Overview – Biomass Gasification
BIOS BIOENERGIESYSTEME GmbH, Graz
Biomass gasification is an alternative option of thermal biomass utilisation for the production of heat and power based on biomass. Within the last 20 years several different gasification technologies were developed and demonstration plants were realised. Based on the experience from these demonstration plants the gasification technologies were further developed. Thus, some gasification technologies are ready or close to hit the market.
Gasification plants consist of several process steps, which are shown in figure 1. The solid biomass fuel delivered needs to be adjusted (fuel conditioning and handling) to the fuel characteristics (particle size, water content) required for the gasification process. The conditioned fuel enters the gasification process, which produces raw product gas. The raw product gas needs to be cleaned in order to achieve the product gas quality needed for further utilisation. The cleaned product gas is used for the production of electric power, heat and fuel based on different technologies.
Explanations: The framed rectangles show the process steps while the arrows show the conversion stages of the fuel during the gasification. The framed rectangles below show the different technologic options for each process step.
During the thermo-chemical biomass gasification process solid biomass is cracked by thermal energy and a fumigator and converted into a product gas. The product gas is cleaned and used for the production of heat and power e.g. by gas engines (biomass CHP).
The main advantage of the biomass gasification technology is the high electric efficiency due to the power production with gas engines. Furthermore, alternative applications of the product gas such as production of fuel or feed-in into the public gas grid (methanisation of wood gas) is possible.
The high temperature waste heat of the gasification process and the gas engine are utilisable in an ORC unit in order to produce additional electric power and further increase the electric plant efficiency.
Low temperature waste heat is utilisable for space and process heat supply as well as for biomass fuel drying. An efficient heat utilisation is necessary in order to achieve high overall plant efficiencies.
You can find a detailed description of the production of heat and power based on biomass gasification under:
Electricity from Biomass – Biomass Gasification
Procedure for the selection and evaluation of biomass gasification technologies
The following procedure is recommended for the evaluation of the feasibility of biomass gasification technologies:
- Technological evaluation and comparison of different biomass gasification systems – important, since many systems are still under development and not ready to hit the market
- Economical evaluation of the gasification technologies compared to a reference system (e.g. biomass CHP plant based on combustion) – important, since a high electric efficiency does not necessarily mean a better economic performance (investment and operation costs have to be considered as well)
- Evaluation of already available reference plants for a particular gasification technology – important, in order to obtain information regarding reliability and availability
- Verification of the emissions (exhaust gas, waste water, ash) of gasification plants compared to expected emission limits and guiding values respectively – important since an ecological operation based on economically meaningful site constraints is required
- Overall evaluation of the systems based on the results of topics 1) to 4)
BIOS BIOENERGIESYSTEME GmbH performs this evaluation procedure based on appropriate expertise and in a neutral way.
Working field of the BIOS BIOENERGIESYSTEME GmbH
- Development, comparison as well as technical and economical evaluation of different biomass gasification technologies as a basis for the selection of an adequate technology
- Planning of thermal oil systems for the internal heat supply, heat recovery and power production based on the ORC process
- Feasibility studies
- Preliminary plant design
- Preparation of permit applications
- Detailed design, request for proposals (RFP)
- Supervision of plant construction and commissioning
- Plant monitoring, process and performance optimisation