UNIDO trials sisal waste for biogas and biofertilizer

Tanzania has registered considerable success in testing the use of sisal waste in generating electricity. An ongoing pilot project managed by the United Nations Industrial Development Organization (UNIDO) titled 'Cleaner Integral Utilisation of Sisal Waste for Biogas and Biofertilizers' shows that the sisal residues make for an efficient substrate for anaerobic digestion. The biogas waste stream makes for a bio-fertilizer.

Sisal is an agave that yields a stiff fiber used for a range of products, most notably rope and industrial fibers. In the 1970s, global production was about 800,000 tonnes with Kenya and Tanzania accounting for over 30 percent of the total. Other sisal growing countries are China, Brazil, Mexico, South Africa and Mozambique. In 2006, global production had plummeted to about 268,000 tonnes. The downtrend in sisal production has been attributed to the emergence of synthetic fibers made from petroleum, to poor marketing arrangements, barriers to free trade, non utilization of the entire sisal plant and inadequate research and development.

However, recent interest in natural fibers as replacements for petroleum-based synthetics has given the African sisal industry renewed vigor. Car manufacturers as well as green product designers are looking back into the crop (earlier post).

The more efficient utilization of the entire plant's waste stream could further contribute to reviving the industry. Until recently only 2% of the sisal plant was considered to be useful. New initiatives, amongst which the UNIDO project, now show that the remaining 98 percent has potential economic value; harvesting and processing residues, discarded in the past, now have use as a biomass feedstock capable of yielding renewable and carbon-neutral energy.

The UNIDO project involves a biogas pilot plant at the Hale Sisal Estate in the Korogwe District in the Tanga region, which was able to yield 150 kilowatts of electricity from the plantation's harvesting and processing residues, enough to power a nearby hammer mill for making pulp.

Mayra Sanchez Osuna, UNIDO's Project Manager said the trials have established the viability of using sisal waste to produce the biogas, electricity and bio-fertilizer:

[this] is the first demonstration project for the total utilization of this commodity in an economically feasible and friendly way adding that the results will be transferred to other interested sisal growing nations to replicate.

Observers say the findings will check the power divide existing between the rural and urban communities. Osuna said that the positive effect was leading to possibility of generating electricity in rural areas from locally available renewable sources:
energy :: sustainability :: biomass :: bioenergy :: biofuels :: biogas :: sisal :: natural fiber :: Africa ::

More than half of the world population has no access to electricity and with the prices of fuel rising relentlessly the search for alternative energy becomes crucial.

The Hale project is part of the efforts to find for alternative applications of sisal to counter the present slump in sisal fibre sales after the introduction of synthetic fibres in the international markets.

Patricia Scott, UNIDO representative in Tanzania said it became clear that the future of the sisal industry depend on the diversification of its uses.

Counting the advantages of sisal biogas utilization she said it adds value to the sisal waste, it solves environmental problems related to the disposal of the waste, it generates energy to be used in the sisal industry, yields a valuable biological fertilizer, and it reduces greenhouse gas emissions.

The Project cost was estimated at US$1,5 million. Financiers include the Common Fund for Commodities (CFC), UNIDO, the Tanzanian Government and privately owned company Katani Limited.

References:
East African Business Week (via AllAfrica): Dar Plans Power From Sisal Waste - October 1, 2007.

Biopact: The bioeconomy at work: oil crisis boosts African sisal industry - December 18, 2006