A power-generating system is provided for operating adiabatically and reducing emissions of greenhouse gases contributing to global warming. The system may include gas reactors and/or combustors that burn a fuel and an oxygen-containing gas under substantially adiabatic conditions such that high-pressure combustion products and low pressure combustor housing cooling air are combined to produce a medium pressure working fluid. Higher thermal efficiencies reduce emissions of greenhouse gases. Products of combustion can be processed to further reduce emissions of carbon dioxide and other greenhouse gases from portable and stationary exhaust-producing devices using different fuels. The system may also include solar collectors that pick up a spectrum of solar energy by means of cells containing fluids, aligned to concentrate the solar rays. The collectors may pick up direct and/or diffused solar radiation and can be used to power self-propelled vehicles or function as a roof of a building.