Technologies Overview - Gasification

Gasification is a process that converts organic or fossil fuel based carbonaceous materials into carbon monoxide, hydrogen and carbon dioxide. This is achieved by reacting the material at high temperatures (>700 °C), without combustion, with a controlled amount of oxygen and/or steam.

Typically, advanced thermal treatment processes will treat prepared fuels (e.g. Refuse Derived Fuels) derived from municipal (or other) waste streams. This Refuse Derived Fuel (RDF) or Solid Recovered Fuel (SRF) comprises the energy-rich elements of the waste stream, typically paper, card and plastics.

Configuration

Waste streams accepted
Commercial and Industrial waste, certain fractions of Construction and Demolition waste, Refuse derived fuel (RDF)
Input capacity ranges
10k-100k tonnes per annum
Typical outputs
Electricity, heat and ash
Purposes
Recover energy from non-recyclable mixed waste streams
Indicative capital cost
R387,5m-R620m for a 60ktpa facility
Indicative operational cost
High
Life span
20-30 years
Skills requirements
High
Job creation opportunity
Low

Technology restrictions

  • Gasification systems is capital intensive.
  • All non-metal recyclable materials will be destroyed.
  • Fuel is bulky and frequent refueling is often required for continuous running of the system.

Main license requirements for gasification

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Advantages:

  • Captures carbon dioxide which is harmful to the environment
  • Provides energy security

Disadvantages:

  • Significant capital costs for these facilities
  • Requires highly skilled operators
  • Requires specific feedstock to gain the full potential
Case Study

Waste-fuelled gasification project, Greve in Chianti, Italy

Construction of the power station at Greve in Chianti in the early 1990s was funded bynthe municipalities in the area around Florence, Italy, to recover energy from MSW collected in the same area. In 1988, Termiska Processer AB (TPS) licensed their lowpressure, air-blown, circulating fluidized bed (CFB) gasification process to Ansaldo of Italy. TPS next provided the design of two refuse derived fuel (RDF) pellet gasifiers for a small commercial-scale plant at Loc. Testi, Passo dei Pecorai, Greve in Chianti, Italy. The plant was designed by Studio Ingenaria Ambientale and built by Ansaldo Aerimpianti, and was commissioned in 1992 and turned over to the owner, Servizi Ambientali Area Fiorentina (S.A.F.I.), early in 1993.In the late 1970s, TPS began development of CFB boilers, and in the mid 1980s turned their attention to CFB gasifiers. The impetus for this work was the high price of fuel oil and the desire in Scandinavia to utilize bark as a fuel in lime kilns. As a consequence, in 1984 TPS embarked on the development of a biomass-fuelled atmospheric pressure gasification system, and constructed a 2 MWt pilot plant gasifier. Although the technology developed by TPS was fairly sophisticated in that it was able to effectively andle a wide range of feedstock types, and was capable of being scaled up in size, the gas produced was heavily contaminated with tarry components that would make its use in gas turbines and engines difficult without gas cleaning. As a result, in 1988 a dolomite tar cracker, cold gas filter, wet scrubber and modified 500 kW diesel engine were developed and added to the pilot plant. As part of the Greve in Chianti project,test work was conducted in the pilot plant gasifier using Italian pelletized RDF as feedstock.

Source: : Natural Resources Canada/CANMET Energy Technology Centre (CETC), 2003.