Uwe Begander, Hans Schnitzer, Christoph Brunner, Karin Taferner JOANNEUM RESEARCH — Institute of Sustainable Techniques and Systems Graz, Austria

Introduction: Documentation of realized plants for the use of thermal solar energy in trade and industry companies. Identification of production processes and branches, which have a demand for low-temperature heat. Determine the potential of solar thermal systems to provide low-temperature heat. Case studies for branches and processes with the highest mid-term potential for realization of a solar plant.

Background

Industry is one of the great users of energy in all industrialised countries. Caused by the fact that energy is available at low costs and without limitations, industry did not care too much about energy efficiency and substitution of fossil fuels. The main activities in this field started in 1973 and 1979/80 following the two oil (price) crises. Later on, oil prices — and related to that the prices for natural gas and electricity — went down again. Today — even in the face of a possible critical political situation in the Near East — energy prices are low.

On the other hand, it is obvious that fossil resources are finite and alternatives have to be found for any application, including the use in industry and commercial applications.

More than one third of final consumption is used for space heating, hot water production, cooking and cooling, with an other quarter being used for process heat (Fickl, Stenitzer 1997). The fraction of energy going to industry is getting less, since the absolute numbers are relatively constant and diminishing related to the production.

1: Final energy consumption in the industries of special goods production according to low-temperature energy consumption (sum of steam generation and space heating & air conditioning) for the year 1998 (after statistics Austria)

In 1999 the final energy consumption of Austria was 940 PJ1 (STATISTIK AUSTRIA, WIFO 2002). 291 PJ or 28.9 % were used in industry for a wide range of use (E. V.A. 2002):

Space Heating & Cooling 19 PJ Steam Generation 68 PJ Stationary Furnaces 117 PJ Engines 57 PJ

Vehicles 21 PJ

Lighting 9 PJ

Electrochemical Purposes 1 PJ

In 1998 40 % of the Austrian final energy consumption or 356 PJ was used to produce low temperature heat (up to 100 °С)- for space heating and provision of hot water (Neubarth, Kaltschmitt 2000), more than 1/3 or 125 PJ in industrial companies. Energy sources for this range of use were oil (27%), gas (20%), coal and electricity, together nearly 2/3 fossils based, biomass (27%) and district heating. Losses in final consumption were 30%.

The amount of process heat was 199 PJ, losses were 25%. Sources were gas (40%), coal (17%), oil (15%), electricity and biomass (15%).

The final industrial consumption for process heat, space heating and the production of hot water was 324 PJ, which was 35 % of the final consumption of Austria.

R. Hofer (Hofer 1994) has analysed the different temperature levels of process heat. One of the results was, that 25 PJ of the process heat is used under 100 °С. Thus 150 PJ of low temperature heat is used in production processes in Austria. This theoretical potential is the basis for estimations that consider conditions of solar technology, process technology, economy, market and social matters.

The percentage of energy costs in industry is under 5 %, for some sectors (iron and steel, paper, foundries and non-metallic minerals) it’s about 10 % of total costs (Kaiser, Starzer 1999).

To supply solar energy to different forms of energy services, there exists a number of ways. In industry, there are different uses for energy like low temperature heat, high temperature heat, power, cooling, information and light. For the application of solar energy in countries like Austria — where there is a high fraction of diffuse light — only low temperature production processes are relevant. It is the aim of the research project “PROMISE — production with solar energy” to locate such processes, calculate the potential in Austria and to design a selected number. Estimating the potential, one has to distinguish between the technical potential, the economic potential and the market potential.

The technical potential includes all applications where existing technologies could be applied, not regarding economic questions. The economic potential includes all application, where the technologies provide a sufficient payback or at least lower costs for the supply of energy that in the existing situation. The market potential is still lower, since now all applications are excluded, where companies are not willing to invest, although the investment would be economic. There are several reasons, why a company does not invest.

First of all is the barrier of information and knowledge: the company does not know about the possibilities

Then there is the barrier of motivation: managers care only about aspects that are important to produce at a high quality and a high security Then there is the lack of capital mainly with small companies.

The work described in this paper concentrates on low temperature heat that can be supplied by means of solar radiation and solar collectors. The paper is structured in three parts: energy in sectors, energy in unit operations and examples for production processes with potential for solar heating.

Objectives

The main goals of the project were

• the documentation of realized plants for the use of solar thermal energy in trade and industry companies,

• the identification of production processes and branches which have a demand for low-temperature heat and

• the determination of the potential of solar thermal systems to provide low — temperature heat in the Austrian industry.

Methodology

The initial approach was literature investigation in the fields of solar thermal applications, heat demand and energy supply of industrial processes and energy conservation. After that questionnaires were sent to 600 industrial enterprises to scan actual conditions and requirements for energy supply.

The most important source to obtain knowledge about processes and their heat demand were several case studies for branches with the highest mid-term potential for realization of a solar plant (dairy industry, brewery, concrete processing, plastics processing, galvanizing).