Four distinct aspects of technology performance influenced the technology diffusion quite differently: performance of the central heating plant with respect to the reliability of the operations, performance with respect to emissions, the technical interface with heat consumers, and overall systems efficiency.

Reliable operation was a major preoccupation to operators in the beginning. It did not influence diffusion significantly because the proud plant owners were secretive about operation problems. Due to their technical versatility, they managed to overcome daily problems. Customers usually do not notice central plant failures of a few hours only, due to the heat capacity of the hot water in the grid.

A close follow-up of the problems faced in the plants was carried out with the equipment providers with the help of the supporting organizations and the so-called technology introduction managers. This contributed to learn-by-doing and led to the necessary technological improvements for reliable plant operation. Figure 4.1 shows the effect of the process of technological learning. The percentage of plants with serious operation problems dropped sharply after the initial years of the technology dissemination. By the mid-1980s, almost one-third of the plants were problem-free.

The second aspect of technology performance was related to emissions from the heating plant. In the early 1980s, emissions played a secondary role in the public perception of technology performance. Nevertheless, a publicly funded R&D pro­gram was carried out and this led to the deployment of emissions mitigating equipment employing continuous power control, electronic combustion control and, in the early 1990s, flue gas condensation. The attention given to the issue of emissions was worthwhile as the technological improvements achieved favored further dissemination of district heating plants, particularly in the 1990s when environmental awareness became more widespread.

The greatest threat to the district heating technology diffusion came from deficiencies in the technical interface between the district heating grid and the

individual house-heating systems. Failures in this subsystem directly affect consumer comfort. This interface, including for example the heat exchanger and pipes, is not a part of the BMDH plant. Normally, the equipment was planned, installed and maintained by independent local plumbers, who did not have any particular experience with district heating. In some cases, plumbers repeated the same mistakes in many installations in a single district, which seriously affected the local reputation of biomass district heating. It so happened that plants could not be established in neighboring villages due to the bad reputation created.

The last technical aspect is the overall plant performance. While considerable R&D efforts were made to minimize emissions, overall technical performance of the system was largely neglected. Even today, the annual system efficiency is only around 50 per cent in many plants. Heat losses and high electricity costs occur due to oversized boilers, badly maintained district heating pipes and electric pumps, vents, etc. Operators were seldom aware of the high heat losses and electricity costs of their plants and understood these technical problems to be an economic problem related to competition with low oil prices. Since no public attention was paid to monitoring technical overall performance and as the operators did not properly understand such problems, no feedback reached the responsible technical planners. This slowed down technological learning considerably.

Figure 4.2 shows the specific electricity costs of plants installed between 1984 and 1993. As can be seen from the figure, there was no noteworthy technological learning in this period. It is significant to notice that the electricity costs for delivering 1 MWh of heat to customers varies widely, that is, from 15 to 150 ATS 2 per MWh between the best and the worst plants. [5]

It is difficult to quantify what impact the deficiencies in planning and operation had on the dynamics of technology diffusion. They certainly led to unnecessary costs and management problems. Politicians managed to prevent open financial disasters by asking public utilities to take over plants with serious problems. Proactive policies to upgrade plants technically were only put in place 20 years after diffusion kick-off with the introduction of technical quality criteria as precondition for subsidies.

Thus lack of qualification among relevant professionals such as plumbers, plan­ners and plant operators was a major technical obstacle for biomass plant diffusion in Austria. This is important to emphasize as there is a tendency to focus attention on the technical device per se and less so on what is considered more peripheral such as technology interface and professional skills. Feedback at all points along the energy generation and distribution chain is fundamental for technological learning. Putting in place appropriate feedback mechanisms should therefore be regarded as a central task for renewable energy management.