Assessment of economical biogas production from chilean municipal solid waste in a decentralized off-grid strategy

The management of municipal solid waste (MSW) is one of biggest challenges that developing countries are currently facing. Despite several environmental friendly alternatives being available, in Chile 90 % of MSW is disposed of in landfills, which produces large amounts of greenhouse gases (GHG) by the uncontrolled anaerobic digestion of its organic fraction. In addition, the way in which MSW is collected and transported increases the negative impact to the environment, especially when wastes classification is not properly performed at the generation point. On the other hand, the use of resulting biogas, in a decentralized off-grid form, at the generation point, could directly reward to waste producers with economic saving. This strategy will reinforce population motivation and an important reduction of the GHG emissions can be expected. Thus, this paper explores the biogas potential of food wastes by using reactors with no heating and stirring devices, with the aim of assessing the minimum expectable energy and CO2,eq savings. Based on laboratory tests at batch and semi-continuous mode and Chilean historical data, it is concluded that more than 1,704 Gg of CO2,eq can be avoided per year and an average of 425 GWh primary energy may be saved by Chilean householder

The Lewis Hoard of Gaming Pieces: a re-examination of their context, meanings, discovery and manufacture

ALMOST 180 YEARS of scholarship on the Lewis chessmen have given us a solid foundation of understanding, primarily based upon their art-historical analysis. Taking a more interdisciplinary approach (combining elements of art history with archaeology and history), this paper focuses on some over-looked themes — primarily the archaeological, gaming and political contexts of the 12th- and 13th-century North Sea world — and some more familiar themes but in a new light. We suggest a more fluid composition and function of the gaming hoard,with at least four sets of chessmen from the same workshop conceivably made for use in Lewis, possibly in the early 13th century