Lignocellulosic Ethanol: The Path to Market

The cost effective production of transport fuels from biomass is essential if the EU aspiration to substitute 10% of transport fuels with sustainable alternatives by 2020 is to be met. The hope, voiced by the Parliament’s Industry and Energy Committee, is that at least 40% of the 2020 target will come from second-generation biofuels, and therein lies the challenge: second-generation conversion technologies are not yet commercial. Multiple pathways are being investigated around the globe, but dominant pathways have yet to emerge and business models have yet to be proven. Nevertheless, expectations are running high and there has been significant investment in R&D in the US, Europe and Asia. The production of ethanol from lignocellulosic biomass is commercially and environmentally one of the most promising options, and in 2007 the US Department of Energy (DOE) provided more than US$1 billion toward lignocellulosic ethanol (LE) projects. Their goal was to make the fuel cost competitive at$1.33 per gallon, when deployed at scale, by 2012. The majority of studies also suggest that LE will result in superior greenhouse gas savings compared to ethanol produced from starch. Despite favourable predictions for cost and environmental performance, market deployment requires practical and plausible development paths that are able to support progress from existing small-scale demonstration plant to large industrial installations. Moreover, these development paths must be sufficiently attractive to persuade developers and investors that lignocellulosic ethanol remains an opportunity worth pursuing

Prioritising the best use of biomass resources: conceptualising trade-offs

02.09.13 KB. Ok to add report to Spiral. Authors hold copyrightUsing biomass to provide energy services is one of the most versatile options for increasing the proportion of renewable energy in the existing system. This report reviews metrics used to compare alternative bio-energy pathways and identifies limitations inherent in the way that they are calculated and interpreted. It also looks at how companies and investors approach strategic decisions in the bio-energy area. Bio-energy pathways have has physical and economic attributes that can be measured or modelled. These include: the capital cost, operating cost, emissions to air, land and water. Conceptually, comparing alternative pathways is as simple as selecting the attributes and metrics you consider to be most important and ranking the alternative pathways accordingly. At an abstract level there is good agreement about which features of bio-energy pathways are desirable, but there is little agreement about which performance metrics best capture all the relevant information about a bio-energy pathway. Between studies there is also a great deal of variation and this impedes comparison. Common metrics describe energetic performance, economic performance, environmental performance (emissions, land and water use), and social and ecological performance. Compound metrics may be used to integrate multiple attributes but their highly aggregate nature may make them difficult to interpret. Insights that may be drawn from the analysis include:

Solutions to the reconstruction problem in asymptotic safety

Starting from a full renormalised trajectory for the effective average action (a.k.a. infrared cutoff Legendre effective action) $\Gamma_k$, we explicitly reconstruct corresponding bare actions, formulated in one of two ways. The first step is to construct the corresponding Wilsonian effective action $S^k$ through a tree-level expansion in terms of the vertices provided by $\Gamma_k$. It forms a perfect bare action giving the same renormalised trajectory. A bare action with some ultraviolet cutoff scale $\Lambda$ and infrared cutoff $k$ necessarily produces an effective average action $\Gamma^\Lambda_k$ that depends on both cutoffs, but if the already computed $S^\Lambda$ is used, we show how $\Gamma^\Lambda_k$ can also be computed from $\Gamma_k$ by a tree-level expansion, and that $\Gamma^\Lambda_k\to\Gamma_k$ as $\Lambda\to\infty$. Along the way we show that Legendre effective actions with different UV cutoff profiles, but which correspond to the same Wilsonian effective action, are related through tree-level expansions. All these expansions follow from Legendre transform relationships that can be derived from the original one between $\Gamma^\Lambda_k$ and $S^k$.Comment: 32 page

The UK bio-energy resource base to 2050: estimates, assumptions, and uncertainties

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Global bioenergy resources

Using biomass to provide energy services is a strategically important option for increasing the global uptake of renewable energy. Yet the practicalities of accelerating deployment are mired in controversy over the potential resource conflicts that might occur, particularly over land, water and biodiversity conservation. This calls into question whether policies to promote bioenergy are justified. Here we examine the assumptions on which global bioenergy resource estimates are predicated. We find that there is a disjunct between the evidence that global bioenergy studies can provide and policymakers' desire for estimates that can straightforwardly guide policy targets. We highlight the need for bottom-up assessments informed by empirical studies, experimentation and cross-disciplinary learning to better inform the policy debate

Planetary benchmarks

Design criteria and technology requirements for a system of radar reference devices to be fixed to the surfaces of the inner planets are discussed. Offshoot applications include the use of radar corner reflectors as landing beacons on the planetary surfaces and some deep space applications that may yield a greatly enhanced knowledge of the gravitational and electromagnetic structure of the solar system. Passive retroreflectors with dimensions of about 4 meters and weighing about 10 kg are feasible for use with orbiting radar at Venus and Mars. Earth-based observation of passive reflectors, however, would require very large and complex structures to be delivered to the surfaces. For Earth-based measurements, surface transponders offer a distinct advantage in accuracy over passive reflectors. A conceptual design for a high temperature transponder is presented. The design appears feasible for the Venus surface using existing electronics and power components