Solar thermal power plants are presently the cheapest technology for solar electricity production. Today, level electricity costs of 15 ct/kWh are achievable at good sites with high levels of direct normal irradiation. Nevertheless, further cost reductions are necessary to make solar thermal power plants economically feasible. One possibility for a further cost reduction might be the use of so-called Linear Fresnel Collectors in solar thermal power plants. Preliminary cost estimates of this option show that this is a promising potential for cost reduction. The technical feasibility of the linear Fresnel collector has to be checked in theoretical studies as well as during the operation of a life-sized prototype under real solar conditions. This paper presents results of preliminary theoretical studies regarding the thermal load of the absorber tube used in a linear Fresnel collector with a secondary concentrator.