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There is a widely believed myth that replacing the use of fossil fuels largely by renewable forms of energy is, with a possible exception of nuclear power, critically dependent on the development of appropriate new technologies. Accordingly, it is held that decarbonizing straight away is particularly difficult and expensive. There was a time when this idea had an element of reality, but this is no longer the case. Unfortunately, belief in this myth is shared by those in positions of influence. This paper serves to document that this presumed reality no longer holds, although the misconception may have been based on fact in the past. Whilst the survey of the available technology offered concentrates on electricity supply, it also documents that manufacture of synthetic fuels via hydrogen obtained by electrolysis of water and CO2 integrates smoothly with electricity grid stabilization as well as reducing the CO2 content of the atmosphere. The likely price and cost development in the energy market is also reviewed. In addition the role of CCS, in practice mainly capture from the air and industrial processes other than power generation is reviewed against the background of the cost effective generation of electricity by harvesting renewable forms of energy.

Abstract Bioenergy crops are one of the renewable energy options available to decarbonise the energy sector in Scotland and help to achieve the overall planned target of 80% reduction in greenhouse gas (GHG) emissions by 2050. A process-based model for poplar and willow developed for simulating the effect of different environmental and management options on growth and biomass yield was used to estimate the GHG abatement potential (GHG-AP) under different crop management options in Scotland. The model results of annual wood yield did not show a strong relation with any of the environmental factors except that of initial soil organic carbon (SOC) content. Increasing plant density and decreasing harvest frequency increased GHG-AP. Application of N-fertilizers at a rate of 50–100 kg N ha−1 resulted in the buildup of carbon in soils with less than 180 Mg C ha−1. However, in soils with greater SOC contents, annual emissions resulting from N fertilizer application were greater than the carbon saving through marginal increases in wood yield and SOC changes. The best management scenario in terms of economic and environmental objectives depends on identifying an optimum plant density based on the site specific conditions with a fertilizer application of 20–100 kg ha−1 y−1 and a five year harvest interval. Even under the best economic scenarios, SRC willow and poplar have a GHG-AP ranging from 9.9 to 11.6 and 8.8–10.0 Mg CO2 eq. ha−1 y−1, respectively. Under the best environmental scenarios this range increases to 10.5- 13.2 and 9–11.1 Mg CO2 eq. ha−1 y−1 for willow and poplar, respectively.

Abstract A process based life cycle assessment of dimension stone production in the UK has been carried out according to PAS 2050. From a survey of eight production operations, on a cradle-to-site basis for UK destinations the carbon footprint of sandstone is 77 kgCO2e/tonne, that of granite is 107 kgCO2e/tonne and that of slate is 251 kgCO2e/tonne. These values are considerably higher for stone imported from abroad due to the impact of transport. Reducing the reliance on imported stone will contribute to emissions reduction targets as well as furthering the goals of sustainable development.

Monthly-averaged 10-year climatological data series of global solar irradiation, average ambient temperature and mean relative humidity in Ibadan (lat. 7.43° N, long. 3.90° E), Nigeria, have been analysed using the Fourier series method. The pertinent amplitudes, phase angles, and harmonic angles have been obtained for each year of the series and for each variable. The study reveals that only the annual harmonic contributes in any significant way to explain the variance of the average temperature and the mean relative humitidy series, with percentages ranging between 57% and 91% for temperature and between 75% and 93% for the relative humidity. In the case of global solar irradiation, both the first and the second harmonics contribute almost equally to the total variance, with about 40% each. Typical annual time function parameters are provided for each of the three climatological variables.

AbstractVegetation growth is affected by past growth rates and climate variability. However, the impacts of vegetation growth carryover (VGC; biotic) and lagged climatic effects (LCE; abiotic) on tree stem radial growth may be decoupled from photosynthetic capacity, as higher photosynthesis does not always translate into greater growth. To assess the interaction of tree‐species level VGC and LCE with ecosystem‐scale photosynthetic processes, we utilized tree‐ring width (TRW) data for three tree species: Castanopsis eyrei (CE), Castanea henryi (CH, Chinese chinquapin), and Liquidambar formosana (LF, Chinese sweet gum), along with satellite‐based data on canopy greenness (EVI, enhanced vegetation index), leaf area index (LAI), and gross primary productivity (GPP). We used vector autoregressive models, impulse response functions, and forecast error variance decomposition to analyze the duration, intensity, and drivers of VGC and of LCE response to precipitation, temperature, and sunshine duration. The results showed that at the tree‐species level, VGC in TRW was strongest in the first year, with an average 77% reduction in response intensity by the fourth year. VGC and LCE exhibited species‐specific patterns; compared to CE and CH (diffuse‐porous species), LF (ring‐porous species) exhibited stronger VGC but weaker LCE. For photosynthetic capacity at the ecosystem scale (EVI, LAI, and GPP), VGC and LCE occurred within 96 days. Our study demonstrates that VGC effects play a dominant role in vegetation function and productivity, and that vegetation responses to previous growth states are decoupled from climatic variability. Additionally, we discovered the possibility for tree‐ring growth to be decoupled from canopy condition. Investigating VGC and LCE of multiple indicators of vegetation growth at multiple scales has the potential to improve the accuracy of terrestrial global change models.

Modern diesel engines are seeing increasing system and after-treatment complexity which can lead to significant increases in the exhaust back pressure (EBP). This increases the amount of trapped residuals, raising the charge temperature but reducing the oxygen concentration. In this work, these effects of the EBP on diesel engine performance and emissions under conventional and low-temperature diesel combustion (LTC) regimes were investigated. Increasing the EBP resulted in higher pumping work for both combustion modes. While for conventional diesel combustion the effect of the EBP on combustion and emissions were not significant, for LTC the higher back pressures influenced the combustion and emissions formation processes. At low-load conditions, the increase in the charge temperature advanced combustion; at intermediate-load conditions, the reduction in the oxygen concentration delayed it. Smoke emissions were significantly reduced by a higher back pressure at intermediate-load conditions.

The formation and development of dry bands can best be studied by modifying the standard test procedures. When such controlled behavior is allied with synchronized optical and electrical recordings, then characterization of the pre-formative leakage current, the transient phenomena associated with partial arcs across dry bands, the location of partial arcs and the voltage drop across dry bands can be determined. Interpretation of test data is greatly aided by finite element computation of insulating structures with a conducting surface layer. When this layer is continuous, this allows straightforward prediction of dry band formation under wetting conditions. Following formation, dry bands can be represented by discontinuities in this layer. Simulation of dry bands with various lengths, when combined with the test data, enables partial arc voltage gradients to be quantified. These results will be discussed in the context of previous work on the pollution flashover mechanism of ceramic insulators.

Abstract Standardization of biogas technology is immensely important for the promotion of the biogas industry worldwide. China has built a complete biogas standard system, which is divided into common, household biogas, biogas engineering, biogas digester for domestic sewage treatment, output utilization, and service system standards. The problems and potential barriers for biogas standardization in China are analyzed and come down to sluggish standard, overlapped standard, government-dominated standard, and lagging international standard. Accordingly, all potential biogas standards should be evaluated and placed under the same department. China Biogas Society and China Association of Rural Energy Industry play leading roles in developing enterprise or group/association biogas standards and ISO biogas standards. The bio-natural gas standard system and experimental standardization should be developed as well to replenish biogas standard system. A paradigm shift in biogas standardization should be from government-dominated to market-oriented model. The lessons learned for other developing countries includes expanding standardization to multi-aspects to realize full lifecycle control and management, building rapid responding mechanism of standardization to adopt industry transformation, integrating outdated standards into new versions, and establishing market-based standard system.

This paper presents a wind resource assessment in Venezuela using an efficient combination of spatial interpolation and orographic correction for wind mapping. Mesoscale modelling offers a relatively accurate means to model meteorological conditions by solving the continuity and momentum equations. However, this approach is both time and computationally demanding. The methodology used in this work offers a computationally inexpensive solution by combining both a simple geo-statistical Kriging method to interpolate horizontal wind speed and an orographic correction to account for changes on terrain elevation. Hourly observations of wind speed and direction for 34 masts recorded during the period 2005–2009 have been analysed in order to define a statistical model of wind resources. The resulting method, which includes an exploratory statistical analysis of the wind data, is a computationally economical alternative to mesoscale modelling. Simulations results include equivalent mean wind speeds and wind power maps which have been created to a height of 50, 80 and 120 m above the ground based on a horizontal resolution of 15×15 km. Results show that the greatest wind energy resources are located in the coastal area of Venezuela with a potential for offshore applications. Preliminary findings provide a very positive evidence for offshore exploitation of wind power. Results also suggest that wind energy resources for commercial use (utility-scale) are available in northern Venezuela, additionally; they suggest excellent conditions for wind power production for micro-scale applications, both on- and off-grid.