THE CARNOL SYSTEM FOR METHANOL PRODUCTION AND COz MITIGATION FROM COAL FIRED POWER PLANTS AND THE TRANSPORTATION SECTOR

The Camol System consists of methanol production by CO, recovered from coal fired power plants and natural gas and the use of the methanol as an alternative automotive fuel. The Carnol Process produces hydrogen by the thermal decomposition of natural gas and reacting the hydrogen with CO, recovered from the power plant. The carbon produced can be stored or used as a materials commodity. A design and economic evaluation of the is presented and compared to gasoline as an automotive fuel. An evaluation of the CO, emission reduction of the process and system is made and compared to other conventional methanol production processes is including the use of biomass feedstock and methanol fuel cell vehicles. The CO, for the entire Camol System using methanol in automotive IC engines can be reduced by 56% compared to conventional system of coal plants and gasoline engmes and by as much as 77% CO, emission reduction when methanol is used in fuel cells in automotive engines. The Camol System is shown to be an environmentally attractive and economically viable system connecting the power generation sector with the transportation sector whch should warrant M e r development. INTRODUCTION Coal and natural gas are abundant fuels. Because of their physical and chemical properties, coal and natural gas are di€Iicult to handle and u&e in mobile as well as stationary engmes. The infirastructure is mainly geared to handle clean liquid fuels. In order to convert coal to liquid fuel, it is generally necessary to increase its WC ratio either by increasing its hydrogen content or decreasing its carbon content. On the other hand, in order to convert natural gas to liquid fuels it becomes necessq to decrease its hydrogen content. Thus, by coprocessing the hydrogen-rich natural gas with hydrogen deficient coal, it should be possible to produce liquid fbels in an economically attractive manner. For environmental purposes of decreasing CO, greenhouse gas emissions, several approaches can be taken. The C0,emission from central power stations can be removed, recovered and disposed of in deep ocean.(') Alternatively, carbon can be extracted from coal and natural gas and only the hydrogen-rich fractions can be utilized from both of these fuels to reduce CO, emissions while storing the carbon.@) Because of its physically properties, carbon is much easier to dispose of either by storage or used as a materials commodity than sequestering CO,.(') A third alternative CO, mitigation method is to utilize the stack gas CO, from coal burning plants with hydrogen obtained from natural gas to produce methanol, which is a well-known liquid automotive fuel. In this paper, we describe and evaluate the Carnol Process,(3) which connects the power generation sector with the transportation sector resulting in an overall CO, mitigation system. THE CARNOL PROCESS The Cam01 Process is composed of three unit operations described in the following. 1. Carbon dioxide is extracted flom the stack gases of coal fired power plants using monoethanolamine (MEA) solvent in an absorption-stripping operation. The technology for this operation is well known in the chemical indushy for CO, recovery and has recently been si&icantly improved upon for use in extracting CO, from power plant stack gases.'4) The power required to recover CO, from an integrated coal fired power plant to recover 90% of the CO, h m the flue gas can be reduced to about 10% of the capacity of the power plant. However, this energy requirement can be reduced to less than 1% when the CO, recovery operation is integrated wth a methanol synthesis step described in plant 3 below. The hydrogen required to react with CO, for producing methanol can be obtained from either of two methcds involving natural gas. In the conventional methcd for producing hydrogen natural gas is reformed with steam, CH, + 2KO = CO, f 4%. Thls process produces CO, and, thus, CO, emission is increased. However, hydrogen can be produced without CO, emission by the non-conventional method of thermally decomposing methane to carbon and hydrogen; CH, = C + 2%. 2. This work was performed under the auspices of the U.S. Department of Energy.