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In analogy to electricity transmission networks, this paper analyzes the concept of supra-regional district heating networks (SR-DHN), connecting a large number of actors. Using a back-casting approach, a SR-DHN is assumed to exist and thus, implementation challenges, such as economic feasibility and energy losses, are circumvented in the first step (but are analyzed in the discourse). The paper then analyzes, in an interdisciplinary qualitative manner and supported by a case study, what technical, operational, economic and legal issues must have been resolved. Results show that the heat transmission network, being the backbone of the SR-DHN, is an expensive infrastructure, but is likely to become economic in a non-fossil energy system. By decreasing the reliance on single waste heat sources, SR-DHN allows longer payback periods and can thus be an enabler for using industrial waste heat. However, involving many actors requires comprehensive contractual foundations. The derived hypothesis is that SR-DHN, which is predominantly fed by waste heat, shall be operated with lower temperatures in winter (feeding the return while minimizing expensive winter losses) and high temperatures in summer (enabling alternative usages while accepting high but inexpensive summer losses).

Despite large amounts of available roof space, long pay-back periods for investments in photovoltaic (PV) power plants often hinder PV installations in industrial parks. Photovoltaic citizen participation initiatives (PV-CPI) are an alternative way of financing PV power plants that add non-financial benefits to these investments. This paper analyzed the feasibility of the installation of PV power plants focused on high rates of self-consumption financed by citizen participation initiatives on the roofs of five companies located in the Austrian Ennshafen industrial business park based on the net present value and the discounted pay-back period and compared it to a standard financing scheme, assuming a predetermined interest rate for participants as well as economies of scale with respect to the specific installation costs due to a joint purchase of the PV power plants. To calculate the feasibility, site-specific data and literature input have been used. The results show that despite an interest rate above the current interest rates of conservative forms of investments provided to (small-scale) investors, a payback-period of 17–23 years can be reached while the joint purchase can lead to a competitive feasibility of the PV-CPI compared to an individual purchase of PV power plants.