An Italian researcher designed and patented an innovative system: core innovation is based on the idea to use the heat contained in the exhaust gases of a modified gas turbine to obtain thermal dissociation of water through the sulfur-iodine cycle and to produce oxygen and hydrogen gaseous.
This combined-cycle gas-turbine / steam-turbine modified system enables the production of electricity with greater efficiency than currently available and drastically reduces CO2 emissions.
With the European project H2-IGCC (Combined Cycles Gasification Plants), a consortium was set up to provide technical solutions that allow the highly efficient use of the partially hydrogen-powered gas turbine. The study and demonstration of feasibility were planned by 2010, while the organization for commercial distribution is scheduled for 2020.
The project has brought significant results in the material selection process and will contribute in the future to the mixing of fuels. The main challenges to face are the increase in water vapor and the corrosion at high temperatures caused by the enrichment of the fuel with hydrogen. With the development of the life expectancy of the NDE methods, the project substantially reduced the risks assumed by the IGCC gas turbine design process.
However, this project does not refer to hydrogen procurement systems.
Given the good results offered by the project and in view of the fact that at this time the cost of hydrogen is very high, it is proposed to use the same gas turbine exhaust to produce hydrogen through the thermal dissociation of water in a cycle that does not produce substances harmful to the environment and has lower costs than those of fossil fuels.
The researcher developed a study for the production of hydrogen through thermal dissociation of water using the residual heat in the fumes at the gas turbines exhaust.
In this study a continuous regeneration of the compressed air is foreseen, an increase in the mass flow of the fumes, a continuous thermal regeneration in the turbine, a higher temperature at the turbine exhaust that allows their use for thermal dissociation of the water.
All these improvements in the thermal cycle lead to an increase in overall plant yield and a reduction in CO2 emissions.
The use of the hydrogen produced in the same plant considerably increases its efficiency and drastically reduces CO2 emissions.
The system can be used to produce electricity or to sell pure hydrogen and oxygen.
The thermal balance of the proposed system is shown as an annex where the thermal exchanges of the cycle can occur. In it the quantity of thermal energy used and the electrical energy obtained can be numerically verified. Methane has been defined as the main fuel and the reduction in CO2 emissions is documented with the use in the same gas turbine of the produced hydrogen. The plant performances can be calculated numerically from the balance sheet or evaluated with the attached compression and expansion diagrams. It is possible to see in each point of the compressor and the turbine the thermal state of the fluid and the effect obtained with the injection of water for cooling the compressed air and the effect of fuel / hydrogen injection into the turbine for increase the specific volume of the fumes and therefore the efficiency of the turbine. The attached figure 3 shows the vapor expansion in the water vapor turbine, highlighting its efficiency.
At present the idea is at the level of a theoretical proposal with a scientific demonstration of its feasibility. However, it should be remembered that to date there are no studies and/or projects for the use of turbine exhaust gases to produce hydrogen and oxygen. The researcher would like to find partners able to test and manufacture the system or research centers interested in further developing the idea under a research cooperation agreement.