4.1 Weak points of gasifier-engine-systems

It became obvious in the late eighties that despite the lively interest in the gasifier technology during the past 10 years no "dissemination" worthwhile mentioning had taken place. The dominant argument to explain this was the claimed "technical immaturity" of the systems. This requires some comments.

It is typical for gasifiers employed in developing countries over the last years that these systems had mainly been developed by research institutions and universities. These plants (all of them prototypes) showed technical shortcomings as soon as they were tested under the rough conditions of "field application". In the end their failure consisted of a sum of mistakes made in details, which only came to light when the favourable conditions of lab application (defined and constant fuel quality, good possibilities for repair and optimization, qualified and motivated operators) were missing: Bad bunker flow of insufficiently prepared fuel, unoptimized container geometry, fast wear of parts subjected to varying temperature, wear of scalings, problems of corrosion, insufficient gas cleaning were wide-spread defects [3].

On the basis of subsequent documentation quite often it can also be reconstructed that grave mistakes have been made in the adaptation between gasifier output and engine size (usually the cylinder volume of the engine was chosen too small, thus preventing the gasifier from reaching the necessary operating temperature). Often there also existed wrong ideas about the application purposes, to which gasifiers might generally be suited or unsuited.

More will be said on the technical aspects later in this paper. First, however, another approach is chosen. The most commonly used argument of the allegedly existing technical "immaturity" of those gasifiers available certainly often holds true for some wellknown cases, but it can no longer be accepted as the sole reason for the hitherto limited dissemination. Technical problems are almost always solvable, once they have been recognized. Meanwhile, knowledge about gasifiers should be sufficient to realize good technical performance. But still the reputation of this technology is not too good.