LCA of the timber sector in Ghana: preliminary life cycle impact assessment (LCIA)

Purpose - Most life cycle impact assessment (LCIA) approaches in life cycle assessment (LCA) are developed for western countries. Their LCIA approaches and characterization methodologies for different impact categories may not be necessarily relevant to African environmental conditions and particularly not for the timber sector in Ghana. This study reviews the relevance of existing impact categories and LCIA approaches, and uses the most relevant for the timber sector of Ghana. Materials and methods - The study reviewed 23 life cycle inventories (LCIs) and LCAs on forestry, timber, and wood products for relevant impact categories and LCIA approaches for their relevance to the specific conditions in Ghana. This study uses an earlier LCI study of the timber industry as a starting point for an additional LCIA. We next performed a correlation and regression analysis to learn whether wood wastes may function as a reasonable single indicator for land use as proxy for biodiversity loss and the other impact categories. Results and discussion - The literature review shows that no LCI or LCA studies were developed for Africa or the tropics. The LCIA approaches in the reviewed LCAs are indeed shown to take their basis in the environmental problems in western countries and characterization methodologies relating to how these problems manifest themselves in the western world. Characterization methodologies for different impact categories in CML-2000 and other LCIA approaches may not be necessarily relevant to African tropical environmental conditions and particularly not for the timber sector in Ghana. This situation hampers the reliability of our LCIA and points to a serious research gap in LCIA development in general. We applied the scientifically well-recognized CML 2000 to the earlier LCI results and characterized the preliminary selected impact categories of global warming, acidification, eutrophication, photochemical oxidant formation, and human toxicity. The correlation analysis indicated that wood waste is indeed strongly correlated with land use as proxy for biodiversity loss and also positively correlated with the other five potential impact results. It can be concluded that wood waste production is a major driving force for biodiversity loss and a sufficiently good single indicator for all other environmental performance indicators in the timber sector of Ghana. Conclusions - This study and the previous LCI paper are pioneering a field not yet explored, since the correct environmental performance indicators are not yet developed or adapted to tropical conditions. The development of LCIA approaches in the tropics may be the start of a never-ending journey in LCA research in Africa, particularly Ghana

Inventory analysis of the timber industry in Ghana

Background, aim, and scope The timber sector, i.e., forestry and timber industry, plays an important role in the socioeconomic development of Ghana through timber products export. Timber production in this sector is associated with increasing environmental burdens in terms of use of materials and energy, production of emissions and waste, and land use changes. The purpose of this study was to compile a comprehensive life cycle inventory (LCI) to identify the most dominant environmental pressures for five major production lines in the timber industry, and to evaluate the influence of the choice of the functional unit on the results (1 m3, 1 kg, and 1 euro). LCA’s of wood typically base their functional unit on volume, but mass or money may be more appropriate for the rather different products considered in this study. Materials and methods The LCI covers five timber production lines, namely, air-dried lumber, kiln-dried lumber, plywood, veneer, and furniture parts. Three functional units were used for this study to identify the most appropriate basis for a fair comparison of the different timber products (functional units were 1 m3, 1 kg and 1 euro). Questionnaires were administered to thirty selected companies in Ghana. These companies provided data about their material uses, energy requirements, and waste production for their operations from 2000 to 2007. The collected data were first converted into total annual average values, and next extrapolated to reflect the national average data for all 104 active companies. Finally, these data were expressed per functional unit for each of the five product lines on the basis of their production outputs (in volume, mass or money according to functional unit applied). Forest land used changes data was taken from the Ghana Timber Industry Development Division. Emissions for the several activities were taken from literature. Results and discussion Land use change for timber production in Ghana between the estimated periods turned out to be 34.0¿×¿103 ha per year, which will lead to complete deforestation in the year 2023 if continued. The total energy consumed by the timber sector per year was estimated at 1.9¿×¿109 MJ per year. The results showed that CO2 emissions by the timber sector activities per year accounted for 745k tons per year and dominate overall greenhouse gases emissions in the timber sector (changes in carbons storage related to land use changes not included). Wood waste by the timber sector accounted for 0.8 million m3 per year. The enormous wastage of wood contributes enormously to the rapid depletion of the country’s timber resources. The choice of the functional unit influences inventory results. The money-based functional unit, which also seems more appropriate for the different products considered, favors the value-added. Value-added products with strict sustainable forest management policy hold a promising future in terms of sustainability for the timber industry in Ghana. Conclusions This study has yielded good quality primary data unique for LCA research in Africa. This will enhance LCA approaches in Ghana, and allows here identification of the main environmental pressures and their dominantly contributing processes in the timber sector. Land use changes due to forestry form a critical issue and require urgent attention. The chosen functional units’ plays a crucial role in the environmental comparison of production line in the timber sector in Ghana. Recommendations and perspectives A comprehensive and transparent inventory for the timber industry provides the industry with an overview of areas in which material and thus economic savings can be made for the good of both environment and the industry finances. Good data keeping in the Ghanaian timber industry will help to build the required research capacity to develop local familiarity and competence in LCA techniques and applying these techniques will help to further certify tropical timber international markets

Gravity from spontaneous Lorentz violation

We investigate a class of theories involving a symmetric two-tensor field in Minkowski spacetime with a potential triggering spontaneous violation of Lorentz symmetry. The resulting massless Nambu-Goldstone modes are shown to obey the linearized Einstein equations in a fixed gauge. Imposing self-consistent coupling to the energy-momentum tensor constrains the potential for the Lorentz violation. The nonlinear theory generated from the self-consistent bootstrap is an alternative theory of gravity, containing kinetic and potential terms along with a matter coupling. At energies small compared to the Planck scale, the theory contains general relativity, with the Riemann-spacetime metric constructed as a combination of the two-tensor field and the Minkowski metric. At high energies, the structure of the theory is qualitatively different from general relativity. Observable effects can arise in suitable gravitational experiments

Massive photons and Lorentz violation

All quadratic translation- and gauge-invariant photon operators for Lorentz breakdown are included into the Stueckelberg Lagrangian for massive photons in a generalized \xi-gauge. The corresponding dispersion relation and tree-level propagator are determined exactly, and some leading-order results are derived. The question of how to include such Lorentz-violating effects into a perturbative quantum-field expansion is addressed. Applications of these results within Lorentz-breaking quantum field theories include the regularization of infrared divergences as well as the free propagation of massive vector bosons.Comment: 12 pages, 1 figur

Structural aspects of Lorentz-violating quantum field theory

In the last couple of decades the Standard Model Extension has emerged as a fruitful framework to analyze the empirical and theoretical extent of the validity of cornerstones of modern particle physics, namely, of Special Relativity and of the discrete symmetries C, P and T (or some combinations of these). The Standard Model Extension allows to contrast high-precision experimental tests with posited alterations representing minute Lorentz and/or CPT violations. To date no violation of these symmetry principles has been observed in experiments, mostly prompted by the Standard-Model Extension. From the latter, bounds on the extent of departures from Lorentz and CPT symmetries can be obtained with ever increasing accuracy. These analyses have been mostly focused on tree-level processes. In this presentation I would like to comment on structural aspects of perturbative Lorentz violating quantum field theory. I will show that some insight coming from radiative corrections demands a careful reassessment of perturbation theory. Specifically I will argue that both the standard renormalization procedure as well as the Lehmann-Symanzik-Zimmermann reduction formalism need to be adapted given that the asymptotic single-particle states can receive quantum corrections from Lorentz-violating operators that are not present in the original Lagrangian.Universidad Andres Bello DI-27-11/R DI-33-17/RG AAEC 2017/2 FONDECYT - 11121633info:eu-repo/semantics/publishedVersio

Sphaleron-Like Processes in a Realistic Heat Bath

We measure the diffusion rate of Chern-Simons number in the (1+1)-dimensional Abelian Higgs model interacting with a realistic heat bath for temperatures between 1/13 and 2/3 times the sphaleron energy. It is found that the measured rate is close to that predicted by the sphaleron approximation at the lower end of the temperature range considered but falls at least an order of magnitude short of the sphaleron estimate at the upper end of that range. We show numerically that the sphaleron approximation breaks down as soon as the gauge-invariant two-point function yields correlation length close to the sphaleron size.Comment: talk given at Lattice-93 conference (Dallas, October 1993), 3 pages, uuencoded postscript file, IPS Research Report 93-1

Cosmic-ray fermion decay by emission of on-shell W bosons with CPT violation

We study CPT and Lorentz violation in the electroweak gauge sector of the Standard Model in the context of the Standard-Model Extension. In particular, we consider the Lorentz-violating and CPT-odd Chern-Simons like parameter for the W boson, which is thus far unbounded by experiment. We demonstrate that any nonzero value of this parameter implies that, for sufficiently large energies, one of the polarization modes of the W boson propagates with spacelike four-momentum. In this scenario, an emission of W bosons by ultra-high-energy cosmic rays is possible. We calculate the induced fermion energy-loss rate, and we deduce the first limit on the pertinent Lorentz-and CPT-violating parameter that couples to the W boson. Consistency between the quantum description in various reference frames is preserved by using a recently formulated covariant quantization procedure for massive photons and applying it to the W bosons.Fundacao para a Ciencia e a Tecnologia of Portugal (FCT) (SFRH/BPD/101403/2014, POPH/FSE