In this section of the expert interviews series we interviewed Dipl.-Päd. Ing. Werner Weiss, founding member and managing director of AEE - Institut für Nachhaltige Technologien (AEE INTEC)
AEE - Institute for Sustainable Technologies based in Gleisdorf, was founded in 1988 as a non-university research institution and is today one of the leading institutes in applied research. AEE INTEC is concerned with research into the scientific and technical fundamentals of solar thermal energy use, with the development of low-energy and zero-energy buildings, as well as their efficient energy supply systems. The third relevant area deals with energy efficiency in industry.
In which areas do you see the future of solar thermal energy?
The great potential of solar thermal energy lies, on the one hand, in the residential building sector, on the other hand in the area of industrial process heat. There are small potentials for solar cooling.
Future developments in residential buildings will depend massively on how well the industry succeeds in reducing the system prices of solar thermal systems. These have remained stable over the past ten years. If a price reduction succeeds, combination plants with a high solar share will have very high potential, especially in the new construction sector. Under a combination or hybrid system, I understand in this case the combination of solar thermal energy and heat pump or biomass. Solarthermie is currently an add-on technology, which means that another heating system is necessary to heat a building at any time. The aim must be to provide a hybrid system that meets this requirement. Similar to photovoltaics, an attractive promoter theme, coupled with price reductions of the overall systems, could trigger a boom. Furthermore, it is crucial that the prices reached by the producers are also passed on directly to the customer, since only an increase in the demand can be stimulated.
In the private plant sector, the application will continue to be concentrated on small plants, while large-scale plants will increasingly be used in multi-storey residential buildings. Connections with district heating systems are also a type of heat supply, which can be forced by an increased use of solar thermal energy.
What are the main research areas in solar thermal energy?
A central, also international research focus is the topic of the store. The storage is the critical point when using solar thermal energy in a family house when it comes to generating a heat-generating system. The water reservoirs currently in use have a too low energy density for a heat-efficient operation. For this reason, a number of projects were initiated to save energy with high energy densities. Examples include sorption storage, thermochemical storage or phase change storage (latent heat storage). In the demonstration area there will already be first applications in the next 1-2 years, on the market the technology will be available in the next 3-5 years. The loss of a backup system will significantly reduce costs, which could significantly increase the demand for solar thermal systems.
In addition to storage mathematics, research is being carried out on new materials, for example in the polymer processing sector. The aim of these researches is to make the whole system more cost-effective. Furthermore, the integration of solar thermal energy into intelligent networks (combined thermal and electrical networks) is being intensified.
What are the main advantages of using solar thermal energy to provide process heat?
In addition to environmental considerations, the efficiency of the plants is a decisive factor for companies. This is given under certain conditions. Solarthermie is already used in many cases to generate process heat. Solarthermie is particularly interesting for those companies that are planning to spend longer periods in one location, depending on the plant and the load profile, payback times are around 5-7 years. Companies in the food industry, such as breweries or dairies, have a very high potential for solar thermal applications, as the processes are well suited for this, and on the other hand, companies expect to be produced at this location within 10 years. This is not always the case in the textile industry. A significant advantage for companies is that, after the end of the amortization period, the heat energy is transferred to the zero tariff until the end of the life of the plant, apart from the low maintenance costs. For the entire duration of the plant, energy is thus provided by solar thermal energy around 2/3 cheaper than with conventional energy sources, the price increases of which do not yet include.
Do you see a growing interest of the industry in solar thermal?
We recognize the trend that more and more companies are interested in this topic and are involved in their deliberations. Numerous events provide information on the application of solar thermal energy in production practice. In addition to the provision of heat, measures of energy efficiency are also considered in this context. The reduction of heat demand is the focus, for example, by switching from a steam system to a hot water system. The subsequent combination of these measures with solar thermal energy also makes the whole system more interesting.
What is needed to implement the technology of a wide application are large, already implemented, functioning plants. These are particularly important for companies as they prove in practice that this technology is economically applicable. For this reason, a functioning, sufficiently large domestic market is of great importance.
A subsidy based on the installed plant area, irrespective of the actual yield or irrespective of the efficiency of the plant, is overtaken and should be adapted accordingly. The quality of the system has to be integrated into the support regimen.
What are the prerequisites for the use of solar thermal energy in a company?
Particularly advantageous is a heat demand which exists all year round and is continuously present. It would be optimal if the demand for heat in summer is higher than in winter, but this is by no means a prerequisite for the economic operation of a system. Temperature ranges from 60 ° C to 100 ° C are well suited for solar thermal heating.
Which innovative operating models for solar thermal systems, for example for process heat, are there or will be in the future?
A potential opportunity to operate a large plant is via contracting models, but a further consideration of the solar thermal system prices is necessary to make this business model even more attractive and to be applied in its breadth. In addition, it is possible to build and operate solar thermal systems by third parties by leasing their own roof surfaces. Compared to photovoltaics, however, the possibilities for earthmoving are less favorable since the places of production and consumption of heat energy must be closer together. The same applies to the operation of an installation in the form of joint facilities.
What would be necessary in order to integrate the solar thermal energy into operational processes?
In other countries, such as Denmark, there are companies that offer turnkey facilities. The handling of the plant installation by only one company makes it easier for a potential customer to plan and set up the plant. In Austria there are a number of companies (planners, producers, assembler, intallators, etc.) who need to be coordinated to a certain extent. This development, which has contributed to the success of many domestic companies in recent years, has turned out to be a certain disadvantage in the course of the economic crisis. It would be a new kind of company, with know-how in plant construction, necessary to counter this development.
How will the domestic solar energy sector be represented in an international comparison in the coming years?
In the past, the domestic sector was one of the European leaders with the German industry, with a still high export rate of around 80% proving this. In the future, the price of the systems will be decisive. If no relevant price reductions are achieved, similar to photovoltaics there is the risk that foreign companies can offer facilities more favorably and damage the dometsic industry.
Gründungsmitglied und Geschäftsführer von AEE - Institut für Nachhaltige Technologien (AEE INTEC)
seit 2010: Vorsitzender des IEA Solar Heating and Cooling Programme
seit 2010: Vorstandsmitglied der Europäischen Technologieplattform für Heizen und Kühlen mit Erneuerbaren Energieträgern
federführende Mitwirkung an der Entwicklung der Europäischen Forschungsagenda für Solarthermie
seit 2007: Lehrbeauftragter an der Technischen Universität Wien
seit 2007: Mitglied des Peer Review College of the Danish Council of Strategic Research