The following information was collected by Alan Muller, a consultant to NAB from Green Delaware. Alan is a long-time member of the international “GAIA” network (Global Alliance for Incinerator Alternatives). He has been the executive director of Green Delaware since 1995 and has been involved in successful campaigns in Delaware to effectively outlaw new incinerators. Alan is a former consultant to DuPont, involved in designing and marketing burners, so he has been on both sides of the issue.
According to Alan, basically, "gasification" is a major rebranding campaign of the burner people, more than anything technically new.
Here's some background you might find interesting:
Manufactured coal gas (sometimes referred to as "town gas"), and its several variants, was used for lighting throughout most of the nineteenth century. Consumers also used this gas as a fuel for heating and cooking from the late nineteenth through the mid-twentieth century in many locations where natural gas was unavailable. Generally, a rather simple process of heating coal, or other organic substance, produces a flammable gas. The resulting gas (a combination of carbon monoxide, hydrogen and other gasses depending upon the exact process) was stored in a "holder" or "gasometer" for later distribution. Coal based "gas works" produced manufactured gas from the early nineteenth century through the mid-twentieth century. Commercial utilization of manufactured coal gas occurred prior to that of natural gas due to the comparative ease of producing coal gas. The first manufactured coal gas light demonstration in the United States apparently took place in 1802.
By 1850, about 50 urban areas in the United States had a manufactured gas works. Generally, gas lighting was available only in medium sized or larger cities, and it was used for lighting streets, commercial establishments, and some residences." http://eh.net/encyclopedia/article/castaneda.gas.industry.us
And this is the environmental legacy http://www.hatheway.net/history.htm:
Manufactured gas must not be confused with natural gas, our great modern-day fuel source. Manufactured (or artificial) gas was made primarily from coal, as well as many other organic feedstocks ("biomass"). During the gas manufacture, tars were created and leaked, spilled or discharged to the environment. These tars are not susceptible to natural degradation and therefore have lives that will extend into geologic time. Manufactured gas plant wastes do not "go away."
The tars are made up of 500 to 3000 different compounds, typically toxic to humans, mammals, and plant life. Sometimes carcinogenic, these tars are more dense than water, thus tending to sink into the groundwater environment where they contaminate passing ground water. Tar is not to be considered equivalent to asphalt, which is a residual of natural petroleum deposits and of oil refineries. Also associated with gas manufacturing were captured impurities such as ammonia, cyanide, sulfur and heavy metals, particularly arsenic.
With Hatheway's estimated 52,000 or more former manufactured gas plants in the United States, the environmental impact becomes obvious. This website is dedicated to informing the public, elected and appointed officials, the media, educators and students about the little known history of manufactured gas and how its wastes impact our environment today.
More bad news about this is at http://www.epa.gov/reg3hscd/bfs/regional/industry/manufactured.htm
(There are major polluted gas plant sites in Delaware. Like most such sites, they aren't really getting cleaned up...)
On, one level, promoters claiming that they have a magic machine that can eat almost anything and turn it into "natural gas" with "no pollution" are just blowing smoke, so to speak.
On the other, there is just enough of a kernel of truth in gasification claims that good-faith investors get drawn in, government agencies give money, and so on.
Here's some background on this aspect:
To understand it, I think it helps to realize that all burning is gasification, in the sense that solids and liquids generally don't burn. Any solid or liquid needs to be evaporated or broken down into gaseous material before it can burn. Look closely at a bonfire or a candle flame or whatever and you can see what is happening: the head of the flame first melts the wax, then vaporizes it, and the vapor burns (http://www.scienceiq.com/ShowFact.cfm?ID=67).
Here's a comment on wood burning, in the context of firefighting:
http://www.madsci.org/posts/archives/mar2000/953740466.Ch.r.html
You are correct, wood rapidly oxidizes, but does not burn. As the wood is
heated to its flashpoint and further ont to its burning point, it produces
a gas. It is this gas which burns and reduces the wood to ashes. The point
where the gas is created is called the interface of the fire and you will
will notice if you look very closely that fire does not actually touch an
indvidual peice of wood but there is a very small space between the slame
and the piece offf wood. This is where the oxidation-reduction chemical
reaction takes place which allows the fire to sustain itself at approximately 900
degress farenheit. For more information see the International Fire
service's 4th Edition of "Essentials of Firefighting.'' Donald E. Duggan
Here's another in the context of lighting a wood fire: http://www.woodheat.org/tips/technique.htm
So, in a typical burner situation, the "gasification" and the "combustion" take place close to each other and we don't think much about how it is a multi-stage process.
We can, if we want, heat ("gasify") the fuel in one chamber and burn it somewhere else, and there can be engineering advantages to this, but it doesn't change anything fundamental. What goes in has to come out somewhere ... combustion byproducts include all sorts of harmful substances.
As for SilvaGas:
I've run into them before but took another look at their site. Mostly hype.
They claim, for example, that their syngas is "INTERCHANGEABLE WITH NATURAL GAS AND FUEL OIL," and "Our product gas can be used in conventional equipment designed for natural gas or fuel oil without modifications." But they also say: "The SilvaGas process produces a medium-Btu gas (450-500 Btu/scf)"
But natural gas has about 1000 Btu/scf [standard cubic foot], twice what they claim. So, their product is obviously NOT interchangeable with natural gas and could not be fed into the Nat gas distribution system...
This is typical of the misrepresentations used by the burner people...
As for “plasma arc” technology, this refers to a process whereby an electric arc (think of welding or an old-fashioned arc lamp) is used to heat wastes to very high temperatures. Theoretically, the temperatures can be great enough to break wastes down into their basic constituent molecules. So this process can be considered a form of "gasification." However, the amounts of electricity needed to create and maintain the arc are large, usually more than could be generated by burning gases created by the arc. In spite of plenty of extravagant claims by promoters, this technology has no potential for power generation and has no commercial track record—and probably no potential to build one—in waste incineration.
The following information about gasification is an article from the Solid Waste & Recycling Magazine on-line from Canada. The citation is:
http://www.solidwastemag.com/issues/ISarticle.asp?id=186245&story_id=188...
Gasification: Waste management lessons from Los Angeles
By: John Nicholson, M.Sc., P.Eng., who is a consultant based in Toronto, Ontario. Contact John at jnicholsonjr@rogers.com
When the City of Los Angeles, California, began a search of treatment technologies to manage its non-recycled municipal solid waste, it had the laudable objective of identifying alternative waste processing technologies that would increase landfill diversion in an environmentally sound manner, while emphasizing options that are energy efficient, socially acceptable and economical.
It began its in-depth evaluation by looking at 225 waste technologies suppliers offering thermal, biological/chemical, or physical treatment. Only 26 suppliers were able to demonstrate that their systems met the city's screening criteria. To pass the technical screening, each supplier had to demonstrate their technology: has a processing capacity of 200 tons per day (tpd); is in commercial operation or is commercial-ready; produces marketable byproducts; and, is compatible with post-source separated residential waste.
An RFQ was sent to 26 suppliers that met the initial technology screening criteria, of which 17 responded. In order to get short listed, each supplier had to meet further criteria used to rate the performance of each technology. These included waste treatability, conversion performance, throughput requirement, commercial status, and technology capability. The evaluation also included several site visits.
At the conclusion of its process, the city was left with five technology suppliers that were able to pass its two levels of screening. Interestingly, all were thermal treatment —only one being mass burn waste-to-energy and others that were pyrolysis/gasification. The city subsequently issued an RFP mid-February.
Overall winner:
The highest score in the City of L.A.'s evaluation went to Thermoselect technology. Thermoselect is a Swiss company that licenses its technology Interstate Waste Technologies in the United States. In Canada the technology is licensed by Quebec- based 3R Synergy Inc. (Contact Georges Vezina at gvezina@bellnet.ca)
Thermoselect's technology is a high-temperature gasification process that transforms waste into useful materials. Gasification of organic waste residue using pure oxygen takes place at a processing temperature of up to 2,000° C, melting down all inorganic residue waste (glass, ceramics, metal).
The process produces a mixed granulate; the mineral part can be used as a concrete aggregate in construction, for sand blasting or as a raw material in the cement industry. The metallic granulate is almost entirely composed of elemental iron and can be put to metallurgical uses. The result is 99 per cent diversion of incoming waste from landfill.
Thermoselect's oldest commercial plant has been in operation since 1999 in Chiba, Japan processing 104,000 tonnes per year (300 tonnes per day) of industrial waste, sludge, and municipal solid waste. There are six other commercial facilities in Asia ranging in processing capacity from 95 to 555 tonnes per day.
The winner's warts:
In an April 2006, Greenaction for Health and Environmental Justice, and Global Alliance for Incinerator Alternatives (two anti-incineration non-governmental groups) released a report raising serious allegations about the safety and reliability of advanced thermal technologies in the treatment of waste. The report Incinerators in Disguise: Case Studies of Gasification, Pyrolysis, and Plasma in Europe, Asia, and the United States, included a case study on a Thermoselect facility in Karlsruhe, Germany.
The Incinerators in Disguise report claims that Thermoselect's Karlsruhe facility in Germany was forced to close in 2004 due to recurring operational problems. The report makes a number of claims including a statement that the company lost $400 million Euros (over CDN $500 million) in the venture.
Thermoselect contends that the information in the Greenaction/Global Alliance document "is partly not true, partly outdated, partly not complete." Even though it was published in 2006, it refers to information that occurred five to eight years ago. Thermoselect correctly points out that the report fails to mention the successful operation of seven Thermoselect full-scale commercial facilities.
Criticism and conclusions:
At a recent presentation given at the Association of Municipal Recycling Coordinators (AMRC), the following viewpoint was offered on gasification technologies: Almost no full-scale gasification plants currently operating; proponent companies are promoting either technical ideas or extrapolating from very small facilities to the large-scale plants that they are proposing to build; and, the promise of gasification has not been matched by the reality of the operations of the technology.
The statements given at the AMRC conference appear to contradict the reality of seven full-scale Thermoselect facilities. A more balanced view on advanced thermal technologies is given in the City of Los Angeles Summary report that states, "Thermal conversion technologies have been in successful, long-term use around the world, although typically using more homogeneous feedstocks such as coal and biomass. While technical challenges are expected, because of their relatively short operating history using waste as a feedstock, these challenges are judged to be manageable."
Just as there are problems with recycling facilities and composting sites, thermal treatment facilities may experience problems, but they're improving all the time. One can cherry picks examples of unsuccessful waste management systems to "prove" a point, but for environmental professionals, it is critical to weigh all the evidence before reaching a conclusion.