Towards improved policy and institutional coherence in the promotion of sustainable biofuels in Mali

Interest in the promotion of biofuel investments to mediate the energy crisis and assist rural development is growing across sub-Saharan Africa. However, empirical evidence on how policy can effectively promote sustainable biofuels is largely lacking. This paper presents new, multi-level assessments of the implications of the Malian Strategy for Biofuels Development for the promotion of the oil-bearing, non-edible tree Jatropha curcas (Jatropha) as a sustainable development tool in Mali: a sub-Saharan African country that has led Jatropha-derived biofuel policy initiatives. In doing so, the paper addresses knowledge gaps on the role of national policy instruments in the uptake of biofuel activities. Semi-structured interviews were undertaken with government departments, international organizations, private sector representatives, non-governmental organizations and farming communities. Data show that mainstreaming internationally agreed principles into national policies is key to attract monetary, institutional and technical support from international organizations and donors. However, there are gaps between policy targets, actual yields and land cover. Jatropha oil supplies remain insufficient for improving access to fuel and substituting national consumption. Ambitious land cover targets set within national policies could risk land use shifts away from food towards biofuel production. Improved cooperation and coordination among state departments, enhanced monitoring of programmes and projects, as well as the establishment of adequate regulatory and fiscal frameworks governing private biofuel investments are needed to achieve sustainable outcomes

Acceleration Techniques for Discrete-Ordinates Transport Methods with Highly Forward-Peaked Scattering

In this dissertation, advanced numerical methods for highly forward peaked scattering deterministic calculations are devised, implemented, and assessed. Since electrons interact with the surrounding environment through Coulomb interactions, the scattering kernel is highly forward-peaked. This bears the consequence that, with standard preconditioning, the standard Legendre expansion of the scattering kernel requires too many terms for the discretized equation to be solved efficiently using a deterministic method. The Diffusion Synthetic Acceleration (DSA), usually used to speed up the calculation when the scattering is weakly anisotropic, is inefficient for electron transport. This led Morel and Manteuffel to develop a one-dimensional angular multigrid (ANMG) which has proved to be very effective when the scattering is highly anisotropic. Later, Pautz et al. generalized this scheme to multidimensional geometries, but this method had to be stabilized by a diffusive filter that degrades the overall convergence of the iterative scheme. In this dissertation, we recast the multidimensional angular multigrid method without the filter as a preconditioner for a Krylov solver. This new method is stable independently of the anisotropy of the scattering and is increasingly more effective and efficient as the anisotropy increases compared to DSA preconditioning wrapped inside a Krylov solver. At the coarsest level of ANMG, a DSA step is needed. In this research, we use the Modified Interior Penalty (MIP) DSA. This DSA was shown to be always stable on triangular cells with isotropic scattering. Because this DSA discretization leads to symmetric definite-positive matrices, it is usually solved using a conjugate gradient preconditioned (CG) by SSOR but here, we show that algebraic multigrid methods are vastly superior than more common CG preconditioners such as SSOR. Another important part of this dissertation is dedicated to transport equation and diffusion solves on arbitrary polygonal meshes. The advantages of polygonal cells are that the number of unknowns needed to mesh a domain can be decreased and that adaptive mesh refinement implementation is simplified: rather than handling hanging nodes, the adapted computational mesh includes different types of polygons. Numerical examples are presented for arbitrary quadrilateral and polygonal grids

ArborX: A Performance Portable Geometric Search Library

Searching for geometric objects that are close in space is a fundamental component of many applications. The performance of search algorithms comes to the forefront as the size of a problem increases both in terms of total object count as well as in the total number of search queries performed. Scientific applications requiring modern leadership-class supercomputers also pose an additional requirement of performance portability, i.e. being able to efficiently utilize a variety of hardware architectures. In this paper, we introduce a new open-source C++ search library, ArborX, which we have designed for modern supercomputing architectures. We examine scalable search algorithms with a focus on performance, including a highly efficient parallel bounding volume hierarchy implementation, and propose a flexible interface making it easy to integrate with existing applications. We demonstrate the performance portability of ArborX on multi-core CPUs and GPUs, and compare it to the state-of-the-art libraries such as Boost.Geometry.Index and nanoflann

Interaction of consumer preferences and climate policies in the global transition to low-carbon vehicles

Burgeoning demands for mobility and private vehicle ownership undermine global efforts to reduce energy-related greenhouse gas emissions. Advanced vehicles powered by low-carbon sources of electricity or hydrogen offer an alternative to conventional fossil-fuelled technologies. Yet, despite ambitious pledges and investments by governments and automakers, it is by no means clear that these vehicles will ultimately reach mass-market consumers. Here, we develop state-of-the-art representations of consumer preferences in multiple, global energy- economy models, specifically focusing on the non-financial preferences of individuals. We employ these enhanced model formulations to analyse the potential for a low-carbon vehicle revolution up to mid-century. Our analysis shows that a diverse set of measures targeting vehicle buyers is necessary for driving widespread adoption of clean technologies. Carbon pricing alone is insufficient for bringing low-carbon vehicles to mass market, though it can certainly play a supporting role in ensuring a decarbonised energy supply

Private household demand for vehicles on alternative fuels and drive trains: a review

ny attempt of the government to encourage the purchase of vehicles on alternative fuels and drive trains will depend on the acceptance of the end-users on the demand side. This paper offers an in-depth understanding of the consumers’ attitudes and preferences towards AFVs which can guide the government to establish effective policy measures. A comprehensive review of research is performed under different conceptual frameworks and research methodologies: attitudinal, experimental, preference valuation studies and others. Research findings are reported with the general objective to (1) uncover the attitudes and preferences towards AFVs and (2) examine whether the environmental benefits of AFVs play a role in the car purchase decision. Overall, there exists a strong environmental concern, and positive attitudes towards AFVs. However, environmental benefits are of little importance in the car purchase decision, which is principally driven by price characteristics, performance and convenience attributes. Limited knowledge levels also seem to prevent building up awareness of AFVs, which is the key to their adoption. The adoption of AFVs is likely to be limited without significant governmental incentives and regulations. Based on the key findings, it can be recommended that a combination of educational campaigns (e.g., information tools), pricing measures (e.g., differentiated vehicle taxation), supply-sided measures and large-scale demonstrations is required to support the adoption of AFVs. Document type: Articl

Evaluating cognitive and physical work performance: A comparative study of an active and passive industrial back-support exoskeleton

This work was supported by the European Union's Horizon 2020 research and innovation program SOPHIA under Grant Agreement No. 871237