Editing Gasification (section)

==Feedstock==
There are a large number of different feedstock types for use in a gasifier, each with different characteristics, including size, shape, bulk density, moisture content, energy content, chemical composition, ash fusion characteristics, and homogeneity of all these properties. Coal and petroleum coke are used as primary feedstocks for many large gasification plants worldwide. Additionally, a variety of biomass and waste-derived feedstocks can be gasified, with wood pellets and chips, waste wood, plastics and aluminium, [[Municipal Solid Waste]] (MSW), [[Refuse-derived fuel]] (RDF), agricultural and industrial wastes, sewage sludge, switch grass, discarded seed corn, corn stover and other crop residues all being used.<ref name="nnfcc"/>

[[Chemrec]] has developed a process for gasification of [[black liquor]].<ref name="chemrec"/>

===Waste disposal===
[[File:HTCW reactor.jpg|right|thumbnail|150px|HTCW reactor, one of several proposed waste gasification processes]]

Waste gasification has several advantages over incineration:
* The necessary extensive flue gas cleaning may be performed on the syngas instead of the much larger volume of [[flue gas]] after combustion.
* [[Electric power]] may be generated in [[internal combustion engine|engines]] and [[gas turbine]]s, which are much cheaper and more efficient than the [[Rankine cycle|steam cycle]] used in incineration. Even fuel cells may potentially be used, but these have rather severe requirements regarding the purity of the gas.
* Chemical processing ([[Gas to liquids]]) of the syngas may produce other synthetic fuels instead of electricity.
* Some gasification processes treat ash containing heavy metals at very high temperatures so that it is released in a glassy and chemically stable form.

A major challenge for waste gasification technologies is to reach an acceptable (positive) gross electric efficiency. The high efficiency of converting syngas to electric power is counteracted by significant power consumption in the waste preprocessing, the consumption of large amounts of pure oxygen (which is often used as gasification agent), and gas cleaning. Another challenge becoming apparent when implementing the processes in real life is to obtain long service intervals in the plants, so that it is not necessary to close down the plant every few months for cleaning the reactor.

Environmental advocates have called gasification "incineration in disguise" and argue that the technology is still dangerous to air quality and public health.  "Since 2003 numerous proposals for waste treatment facilities hoping to use... gasification technologies failed to receive final approval to operate when the claims of project proponents did not withstand public and governmental scrutiny of key claims," according to the Global Alliance for Incinerator Alternatives.<ref>{{Cite web |url=http://www.no-burn.org/downloads/Incinerators%20in%20Disguise:%20Case%20Studies%20of%20Gasification,%20Pyrolysis,%20and%20Plasma%20in%20Europe,%20Asia,%20and%20the%20United%20States%20.pdf |title=GAIA Report |access-date=2013-07-10 |archive-url=https://web.archive.org/web/20120503091440/http://www.no-burn.org/downloads/Incinerators%20in%20Disguise:%20Case%20Studies%20of%20Gasification,%20Pyrolysis,%20and%20Plasma%20in%20Europe,%20Asia,%20and%20the%20United%20States%20.pdf |archive-date=2012-05-03 |url-status=dead }}</ref> One facility which operated from 2009–2011 in Ottawa had 29 "emissions incidents" and 13 "spills" over those three years.  It was also only able to operate roughly 25% of the time.<ref>[http://www.zerowasteottawa.com/docs/141-RT-3557_RevA_PTR%20Final%20Assessment%20Report%20FINAL.pdf Plasco Energy Group Demonstration Project Final Report] {{webarchive|url=https://web.archive.org/web/20110718153256/http://www.zerowasteottawa.com/docs/141-RT-3557_RevA_PTR%20Final%20Assessment%20Report%20FINAL.pdf |date=2011-07-18 }}</ref>

Several waste gasification processes have been proposed, but few have yet been built and tested, and only a handful have been implemented as plants processing real waste, and most of the time in combination with fossil fuels.<ref>[http://www.environment-agency.gov.uk/wtd/679004/679021/679065/ Gasification case studies] {{webarchive|url=https://web.archive.org/web/20060804215602/http://www.environment-agency.gov.uk/wtd/679004/679021/679065/ |date=2006-08-04 }} by the [[Environment Agency]] of England and Wales</ref>

One plant (in [[Chiba, Chiba|Chiba]], Japan, using the Thermoselect process<ref>[http://www.thermoselect.com Thermoselect website] {{Webarchive|url=https://web.archive.org/web/20150506210441/http://www.thermoselect.com/ |date=2015-05-06 }} — A waste gasification plant supplier</ref>) has been processing industrial waste with natural gas and purified oxygen since year 2000, but has not yet documented positive net energy production from the process.

In 2007 [[Ze-gen]] erected a waste gasification demonstration facility in [[New Bedford, Massachusetts]]. The facility was designed to demonstrate gasification of specific non-MSW waste streams using ''liquid metal gasification''.<ref>{{Cite news
 |title        = Teaching the Government to Love Garbage
 |work         = [[GreenTech]]
 |date         = 2009-12-14
 |url          = http://news.cnet.com/greentech/?keyword=Ze-gen
 |access-date   = 2010-01-07
 |archive-url  = https://web.archive.org/web/20110617032954/http://news.cnet.com/greentech/?keyword=Ze-gen
 |archive-date = 2011-06-17
 |url-status     = live
}}</ref> This facility came after widespread public opposition shelved plans for a similar plant in [[Attleboro, Massachusetts]].<ref>{{cite web |url=http://www.thesunchronicle.com/news/news_updates/ze-gen-withdraws-plans-for-attleboro-gasification-plant/article_38e57ba7-249b-5d77-ad8b-9f247d127723.html |title=Ze-gen withdraws plans for Attleboro gasification plant |date=24 May 2011 |publisher=The Sun Chronicle}}</ref> Today Ze-gen appears to be defunct, and the company website was taken down in 2014.<ref>{{cite web|url=http://p3nlhclust404.shr.prod.phx3.secureserver.net/SharedContent/redirect_0.html|archive-url=https://web.archive.org/web/20140122172324/http://p3nlhclust404.shr.prod.phx3.secureserver.net/SharedContent/redirect_0.html|url-status=dead|archive-date=22 January 2014|title=Site Suspended - This site has stepped out for a bit|date=22 January 2014}}</ref>

Also in the US, in 2011 a plasma system delivered by PyroGenesis Canada Inc. was tested to gasify municipal solid waste, [[hazardous waste]] and biomedical waste at the Hurlburt Field Florida Special Operations Command Air Force base. The plant, which cost $7.4 million to construct,<ref>{{cite web|url=http://biomassmagazine.com/articles/5745/pyrogenesis-perfecting-plasma|title=Pyrogenesis Perfecting Plasma - Biomassmagazine.com|website=biomassmagazine.com|access-date=2018-03-07|archive-url=https://web.archive.org/web/20141023144228/http://biomassmagazine.com/articles/5745/pyrogenesis-perfecting-plasma|archive-date=2014-10-23|url-status=live}}</ref> was closed and sold at a government liquidation auction in May 2013.<ref>{{Cite web |url=http://www.govliquidation.com/auction/view?auctionId=6241220 |title=Archived copy |access-date=2018-03-07 |archive-url=https://web.archive.org/web/20180308103429/http://www.govliquidation.com/auction/view?auctionId=6241220 |archive-date=2018-03-08 |url-status=dead }}</ref><ref>{{cite web |url=http://www.rewmag.com/dod-gasification-auction-pyrogenesis.aspx |title=DoD to Auction off Gasification Equipment - Renewable Energy from Waste |access-date=2014-10-18 |url-status=dead |archive-url=https://web.archive.org/web/20141018222036/http://www.rewmag.com/dod-gasification-auction-pyrogenesis.aspx |archive-date=2014-10-18 }}</ref>  The opening bid was $25.  The winning bid was sealed.

In December 2022, the Sierra BioFuels Plant opened in Reno, Nevada, converting landfill waste to synthetic crude oil. <ref>{{Cite web |title=Sierra BioFuels Plant |url=https://www.fulcrum-bioenergy.com/sierra-biofuels |access-date=2023-12-15 |website=Fulcrum BioEnergy |language=en}}</ref>