|Application of Biomass Energy Technologies (HABITAT, 1993, 168 p.)|
|VI. CONVERSION OF BIOMASS INTO ELECTRICITY|
The island States of the South Pacific are generally dependent on imported fossil fuels. Due to the high oil prices in the early 1980s and plentiful indigenous biomass resources (on the larger islands), there was considerable interest in installing biomass gasification units for electricity production and crop drying. Available resources include residues from over 600,000 ha of copra plantations and almost 44.5 million ha of forested areas (Sanday and Lloyd, 1991). The main impetus for the introduction of power gasifiers into the South Pacific region was the European Community-funded Lome II Pacific Region Energy Programme (PREP) in 1983/84. This proposed, and budgeted for, 17 gasifier projects, but finally, only two were installed, both considerably reduced in scale, capacity and cost relative to the original proposals. Other gasifier units were also installed privately in the region. Sanday and Lloyd (1991) of the Energy Studies Unit (ESU) at the University of the South Pacific carried out a survey and monitoring programme of all power and heat gasifiers. They found that of the 16 power gasifiers installed altogether, only one was known to be still operating satisfactorily, the rest having ceased operation. Similarly, for the Waterwide heat gasifiers installed in Papua New Guinea, only 20 out of 80 were still in use in January 1990, and most of the other documented heat gasifiers in this region were also expected to have shut down.
The operational problems were thought mainly to be due to flaws in original designs resulting in shortened plant lifetime. The systems installed experienced severe operational and design problems that should have been solved prior to installation in remote sites. To Sanday and Lloyd (1991, p. 17) it seemed
that the Pacific Islands have been used as experimental stations for technologies that have not been proven in industrial countries. (Furthermore,) gasifiers have often quickly deteriorated resulting from mismanagement of operational and maintenance procedures, and the persisting hostile operational environment.
Most of the manufacturers were external to the region, some based as far away as Europe. Therefore, there was a lack of spare parts and skilled technicians to carry out maintenance and repair work. This situation was exacerbated by the fact that five of the six manufacturers who supplied systems to the region in the last decade went out of business. There was also a lack of infrastructure support within the region as personnel trained in gasifier technology were extremely scarce, so ordinary mechanics and technicians were often called on to carry out repair work with limited success. Since the gasifier locations were scattered amongst different islands it was difficult and costly to locate maintenance services and they could not be promptly available. Information on the technology was limited and usually in the form of papers for academics and other technical personnel rather than being designed for potential end-users.
The availability of biomass feedstocks may have been over-estimated originally, and the quality these feedstocks and their erratic supplies resulted in intermittent gasifier operation with some systems being periodically shut down. The shortages due to lack of fuelwood supplies were compounded by domestic cooking receiving priority, difficulties associated with land availability and ownership, and soil salinity problems when replanting programmes were used (Sanday and Lloyd, 1991, p. x). Also, lacking were schemes to collect scattered fuel and the failure to implement tree replanting programmes. Furthermore, the Waterwide heat gasifiers experienced problems with smoke contamination affecting the quality of dried agricultural products and causing heavy financial losses; this was mainly due to improper use.
Repetitive breakdowns and lack of maintenance support meant gasifier operators usually preferred to choose diesel systems which had been proved to be relatively successful and user-friendly in such situations. Furthermore, initial capital costs of gasifiers were high and unable to compete with equivalent diesel sets at current diesel fuel prices. All the problems experienced appear to have discouraged further developments towards implementation of gasifier technology in the region. Most success was found with small wood and husk-fuelled gasifiers installed in Papua New Guinea for agro-drying applications. The single power gasifier that was still operational, a BECE unit in Vanuatu, connected with a school, was successful due to the availability of wood fuels, the commitment of the operators and the school management and the fortune to have a very gifted and enthusiastic support staff as one of the teachers at the school.