An energy system including a converter disposed within a collection vessel for collecting exhaust generated by the converter for delivery, if desired, to a bottoming device, such as a gas turbine assembly. The converter can be operated as a reformer. The chemical converter may also be operated as an electrochemical device. When the converter is operated as a fuel cell, electrical energy is generated when supplied with hydrogen or a hydrocarbon fuels. When operated as an electrolytic cell, the electrical energy is consumed for the production of chemical feed stocks or media for storage. The energy system can also include or be used as a thermal plant for producing pressurized, superheated vapor, or a hot thermal fluid or gas medium for commercial, industrial or power generation uses.