ADVANCED POWER PLANT CONCEPT WITH APPLICATION OF EXHAUST CO2 TO LIQUID FUEL PRODUCTION

Today there is a growing concern about the ramifications of global warming resulting from the use of fossil fuels and the associated carbon dioxide emissions. Oxy-fuel combustion is a promising response to this issue, since the product of the combustion is a CO2 rich flue gas, which requires no further separation from other emission gases and thus can be sequestrated, or utilized.

Here we present an analysis of a novel technology for combining oxy-fuel combustion with utilization of the CO2 rich flue gas for syntetic fuel production. The technology concept involves a new method of using concentrated solar energy for the dissociation of carbon dioxide (CO2) to carbon monoxide (CO) and oxygen (O-2). Simultaneously, the same device can dissociate water (H2O) to hydrogen (H-2) and oxygen (O-2). The CO, or the mixture of CO and H-2 (called Syngas), can then be used as a gaseous fuel (e.g. in power plants), or converted to a liquid fuel (e.g. methanol), which is relatively easy to store and transport, and can be used in motor vehicles and electricity generation facilities. The oxygen produced in the process can be used in oxy-fuel combustion or other advanced combustion methods in power plants.

In this study it is assumed that a typical sub-critical, 575 MW, coal firing power plant is converted to oxy-fuel combustion. The flue gases from that power plant are then used as raw material for fuel production. The aim of the study is to estimate the optimal conceptual design of a power generation plant, including liquid/gaseous fuel generation facility.

In the present study we used a series of special models for simulating the heat balance, heat transfer, performance and emissions of an oxy-fuel converted utility boiler. We also employed cycle simulation software that facilitates the optimization of an electricity generation plant with CO2 conversion to liquid fuel and usage of the fuel produced from CO2 for additional electricity production.

The simulation results show that the amount of fuel produced, additional power generated and power station self consumption may be changed over a wide range, depending on the size of the solar field, which provides the energy for the liquid fuel production.

The paper includes an overview of some of the key technical considerations of the new concept of CO2 conversion to fuel. Based on the obtained results it may be concluded that the methodology presented in this study is an attractive option for CO2 emission reduction, which can be implemented in existing and/or new power generation units. The technology proposed in this paper is not indented as an alternative for replacing coal combustion with natural gas, however may be used effectively with oxy-Thel combustion of either coal or natural gas.