhouse gases when they are combusted or processed for energy. Expected federal regulation of carbon emissions, or market mechanisms such as cap-and-trade systems, may place additional focus on solid waste management facilities as emission sources, making greenhouse gases an increasingly important consideration in future waste management decision-making.

3) Several factors lead us to conclude that gasification and pyrolysis facilities are unlikely to play a major role in MSW management in Massachusetts by 2020. Key issues informing this conclusion include: the lack of experience in the U.S. with large-scale alternative technology facilities successfully processing mixed MSW and generating energy; the long lead times to plan, site, construct, and permit such facilities; the significant capital costs required and the loss of solid waste management flexibility that is associated with the long-term contractual arrangements that such capital-intensive facilities require; and the relatively small benefit with respect to greenhouse gas emissions compared to diversion or landfilling.

4) The prospects for anaerobic digestion facilities appear to be more favorable given the extensive experience with such facilities in the U.S. for the processing of sewage sludge and farm waste and the fact that no significant human health or environmental impacts have been cited in the literature. Moreover, since anaerobic digestion is more similar to composting than high-temperate combustion, its risks are expected to be akin to composting, which is considered low-risk. Anaerobic digestion may be most suitable for source-separated organic material as an alternative to conventional composting. Ultimately, the degree to which anaerobic digestion makes sense will depend largely on the economics of such facilities, including the energy they produce, versus directly composting such material in aerobic composting facilities.

5) As summarized in Table ES-1, below, among the other technology options – landfilling, waste-to-energy incineration, and gasification/pyrolysis – from a life-cycle perspective no technology performs better than the others across all the seven emissions categories reviewed. However, reported per ton emission factors for gasification/pyrolysis facilities are lower than for WTE incineration facilities for all pollutants, and lower than landfill emissions for all except carbon dioxide (eCO₂). (Key assumptions and a discussion of the modeling results are presented in section III.)

6) For modern landfills, waste-to energy incinerators, as well as the gasification and pyrolysis plants, the emission factors used to compare environmental performance are based largely on modeling and/or vendor claims for modern, state-of-the art facilities, as opposed to actual operational data from real world experience. For example, actual operating performance for Massachusetts WTE facilities has been shown to produce far higher emissions than the modeled figures. Similarly, there remains significant uncertainty as to whether commercial scale gasification/ pyrolysis facilities processing MSW and generating energy can perform as well as the vendor claims or modeled emissions.

7) Preference among the alternative technology options based on environmental performance is dependent on the relative importance placed on eCO₂ emissions versus the other pollutants. For example, on a per ton MSW basis, modern landfills with efficient gas capture systems reduce two and a half times as much eCO₂ as gasification and pyrolysis facilities, and three and a half times as much as waste-to-energy incinerators.

8) From a life-cycle net energy perspective, waste diversion through recycling provides the most benefit, saving an estimated 2,250 kWh per ton of solid waste. Of the other waste management technologies, gasification and pyrolysis facilities have the most potential for energy production at about 660 kWh per ton, followed by modern waste to energy incinerators at 585 kWh per ton, and then anaerobic digestion, and landfilling. The estimated energy potential of the various management methods is summarized in Table ES-2, below.

Table ES-2: Net Energy Generation Potential Per Ton MSW

* Per-ton energy generation potential estimates are dependent on a number of factors including: the composition of the MSW stream, the specific technologies considered (e.g., fluid bed versus fixed bed for gasification), and the source of the data. Source references are provided in section III.

13) For both pollutant and energy impacts, the scenario analysis points to the significant benefits of broadening and strengthening the Commonwealth’s recycling and composting diversion programs and the modest additional benefits associated with shifting non-C&D MSW from landfills to new thermal processing facilities.