The possibility to couple a large-scale solar tubular reformer (a chemical reactor where a low hydrocarbon, e.g., methane, is reacting with steam and/or CO2 to produce synthesis gas, a mixture of carbon monoxide and hydrogen), with a solar tower beam-down optics, is explored and analyzed. The reformer is installed on the ground and the concentrated solar energy enters through an aperture in the ceiling of the reformer enclosure and heats the reactor tubes, arranged within the enclosure along its walls. This arrangement enables, potentially, to adapt a large solar plant to a modified conventionally designed reformer. Through an example where about 50 MW of solar energy is introduced into an array of ground reformers, the optical path and the radiative heat exchange within the reformer cavity, coupled with the reactor tube side, are calculated and illustrated. Detailed calculation results describing the radiation flux profile inside the cavity, the surface temperatures of the reactor tubes and the composition of the process gas along the tubes, as well as the annual performance of the reformer, are shown. The results demonstrate that the solar reformer illustrated in this study can be connected to a combined cycle-power generation unit having a nominal capacity of 100-MW electricity. A power generation unit of this kind, if operating annually during roughly 2000 sunny hours, will produce about 25% of its power, supplied by the solar energy source. (C) 2003 Elsevier Ltd. All rights reserved.