An auxiliary power system for providing electrical power and heat to an indoor area includes an external combustion engine, such as a Stirling cycle engine (101), for generating mechanical energy and thermal energy. The external combustion engine (101) burns a fuel with substantially complete combustion such that exhaust emissions from the external combustion engine (101) are below a predetermined exhaust level. A generator (102) is coupled to the external combustion engine (101) and converts the mechanical energy produced by the external combustion engine (101) to electrical power. A first power output is used to provide the electrical power produced by the generator (102). The external combustion engine (101) and generator (102) are disposed within a housing such that the external combustion engine (101), generator (102) and housing combination is a portable size. The thermal energy generated by the external combustion engine (101) may be used to heat the atmosphere surrounding the housing.