Life cycle assessment of alternative energy types – including hydrogen – for public city buses in Taiwan

Human activities have exacerbated the global greenhouse effect, resulting in extreme climate changes that have caused disasters and food and water shortages in recent years. Transportation is one of the main causes of global greenhouse gas (GHG) emission. Therefore, policy makers must develop feasible strategies to reduce GHG emission. One of Taiwan's policy is to replace traditional diesel fuel urban buses with alternative energy buses. This paper uses a case study of city bus route No. 2 in Tainan City following the international standard ISO/TS 14067:2013 to measure the carbon footprint of different energy buses. The bus carbon footprints measured from high to low as: LNG buses, 63.14 g CO2e/pkm; traditional diesel buses, 54.6 g CO2e/pkm; liquefied petroleum gas (LPG) buses, 47.4 g CO2e/pkm; plug-in electric buses, 37.82 g CO2e/pkm, and hydrogen fuel cell buses, 29.17 g CO2e/pkm. If all urban area public buses in Taiwan were switched to hydrogen fuel cell buses, this would reduce CO2e footprint by 227,832.39 t annually. This reduction is equivalent to planting 22.78 million trees.     

Economic impact of performances degradation on the competitiveness of energy storage technologies – Part 2: Application on an example of PV production guarantee

In this paper, the newly developed techno-economic assessment platform Odyssey introduced in Part 1 of this two-part series of papers is applied to an application example: the call for tenders from the French Energy Regulation Commission on PV installations greater than 250 kWp. In this context, two storage systems are studied: a bank of lead-acid batteries and a PEM hydrogen chain (PEM electrolyzer, H₂/O₂ PEM fuel-cell, H₂ and O₂ storages under pressure at 30 bars). The objective pursued in the study of this application case is to assess the economic value of these two energy storage technologies and to focus on different influencing factors. Therefore, in the context of this application case, it is shown how a suitable control strategy can considerably help in improving economic results. The influence of the reference meteorological year is also investigated showing that the variations of economic indicators between two different years are greater than the variation of the annual insolation. Furthermore, the investigation on the influence of the simulation time step shows that the use of large time step (30 min, 1 h) may lead to unsuitable sizing and inaccurate estimations of economic performances. Finally systems sizing have been optimized considering different aging modeling which has shown that the influence of aging on the optimal sizing may be important.     

Substitutional V–Pd alloys for the membranes permeable to hydrogen: Hydrogen solubility at 150–400 °C

The development of non-palladium membrane for separation of hydrogen from gas mixtures is one of critical challenges of hydrogen energy. Vanadium based materials are most promising for such membranes. The alloying of pure vanadium is crucially important for reduction of hydrogen solubility to an optimal value. Solution of hydrogen in substitutional V-xPd alloys (x = 5, 7.3, 9.7, 12.3, 18.8 at%) was investigated. The pressure–composition-isotherms were obtained in the range of pressure (10–10⁶) Pa, temperature (150–400) °С and concentration of hydrogen, H/M, from 4·10⁻⁴ to 0.6. The alloying of vanadium with palladium was found to reduce the hydrogen solubility substantially greater than the alloying with other elements, e.g. by Ni and Cr. The hydrogen absorption in the V–Pd alloys obeyed Siverts' law including the range of undiluted solution with hydrogen concentration H/M > 0.1. The reduction in the hydrogen solubility due to the alloying of V with Pd was caused mainly by increase in the enthalpy of solution at nearly constant entropy factor. Changes in the gross electronic structure of metal are most probably responsible for the effects of alloying on the hydrogen solubility in the substitutional V–Pd alloys.     

Community support for campus approaches to sustainable energy use: The role of “town–gown” relationships

Across the United States, universities are grappling with challenges associated with adopting approaches to more sustainable energy use. One approach has been to develop energy-related projects in their local, host communities. Because host communities can play a major role in the successful planning and implementation of these projects, understanding the factors relating to their support is important. Building on research that suggests that procedural fairness is one such key factor, this study examines community members’ support of six approaches a local university could implement to work towards a goal of carbon neutrality. The results of a mail survey (N=677) found that perceived fairness of campus decision makers was significantly related to community support for the proposed approaches; however, beliefs about the efficacy of the different approaches to address challenges associated with climate change had the strongest relationship with support. The results also suggest that residents prefer changes in the energy infrastructure, such as the development of wind power, over the purchase of carbon offsets. We discuss the results in terms of actions that universities may take to foster community engagement in decision-making for university-sponsored sustainable energy projects.     

Why did China’s energy intensity increase during 1998–2006: Decomposition and policy analysis

Despite the fact that China’s energy intensity has continuously decreased during the 1980s and mostly 1990s, the decreasing trend has reversed since 1998 and the past few years have witnessed rapid increase in China’s energy intensity. We firstly conduct an index decomposition analysis to identify the key forces behind the increase. It is found that: (1) the high energy demand in industrial sectors is mainly attributed to expansion of production scale, especially in energy-intensive industries; (2) energy saving mainly comes from efficiency improvement, with energy-intensive sectors making the largest contribution; and (3) a heavier industrial structure also contributes to the increase. This study also makes the first attempt to bridge the quantitative decomposition analysis with qualitative policy analyses and fill the gap between decomposition results and policy relevance in previous work. We argue that: (1) energy efficiency improvement in energy-intensive sectors is mainly due to the industrial policies that have been implemented in the past few years; (2) low energy prices have directly contributed to high industrial energy consumption and indirectly to the heavy industrial structure. We provide policy suggestions in the end.     

Long-term energy consumptions of urban transportation: A prospective simulation of “transport–land uses” policies in Bangalore

The current trends of urban dynamics in the Third World are alarming with regard to climate change, because they are giving an increasingly important role to cars—to the detriment of public and non-motorized transportation. Yet this is the type of energy consumption that is expected to grow the fastest, in business-as-usual scenarios. How can these market-based urban trends be influenced? What level of emissions reduction can be achieved? This article shows that first, there is a relevant and urgent need to tackle the urban dynamics of cities in developing countries focusing on the “transport–land uses” couple, and second, that existing transport technologies and decision-helping tools are already available to take up the climate change challenge. Through the application of an integrated “transport–land uses” model, TRANUS, this study demonstrates that transit technologies affordable to an emerging city like Bangalore can significantly curb the trajectories of energy consumption and the ensuing carbon dioxide emissions, if and only if they are implemented in the framework of appropriate urban planning. Furthermore, this study establishes that there are tools which are available to facilitate the necessary policy-making processes. These tools allow stakeholders to discuss different political alternatives integrating energy issues, based on quantitative assessments.     

Combined effects of molar ratio and ball milling energy on the phase transformations and mechanical dehydrogenation in the lithium amide-magnesium hydride (LiNH2 + nMgH2)(n = 0.5–2.0) nanocomposites

The phase transformations occurring as a function of the ball milling energy injected into the hydride system (LiNH₂ + nMgH₂), having molar ratios n = 0.5–2.0, have been thoroughly studied. The milling energy in a magneto-mill is estimated by a semi-empirical method. X-ray diffraction (XRD) and Fourier Transform Infrared (FT-IR) measurements show that for the molar ratios n < 1.0 three new phases such as LiH, amorphous Mg(NH₂)₂ (a-Mg(NH₂)₂) and Li₂Mg(NH)₂ are formed during ball milling depending on the injected quantity of milling energy. Hydrogen is not released during milling when the LiH and a-Mg(NH₂)₂ hydrides are being formed whereas the formation of the Li₂Mg(NH)₂ hydride phase is always accompanied by a profound release of hydrogen. For the molar ratios n ≥ 1.0, at a low level of injected milling energy, the hydride phases formed are LiH and a-Mg(NH₂)₂. The latter reacts with MgH₂ during further milling to form the new phase MgNH whose formation is also accompanied by a profound release of hydrogen. Based on the experimental data we established an approximate hydride phase-injected milling energy diagram for various levels of injected milling energy and the molar ratios.     

Intermediate steps towards the 2000 W society in Switzerland: An energy–economic scenario analysis

In the future, sustainable development under the umbrella of the 2000 W society could be of major interest. Could the target of the 2000 W society, i.e. a primary energy per capita (PEC) consumption of 2000 W, be realized until 2050? Various combinations of PEC and CO₂ targets are tested, and the additional costs to be paid by the society are estimated. The assessment is carried out with the Swiss MARKAL model, a bottom-up energy-system model projecting future technology investments for Switzerland. The analysis reveals that the 2000 W society should be seen as a long-term goal. For all contemplated scenarios, a PEC consumption of 3500 W per capita (w/cap) is feasible in the year 2050. However, strong PEC consumption targets can reduce CO₂ emissions to an equivalent of 5% per decade at maximum. For stronger CO₂ emission reduction goals, corresponding targets must be formulated explicitly. At an oil price of 75 US$₂₀₀₀/bbl in 2050, the additional (cumulative, discounted) costs to reach a 10% CO₂ reduction per decade combined with a 3500 W per capita target amount to about 40 billion US$₂₀₀₀. On the contrary, to reach pure CO₂ reduction targets is drastically cheaper, challenging the vision of the 2000 W society.     

Hydrogen storage properties of 2 Mg–Fe mixtures processed by hot extrusion: Effect of ram speeds

Hot extrusion processing was used for producing bulk samples of 2MgFe mixtures adequate to hydrogen storage. High-energy ball milling was used to prepare 2MgFe powder mixtures, which were cold-pressed into cylindrical pre-forms. Such pre-forms were then processed by hot extrusion (at 300 °C and extrusion ratio of 3/1) to produce bulk samples. In this work, it was analyzed the influence of the ram speed (1, 5, and 10 mm/min) on the microstructure and hydrogen sorption properties of obtained bulks. Nanograins, which resulted from the milling process, remained in the nanosize after hot extrusion conditions. More porous samples were produced at a ram speed of 1 mm/min, which also kept the smaller grain size. These features led the sample processed at 1 mm/min to absorb about 4.8 wt% of H, which was higher than precursor powders that absorbed around 4.3 wt% of H. This behavior was assigned to a redistribution of Fe during extrusion, which was kept agglomerated in the powders. The results also showed that desorption temperatures of bulks were very similar to that of 2MgFe powders. Such behavior is very interesting, considering the lower surface area of bulks. When compared to MgH₂ powders, samples processed in this work presented much lower desorption temperatures. Except for the sample processed at 10 mm/min, all other samples fully desorbed in less than 8 min at 350 °C, while commercial MgH2 would take much more than 40 min for complete desorption.     

How important are current energy mix choices on future sustainability? Case study: Belgium and Spain—projections towards 2020–2030

Despite recent consumption decrease due to recession, European electricity sector is struggling to reach ambitious targets for reductions of greenhouse gas emissions. Our objective is to carry out a macro analysis of the energy mix in two European countries: Belgium and Spain. Life Cycle Assessments are carried for 2005 as well as for seven possible referenced scenarios to reach EU and also national legal objectives at the horizon 2020 and 2030. Ambitious renewable energy sources’ deployment plans can decrease impacts on the environment significantly as those sources replace polluting traditional sources, such as coal/lignite, oil or gas. When concentrating on projections for the future in Spain, results show that a mix with little coal and oil replaced by up to 54% of RES-E energy sources could bring environmental benefits with CO₂ emissions equivalent around 0.2 kg per kWh produced (compared with 0.54 kg in 2005). In Belgium, all future scenarios presented include more coal and gas with a limited share of RES-E; those mixes present more environmental harmful impacts (up to 0.56 kg CO₂ equivalent). This is why RES-E deployment is crucial as long as it is part of an electricity mix with reduced quantities of traditional fossil fuels.     

Microstructure and hydrogen desorption characteristics of hydrogenated ScH2–MBn (M = Mg and Ca) systems synthesized by mechanical milling

The mixtures of scandium hydride ScH₂ and metal boride MB_n, which is MgB₂ or CaB₆, were hydrogenated by mechanical milling under hydrogen pressure at room temperature. ScH₂–MgB₂ and ScH₂–CaB₆ desorbed 3.4 and 2.3 mass% of H₂, respectively, with peaks below 300 °C. The results of synchrotron radiation X-ray powder diffraction and X-ray absorption spectroscopy at the Sc K-edge indicated that ScB₂ was produced by milling. Fourier-transform infrared spectroscopy suggested that hydrogen was stored as B–H bonds in the as-milled samples. Nuclear magnetic resonance spectroscopy clarified the presence of metal borohydrides M(BH₄)₂ (M = Mg and Ca) in the as-milled ScH₂–MB_n mixtures. These results indicate that M(BH₄)₂ is synthesized by milling the ScH₂–MB_n mixtures under hydrogen pressure at room temperature, and hydrogen was desorbed from M(BH₄)₂. The by-products of M(BH₄)₂ are MgH₂ in the M = Mg case, which was observed by transmission electron microscopy, and ScB₂ in both cases.