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Our Campaign’s Rationale Not To Support Plasma Arc

posted Apr 20, 2011, 7:11 AM by Bob Wenzlau   [ updated Apr 25, 2011, 8:51 PM ]
Our campaign has focused on biologically-based strategies for the organic waste streams.  However, in several public forums and in online posts our campaign is challenged to embrace Plasma Arc.  

First and foremost, this is a moot discussion as the Initiative will not specify the technology other than representing a environmental improvement over existing methods. However, our campaign has been committed to biological methods - and in particular anaerobic processes, and not methods like Plasma Arc.

The proponents of Plasma Arc are strong in their belief, and it seemed reasonable to develop why our campaign will not be supporting Plasma Arc.

Let’s first start out with what is Plasma Arc?

Plasma arc gasification is a waste treatment technology that uses electrical energy and the high temperatures created by an electric arc gasifier. This arc breaks down waste primarily into elemental gas and solid waste (slag), in a device called a plasma converter. The process has been intended to be a net generator of electricity, depending upon the composition of input wastes, and to reduce the volumes of waste being sent to landfill sites. (Wikipedia)

Our campaign has many voices. We are fortunate to have assembled a Technology Committee, and the following represents our collected objections to this technology in Palo Alto and applied to our organic residues.
  • Plasma Arc Would Be Inefficient on Palo Alto’s Feedstocks.  The  Compost Blue Ribbon Task Force heard presentations during the course of its research that Plasma Arc works best on dry feedstocks.  We even observed considerable pre-processing to dry materials for introduction to the plasma arc. That our “feedstock” is very moist caused the Task Force not to pursue plasma arc technology.  Two principal feedstocks in Palo Alto are biosolids and foodwaste, and each are approximately 70 percent moisture. Peat International, a Plasma Arc vendor reports that feedstocks at 30 percent as requiring considerably more electrical energy to destroy.  
  • Plasma Arc is Difficult to Permit. No commercial plasma arc gasification facilities exist in the United States. The air permitting requirements for plasma arc are un-tested, and therefore pose a risk.  Many environmental organizations site in opposition to plasma arc, and one could anticipate their opposition during permit hearings. In contrast,  currently the State of California is establishing a special permit for anaerobic digestion technologies to expedite the State approval process for new anaerobic digestion facilities.
  • Plasma Arc Produces More Greenhouse Gases than Anaerobic Digestion. All the carbon that processed in a Plasma Arc is converted to carbon dioxide, where in an anaerobic digestion process a considerable amount of the carbon stays as a sequestered woody material.  An incentive of plasma arc seems to be the generation of inert slag, the slag volume is insignificant to the original waste.  
  • Precautionary Principle. The precautionary principle invites that if an action or policy has a suspected risk of causing harm to the public or to the environment, in the absence of scientific consensus that the action or policy is harmful, the burden of proof that it is not harmful falls on those taking the action.
Plasma arc can reasonably be suspected of posing a risk of harm from emissions, and a choice to move forward seemingly conflicts with the precautionary principal's tenets. The identified emissions from staged incinerators (inclusive of plasma arc) include particulate matter, volatile organic compounds (VOCs), heavy metals, dioxins, sulfur dioxide, carbon monoxide, mercury, carbon dioxide and furans. Even small amounts of some of these toxins can be harmful to human health and the environment. Mercury, for example, is a powerful and widespread neurotoxin that impairs motor, sensory and cognitive functions. Dioxin is the most potent carcinogen known to humankind—to which there is no known safe level of exposure. Health impacts of dioxin include cancer, disrupted sexual development, birth defects, immune system damage, behavioral disorders and altered sex ratios.
  • Plasma Arc is Incineration and Our  Community Consensus is to Move Away From Incineration.  Multiple definitions from the USEPA as well as the  European Union include plasma arc as a form of incineration.  For example  U.S. EPA Hazardous Waste Regulations (40 CFR 260.10) states that “Incinerator” means any enclosed device that: (1) Uses controlled flame combustion and neither meets the criteria for classification as a boiler, sludge dryer, or carbon regeneration unit, nor is listed as an industrial furnace; or (2) meets the definition of infrared incinerator or plasma arc incinerator. There is strong agreement within our campaign to shut down the current incinerator, and plasma arc as a form of incineration, and would conflict with the campaign’s tenants.
  • Plasma Arc Does Not Generate Compost.  Our campaign began with a desire to retain local compost production.  While the approach has evolved to incorporate anaerobic digestion, the process still generates the desired output: a finished compost.  Plasma arc generates slag - definitely not the sought compost.

Advocates for plasma arc will assert that the footprint of the technology is small, and thereby might make the Initiative's request for land not be pertinent.  Our campaign would maintain that the extra land is reasonable to avoid use of an incineration technology. Furthermore, advocates of plasma arc will claim this is not “incineration” as the first state of the process is low oxygen and an “arc” is used rather than a flame.  The campaign believes that government agencies adequately vetted this issue, and that plasma arc is by definition a form of incineration. Advocates will also speak to the lower cost of plasma arc.  Plasma arc works optimally with dry feedstocks, and as moisture increases the energy inputs to dry the feedstocks are needed.  Ultimately, the costs of plasma arc are not clear, and given other considerations warrant no further consideration by our campaign.