Influence of Reactor Design on Product Distributions from Biomass Pyrolysis

This paper explores the elements of experimental design that affect outcomes of pyrolysis experiments. Primary pyrolysis products are highly reactive, and reactor properties that tend to promote or suppress their secondary reactions play a key role in determining final product distributions. In assessing particular experimental designs, it is often useful to compare results from different configurations under similar experimental conditions. In the case of pure cellulose, char yields from pyrolysis experiments were observed to vary between 1 and 26%, as a function of changes in reactor design and associated operating parameters. Most other examples have been selected from the pyrolysis of ligno-cellulosic biomass and its main constituents, although relevant data from coal pyrolysis experiments have also been examined. The work focuses on identifying the ranges of conditions where diverse types of reactors provide more dependable data. The greater reliability of fluidized-bed reactors for weight loss (total volatile) determinations in the 300–550 °C range, particularly relevant to the study of biomass pyrolysis, has been highlighted and compared with challenges encountered in using wire-mesh reactors and thermogravimetric balances in this temperature range

Identifying Synergistic Effects between Biomass Components during Pyrolysis and Pointers Concerning Experiment Design

A review of existing data has shown that “char yield deficits” develop during the pyrolysis of lignocellulosic biomass, relative to char yields expected from pyrolyzing chemically isolated lignins and the proportion of lignin in the particular biomass. This paper describes two sets of pyrolysis experiments. The work done in a thermogravimetric (TG) balance was initiated to probe whether diminishing heating rates might reduce, or even wipe out, the “char yield deficits” identified in previous work, where a wide range of heating rates had been used. Experiments were performed at 2 °C min–1, a lower heating rate than that has hitherto been used to investigate char deficits. The effect was confirmed at this slow heating rate, using samples of birchwood and almond shells. A parallel set of differential scanning calorimetry (DSC) experiments provided evidence that mechanisms by which biomass samples pyrolyze are distinct from those of biomass components pyrolyzing in isolation. Moreover, the observed effects could not be replicated by simply mixing the three biomass components in appropriate proportions. The “lignin char deficit” is consistent with chemical interactions between intermeshed biomass components during pyrolysis altering reaction pathways and product distributions relative to the pyrolysis of biomass components pyrolyzed in isolation. The present work also shows that sample mass loss in TG balances is affected by altering sample loading, leading to potential errors. The design of pyrolysis experiments is discussed and approaches are suggested to prevent masking of key pyrolysis phenomena, viz. synergistic effects between biomass components or onset-of-pyrolysis temperatures, through the appropriate selection of experimental parameters

Liquid biofuels from food crops in transportation – A balance sheet of outcomes

The production and utilization of biofuels from food crops have been reviewed. Developments in Brazil, the United States, the European Union and China have been assessed in relation to the aims of biofuels policies, their costs and outcomes. The energy input for making biofuels has been compared with energy released during their combustion. The effect of using crops for fuel on the cost of grain for food and of arable land have been examined. There is evidence that current international policies have caused environmental degradation greater than the fossil fuels they were purported to replace. However, policy choices are difficult to reverse. Despite vast effort and expense, the actual scale of biofuels production is small compared to the resources that have been mobilized. As these processes have evolved, new groups of commercial interests have coalesced internationally, to take advantage of the subsidies with little recognizable benefit to the environment

Liquid Biofuels from Food Crops in Transportation – A Balance Sheet of Outcomes

The production and utilization of biofuels from food crops have been reviewed. Developments in Brazil, the United States, the European Union and China have been assessed in relation to the aims of biofuels policies, their costs and outcomes. The energy input for making biofuels has been compared with energy released during their combustion. The effect of using crops for fuel on the cost of grain for food and of arable land have been examined. There is evidence that current international policies have caused environmental degradation greater than the fossil fuels they were purported to replace. However, policy choices are difficult to reverse. Despite vast effort and expense, the actual scale of biofuels production is small compared to the resources that have been mobilized. As these processes have evolved, new groups of commercial interests have coalesced internationally, to take advantage of the subsidies with little recognizable benefit to the environment

Co-firing of biomass and other wastes in fluidised bed systems

A project on co-firing in large-scale power plants burning coal is currently funded by the European Commission. It is called COPOWER. The project involves 10 organisations from 6 countries. The project involves combustion studies over the full spectrum of equipment size, ranging from small laboratory-scale reactors and pilot plants, to investigate fundamentals and operating parameters, to proving trials on a commercial power plant in Duisburg. The power plant uses a circulating fluidized bed boiler. The results to be obtained are to be compared as function of scale-up. There are two different coals, 3 types of biomass and 2 kinds of waste materials are to be used for blending with coal for co-firing tests. The baseline values are obtained during a campaign of one month at the power station and the results are used for comparison with those to be obtained in other units of various sizes. Future tests will be implemented with the objective to achieve improvement on baseline values. The fuels to be used are already characterized. There are ongoing studies to determine reactivities of fuels and chars produced from the fuels. Reactivities are determined not only for individual fuels but also for blends to be used. Presently pilot-scale combustion tests are also undertaken to study the effect of blending coal with different types of biomass and waste materials. The potential for synergy to improve combustion is investigated. Early results will be reported in the Conference. Simultaneously, studies to verify the availability of biomass and waste materials in Portugal, Turkey and Italy have been undertaken. Techno-economic barriers for the future use of biomass and other waste materials are identified. The potential of using these materials in coal fired power stations has been assessed. The conclusions will also be reported

Women bargaining with patriarchy in coastal Kenya:contradictions, creative agency and food provisioning

Gender analysts have long recognised that challenging existing patriarchal structures involves risks for women, who may lose both long-term support and protection from kin. However, understanding the specific ways in which they ‘bargain with patriarchy’ in particular contexts is relatively poorly understood. We focus on a Mijikenda fishing community in coastal Kenya to explore contradictions in gendered power relations and how women deploy these to reinterpret gendered practices without directly challenging local patriarchal structures. We argue that a more complex understanding of women’s creative agency can reveal both the value to women of culturally-specific gendered roles and responsibilities and the importance of subtle changes that they are able to negotiate in these. With reference to food provisioning, the analysis contributes to more nuanced understandings of gendered household food security and women’s creative approaches to maintaining long-term security in their lives

Contract Farming, Ecological Change and the Transformations of Reciprocal Gendered Social Relations in Eastern India

Debates on gender and the commodification of land highlight the loss of land rights, intensification of demands on women’s labour, and decline in their decision-making control. Supported by ‘extra-economic forces’ of religious nationalism (Hindutva), such neoliberal interventions are producing new gender ideologies involving a subtle shift from relations of reciprocity to those of subordination. Using data from fine grained fieldwork in Koraput district, Odisha, we analyse the tensions and transformations created jointly by corporate interventions (contract farming of eucalyptus by the paper industry) and religious nationalism in the local landscape. We examine how these phenomena are reshaping relations of asymmetric mutuality between nature and society, and between men and women

Living Law, Legal Pluralism, and Corruption in Post-Soviet Uzbekistan

This paper aims to explore the multifaceted meaning, logic, and morality of informal transactions in order to better understand the social context that informs the meaning of corruption and bribery in post-Soviet Uzbekistan. It will be argued that the informal transactions in Uzbek society reflect different cultural and functional meanings from those in most of the Western world, and hence transactions that from a Western-centric perspective would be labelled as bribes can be morally accepted transactions in the Uzbek cultural context. If this is true, there may be reasons to re-evaluate the relevance of the Western-centric interpretations of corruption in the context of Uzbekistan, and possibly other Central Asian countries. These issues will be investigated with reference to observations and informal interviews from post-Soviet Uzbekistan. This study is based on three periods of ethnographic field research between 2009 and 2012 in the Ferghana Province of Uzbekistan. It draws on concepts of ‘living law’ and legal pluralism to provide a theoretical framework

‘How can I be post-Soviet if I was never Soviet?’ Rethinking categories of time and social change – a perspective from Kulob, southern Tajikistan

Based on anthropological fieldwork conducted in the Kulob region of southern Tajikistan, this paper examines the extent to which the existing periodization ‘Soviet/post-Soviet’ is still valid to frame scholarly works concerning Central Asia. It does so through an analysis of ‘alternative temporalities’ conveyed by Kulob residents to the author. These alternative temporalities are fashioned in especially clear ways in a relationship to the physical transformations occurring to two types of housing, namely flats in building blocks and detached houses. Without arguing that the categories ‘Soviet’ and ‘post-Soviet’ have become futile, the author advocates that the uncritically use of Soviet/post-Soviet has the unwanted effect of shaping the Central Asian region as a temporalized and specialized ‘other’

Bringing analysis of gender and social–ecological resilience together in small-scale fisheries research: Challenges and opportunities

The demand for gender analysis is now increasingly orthodox in natural resource programming, including that for small-scale fisheries. Whilst the analysis of social–ecological resilience has made valuable contributions to integrating social dimensions into research and policy-making on natural resource management, it has so far demonstrated limited success in effectively integrating considerations of gender equity. This paper reviews the challenges in, and opportunities for, bringing a gender analysis together with social–ecological resilience analysis in the context of small-scale fisheries research in developing countries. We conclude that rather than searching for a single unifying framework for gender and resilience analysis, it will be more effective to pursue a plural solution in which closer engagement is fostered between analysis of gender and social-ecological resilience whilst preserving the strengths of each approach. This approach can make an important contribution to developing a better evidence base for small-scale fisheries management and policy