Electrical production via gasification of abundant carbonaceous feed-stocks such as coal, lignite, petroleum coke, wood waste, plastics, MSW (municipal solid waste) is the easiest use of a gasifier. The reason for this fact is that modern turbine generators are available that are capable of running on relatively low BTU and relatively dirty gas. This requirement makes the gasification equipment much less capital intensive, as will be explained below.
Gasification is an oxygen deficient combustion process. Rather than producing flame, carbon dioxide (CO2) and water (H2O) as combustion does, the primary output of gasification is carbon monoxide (CO) and hydrogen (H2). This gas produced from gasification is known as synthesis gas, or syngas. The purity of the syngas is of primary concern to the technology, and how it is produced and the expense of the equipment to do so depends in large part on its end use. In cases where high purities of syngas are required, oxygen enriched air, steam, or a combination thereof is input into the gasification chamber. This requirement adds expense to the system. High purity syngas is required, for instance, for the production of liquid fuels from the syngas. Electricity produced from syngas does not require as high purity syngas, i.e. it can be a more dilute form that includes nitrogen. Gasifiers that inlet unprocessed air are known as air-blown, and are generally the least expensive ones.
Depending on the type of gasifier the produced syngas will contain tars, liquids and other impurities. Many gasification systems include syngas cleanup technologies for removing these impurities. This is an important facet of the technology for electrical production.
Turbine generator sets (gen-sets) capable of running on gasifier synthesis gas are now readily available from a number of manufacturers. These gen-sets are quite robust with regard to the amount of syngas impurity they can tolerate. They are also quite modular, allowing for quite a lot of flexibility in their application.
Energy Quest Inc. has access through license to a very innovative, modular, air blown gasifier technology for producing electrical power. This gasifier employs what is known as fluidized bed gasification (FBG) scheme. A fluidized bed gasifier employs a substance such as sand to dramatically increase the efficiency of the gasification process. Energy Quest’s technology employs a number of intellectual property advances over competitive systems. And very importantly for this application it has been designed in a modular way so that it can be deployed on a relatively small scale. This modularity gives it great flexibility when it comes to power generation in that it can be sized according to the need of a particular application, for example 5MW, 10 MW and larger. Below is an illustration of a trailer mounted unit:
It is also a relatively simple system so its capital and operating costs are lower than competitive systems. Following is a picture of an Energy Quest FBG unit and a process flow diagram of the system: