A thermal plasma technology capable of instantaneously dissociating large carbon containing molecules directly into a mixture of ionized particles can generate energy from gases attributed to the greenhouse effect.
About 95% of the hydrogen produced today from natural gas using steam-methane reforming, an endothermic process in which high-temperature steam (700°C–1000°C) reacts with methane under 3–25 bar pressure in the presence of catalysts. Hydrogen may also be formed by utilizing the dry-reforming process. A major advantage of the dry-reforming process is that it consumes abundant volumes of environmentally detrimental gases (methane and CO2) and transforms them into clean fuel: hydrogen and CO, where CO can be further mixed with coal or biomass and used in conventional diesel engines or mixed with steam to produce more hydrogen.
Due to strong bonds between C-H atoms in methane and C-O in CO2 and its high activation energies, dry-reforming reaction finds limited practical usage. The solution for the economical utilization of the dry-reforming process is the thermal plasma technique capable of dissociating large molecules directly into a mixture of ionized particles, avoiding various energy intensive process steps. The thermal plasmas utilizing molecular gases must dissociate before ionization that translates into generation of high enthalpy and high thermal conductivity ionized gases at relatively low temperatures. The thermal conductivity of a mixture containing CO2 and CH4 in 2:1 ratio is almost 20 times greater than that of ionized argon that is often used in thermal plasma applications. In airtight reactor thermal plasmas instantaneously achieve high temperature and provide simultaneous dissociation and ionization of gases without NOx formation. Carbon containing thermal plasmas, compared to argon plasma have a considerably higher thermal efficiency, a higher concentration of H2, a low arc current and higher arc voltage, higher torch thermal efficiencies and a wider treatment area.
A crucial environmental benefit in waste to energy applications is that for a given power, it transfers more energy to treated material allowing a higher processing rate while facilitating steep temperature gradients in the plasma jet. Lower temperatures means less energy is lost in cooling the reactor and longer lifetimes of refractory material and reactor.
In the last ten years several thermal plasma plants around the world were employed for commercial generation of electricity from municipal waste using air, vaporized water and argon to generate plasma gas. They benefitted from the fact that the typical municipal waste contains more than 80% energy dense carbon containing material. A significant advantage of the proposed process is that the plasma gas itself can be transformed to syngas (CO+H2) together with C, H and O contained in municipal waste that is transformed in fuel. The energy return from higher energy value material utilizing more efficient plasma technology will be considerably higher than already commercialized energy conversion facilities.
Cost-effective conversion of natural gas into high quality fuels can reduce need for fossil fuels while economical direct reforming process might recover large quantities of gases now scattered or flared into atmosphere from combustion based processes.
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