Background, Aim and Scope:
In recent years growing concern over environmental issues and energy security have led to the promotion of indigenous renewable energy resources. The article presents a few technological options, namely Carbonization, for the utilization and conversion of woody biomass into useful products. The aim of the carbonization process is to convert waste wood into a solid fuel, charcoal.
Materials and Methods:
In the first stage, an LCA “gate-to-gate” system was developed for: a conventional carbonizer system, a modern carbonizer from Japan, a proposed 4-stage partial furnace carbnonizer from Tunisia. The potential environmental impacts were generated for Global Warming Potential, Acidification, Human Toxicity and Photochemical Oxidant Potential. Based on the first set of results, the second LCA investigation was carried out comparing the selected Carbonizer from Japan and an existing incinerator in Singapore. The second LCA adopted a unique approach combining social costs of pollution with the economic factors of the two biomass conversion technologies.
Results:
The Carbonizer from Japan resulted in approximately 85% less greenhouse gases than the Conventional Carbonization system, and 54% less than proposed 4-stage Carbonizer from Tunisia. For Acidification, the results for both technologies from Japan and Tunisia are nearly similar. The Human Toxicity impacts for the technology from Japan resulted in 73% less than that of the Conventional system; and 20% less than that of the proposed 4-stage carbonizer. For Photochemical Oxidant Potential, very minimal emissions are generated from the four-stage carbonizer, and nearly zero impact is realized for the carbonization technology from Japan.
Discussion:
The first set of LCA results gave a quantified assessment of the performance of three carbonizers. In terms of individual impacts such as Acidification and Human Toxicity, the carbonizers from Japan and Tunisia display nearly similar results. However, where overall performance is concerned the technology from Japan displayed environmental benefits of 7% higher. The second LCA addressed the performance of the Carbonizer from Japan against an existing incinerator in terms of environmental as well as, costs. This unique approach translated pollution emissions into monetary costs to highlight the impacts of social health.
Conclusions:
For the first LCA, the final weighted scores showed that the Carbonizer from Japan and the 4-stage carbonizer from Tunisia generated 75% and 68% less air pollution respectively, than the wood-to-charcoal conversion system. The second LCA results show a significant improvement of 90% for human health due to reduced pollution of the modern Japanese Carbonizer technology, as compared against conventional incinerators. Without considering human health (social costs), the total value per ton of wood treated is nearly similar for both Incinerator and Carbonizer.
Recommendations and
Perspectives:
Biomass is viewed as a potentially important renewable resource. However, today’s interest in biomass as raw material for producing energy is not without precedence. Careful selection of technologies are necessary before implementation of any large scales systems for biomass utilization. A full life cycle study, along with costs and the impact of pollution on society, should be performed before any large-scale biomass conversion technology is implemented. LCA can be used to confirm the overall environmental performance in a quantitative manner, as well as, further analyze the systems in terms of costs and social implications.
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