Impact of energy supply infrastructure in life cycle analysis of hydrogen and electric systems applied to the Portuguese transportation sector

Hydrogen and electric vehicle technologies are being considered as possible solutions to mitigate environmental burdens and fossil fuel dependency. Life cycle analysis (LCA) of energy use and emissions has been used with alternative vehicle technologies to assess the Well-to-Wheel (WTW) fuel cycle or the Cradle-to-Grave (CTG) cycle of a vehicle's materials. Fuel infrastructures, however, have thus far been neglected. This study presents an approach to evaluate energy use and CO₂ emissions associated with the construction, maintenance and decommissioning of energy supply infrastructures using the Portuguese transportation system as a case study. Five light-duty vehicle technologies are considered: conventional gasoline and diesel (ICE), pure electric (EV), fuel cell hybrid (FCHEV) and fuel cell plug-in hybrid (FC-PHEV). With regard to hydrogen supply, two pathways are analysed: centralised steam methane reforming (SMR) and on-site electrolysis conversion. Fast, normal and home options are considered for electric chargers. We conclude that energy supply infrastructures for FC vehicles are the most intensive with 0.03–0.53 MJ_eq/MJ emitting 0.7–27.3 g CO_2eq/MJ of final fuel. While fossil fuel infrastructures may be considered negligible (presenting values below 2.5%), alternative technologies are not negligible when their overall LCA contribution is considered. EV and FCHEV using electrolysis report the highest infrastructure impact from emissions with approximately 8.4% and 8.3%, respectively. Overall contributions including uncertainty do not go beyond 12%.     

Energy demand and emissions from road transportation vehicles in China

Rapidly growing energy demand and emissions from China's road transportation vehicles in the last two decades have raised concerns over oil security, urban air pollution and global warming. This rapid growth will be likely to continue in the next two to three decades as the vehicle ownership level in China is still very low. The current status of China's road transport sector in terms of vehicles, infrastructure, energy use and emissions is presented. Mitigation measures implemented and those that can reasonably be expected to be adopted in the near future are analysed. Recent studies exploring the future trends of road vehicle energy demand and emissions under various strategies are reviewed. Moreover, those studies which assessed various fuel/propulsion options in China from a life cycle perspective are examined to present an overview of the potential for reducing energy use and emissions. Recommendations for further developments are also made. It is concluded that comprehensive and appropriate strategies will be needed to minimise the adverse impacts of China's road vehicles on energy resources and the environment. Fortunately, China appears to be heading in this direction.     

Eco-efficiency of H2 and fuel cell buses

Urban governments are continually striving to improve air quality by making public transportation more environmentally friendly. H₂ fuel cell buses (FCBs) offer one of the best ways to reduce air pollution. FCB has high energy efficiency and lower air pollutant emissions than conventional buses (e.g. diesel bus/Compressed natural gas bus, CNGB), and H₂ is an attractive alternative energy source in the face of depleting fossil fuels and global warming. H₂ can be produced via fossil fuels and renewable sources and then stored and distributed in a variety of different ways. While many contend that H₂ and FCB are not yet commercially viable, H₂ technology has developed a great deal over recent years. This fact alone demands that governments as well as for-profit businesses take a discerning look at what H₂ and FCB have to offer in terms of both environmental and economic opportunities.In this study, environmental and economic aspects of hydrogen pathways are analyzed according to plausible production methods and capacity, and distribution options in Korea using life cycle assessment (LCA) and life cycle costing (LCC) methods. This study considers the following means of hydrogen production: naphtha steam reforming (Naphtha SR), natural gas steam reforming (NG SR), and water electrolysis (WE). Additionally, conventional fuels (Diesel and CNG) are also included as target fuel pathways in order to identify which hydrogen pathway in particular has the greatest environmental advantage over conventional fuels. This study aimed to identify whether H₂ and FCB can compete with conventional fuels used in buses in terms of the eco-efficiency method, which focuses on economic feasibility and environmental improvement.The conclusion of this study is that H₂ pathways, especially, Naphtha SR [C] and NG SR [S], are more competitive than conventional fuels from an eco-efficiency perspective. As a result, switching from conventional transportation fuel to these suggested H₂ pathways is expected to offer an economically and environmentally more eco-efficient means of transportation. Henceforth, drawing upon evidence within this report, decision-makers would be wise to invest in more cost-effective and environment-friendly fuels by constructing an optimal H₂ infrastructure.     

Energy use, cost and CO2 emissions of electric cars

We examine efficiency, costs and greenhouse gas emissions of current and future electric cars (EV), including the impact from charging EV on electricity demand and infrastructure for generation and distribution.Uncoordinated charging would increase national peak load by 7% at 30% penetration rate of EV and household peak load by 54%, which may exceed the capacity of existing electricity distribution infrastructure. At 30% penetration of EV, off-peak charging would result in a 20% higher, more stable base load and no additional peak load at the national level and up to 7% higher peak load at the household level. Therefore, if off-peak charging is successfully introduced, electric driving need not require additional generation capacity, even in case of 100% switch to electric vehicles.GHG emissions from electric driving depend most on the fuel type (coal or natural gas) used in the generation of electricity for charging, and range between 0 g km⁻¹ (using renewables) and 155 g km⁻¹ (using electricity from an old coal-based plant). Based on the generation capacity projected for the Netherlands in 2015, electricity for EV charging would largely be generated using natural gas, emitting 35-77 g CO_2 eq km⁻¹.We find that total cost of ownership (TCO) of current EV are uncompetitive with regular cars and series hybrid cars by more than 800 € year⁻¹. TCO of future wheel motor PHEV may become competitive when batteries cost 400 € kWh⁻¹, even without tax incentives, as long as one battery pack can last for the lifespan of the vehicle. However, TCO of future battery powered cars is at least 25% higher than of series hybrid or regular cars. This cost gap remains unless cost of batteries drops to 150 € kWh⁻¹ in the future. Variations in driving cost from charging patterns have negligible influence on TCO.GHG abatement costs using plug-in hybrid cars are currently 400-1400 € tonne⁻¹ CO_2 eq and may come down to −100 to 300 € tonne⁻¹. Abatement cost using battery powered cars are currently above 1900 € tonne⁻¹ and are not projected to drop below 300-800 € tonne⁻¹.     

Energy consumption and CO2 emissions of the European glass industry

An in-depth analysis of the energy consumption and CO₂ emissions of the European glass industry is presented. The analysis is based on data of the EU ETS for the period 2005–2007 (Phase I). The scope of this study comprises the European glass industry as a whole and its seven subsectors. The analysis is based on an assignment of the glass installations (ca. 450) within the EU ETS to the corresponding subsectors and an adequate matching of the respective production volumes. A result is the assessment of the overall final energy consumption (fuel, electricity) as well as the overall CO₂ emissions (process, combustion and indirect emissions) of the glass industry and its subsectors in the EU25/27. Moreover, figures on fuel mix as well as fuel intensity and CO₂ emissions intensity (i.e. carbon intensity) are presented for each of the subsectors on aggregated levels and for selected EU Member States separately. The average intensity of fuel consumption and direct CO₂ emissions of the EU25 glass industry decreased from 2005 to 2007 by about 4% and amounted in 2007 to 7.8 GJ and 0.57 _tCO₂${\mathrm{t}}_{{\text{CO}}_{\mathrm{2}}}$ per tonne of saleable product, respectively. The economic energy intensity was evaluated with 0.46 toe/1000€ (EU27).     

Selection of CO2 chemisorbent for fuel-cell grade H2 production by sorption-enhanced water gas shift reaction

New experimental data are reported to demonstrate that high purity H₂ can be directly produced by sorption-enhanced water gas shift (WGS) reaction using synthesis gas (CO + H₂O) as sorber-reactor feed gas. An admixture of a commercial WGS catalyst and a proprietary CO₂ chemisorbent (K₂CO₃ promoted hydrotalcite or Na₂O promoted alumina) was used in the sorber-reactor for removal of CO₂, the WGS reaction by-product, from the reaction zone. The promoted alumina was found to be a superior CO₂ chemisorbent for this application because (a) it could directly produce a fuel-cell grade H₂ product (<10–20 ppm CO) at reaction temperatures of 200 and 400 °C, and (b) it produced ∼45.6% more high purity H₂ product per unit amount of sorbent than the promoted hydrotalcite at 400 °C. Furthermore, the specific fuel-cell grade H₂ productivity by the promoted alumina at a reaction temperature of 200 °C was ∼3.6 times larger than that at 400 °C. These striking differences in the performance of the two CO₂ chemisorbents were caused by the differences in their CO₂ sorption equilibria and kinetics.     

CO2 emissions,electricity consumption and output in ASEAN

This study examines the causal relationship between carbon dioxide emissions, electricity consumption and economic growth within a panel vector error correction model for five ASEAN countries over the period 1980–2006. The long-run estimates indicate that there is a statistically significant positive association between electricity consumption and emissions and a non-linear relationship between emissions and real output, consistent with the environmental Kuznets curve. The long-run estimates, however, do not indicate the direction of causality between the variables. The results from the Granger causality tests suggest that in the long-run there is unidirectional Granger causality running from electricity consumption and emissions to economic growth. The results also point to unidirectional Granger causality running from emissions to electricity consumption in the short-run.     

CO2 emissions,energy consumption,and output in France

This paper examines the dynamic causal relationships between pollutant emissions, energy consumption, and output for France using cointegration and vector error-correction modelling techniques. We argue that these variables are strongly inter-related and therefore their relationship must be examined using an integrated framework. The results provide evidence for the existence of a fairly robust long-run relationship between these variables for the period 1960–2000. The causality results support the argument that economic growth exerts a causal influence on growth of energy use and growth of pollution in the long run. The results also point to a uni-directional causality running from growth of energy use to output growth in the short run.     

Hydrogen permeation through a Pd-based membrane and RWGS conversion in H2/CO2, H2/N2/CO2 and H2/H2O/CO2 mixtures

This study investigated the effect of gases such as CO₂, N₂, H₂O on hydrogen permeation through a Pd-based membrane −0.012 m² – in a bench-scale reactor. Different mixtures were chosen of H₂/CO₂, H₂/N₂/CO₂ and H₂/H₂O/CO₂ at temperatures of 593–723 K and a hydrogen partial pressure of 150 kPa. Operating conditions were determined to minimize H₂ loss due to the reverse water gas shift (RWGS) reaction. It was found that the feed flow rate had an important effect on hydrogen recovery (HR). Furthermore, an identification of the inhibition factors to permeability was determined. Additionally, under the selected conditions, the maximum hydrogen permeation was determined in pure H₂ and the H₂/CO₂ mixtures. The best operating conditions to separate hydrogen from the mixtures were identified.     

Steam cracking and methane to olefins: Energy use,CO2 emissions and production costs

While most olefins (e.g., ethylene and propylene) are currently produced through steam cracking routes, they can also possibly be produced from natural gas (i.e., methane) via methanol and oxidative coupling routes. We reviewed recent data in the literature and then compared the energy use, CO₂ emissions and production costs of methane-based routes with those of steam cracking routes. We found that methane-based routes use more than twice as much process energy than state-of-the-art steam cracking routes do (the energy content of products is excluded). The methane-based routes can be economically attractive in remote, gas-rich regions where natural gas is available at low prices. The development of liquefied natural gas (LNG) may increase the prices of natural gas in these locations. Oxidative coupling routes are currently still immature due to low ethylene yields and other problems. While several possibilities for energy efficiency improvement do exist, none of the natural gas-based routes is likely to become more energy efficient or to lead to less CO₂ emissions than steam cracking routes do.     

Performance of Na2O promoted alumina as CO2 chemisorbent in sorption-enhanced reaction process for simultaneous production of fuel-cell grade H2 and compressed CO2 from synthesis gas

The performance of a novel thermal swing sorption-enhanced reaction (TSSER) concept for simultaneous production of fuel-cell grade hydrogen and compressed carbon dioxide as a by-product from a synthesis gas feed is simulated using Na₂O promoted alumina as a CO₂ chemisorbent in the process. The process simultaneously carries out the water gas shift (WGS) reaction and removal of CO₂ from the reaction zone by chemisorption in a single unit. Periodic regeneration of the chemisorbent is achieved by using the principles of thermal swing adsorption employing super-heated steam purge.     

Electric and plug-in hybrid vehicles influence on CO2 and water vapour emissions

The main objective of this research is to quantify the impact of introducing electric vehicles and plug-in hybrid vehicles, including fuel cell on conventional fleets. The impact is estimated in terms of local pollutants, HC, CO, NO_x, PM, and in terms of CO₂ and water vapour global emissions. The specific fleet of Portugal, roughly 6 million light-duty vehicles (30% diesel, 70% gasoline) is considered, and the mobility indicator of the fleet, 90 thousand million p × km, is kept constant throughout the analysis. Probability density functions for energy consumption and emissions are derived for conventional, electric and plug-in hybrid vehicles, in charge depleting and charge sustaining modes. The Monte Carlo method is used to obtain average distribution estimates for discounting values of “old vehicles” that are removed from the fleet, and to add average distribution estimates for the “new vehicles” entering the fleet. Considering the actual Portuguese fleet as the reference case, local pollutant emissions decrease by a factor of 10-53%, for 50% fleet replacement. A potential 23% decrease of CO₂ is foreseen, and a potential 31% increase of H₂O emissions is forecasted. Life cycle water vapour emissions tend to rise and are, typically, 2-4 times higher than CO₂ values at the upstream stage, due to its release in the cooling towers of thermal power plants. It is interesting to note that considering 1 MJ of energy required at vehicle wheels, in an overall life cycle context, both fuel cell and electric modes have nearly twice as much H₂O emissions than internal combustion vehicles. CO₂ emissions tend to decrease with electric drive vehicles penetration due to the higher fleet life cycle efficiency.     

CO2 emissions,energy consumption and economic growth in BRIC countries

This paper examines dynamic causal relationships between pollutant emissions, energy consumption and output for a panel of BRIC countries over the period 1971–2005, except for Russia (1990–2005). In long-run equilibrium energy consumption has a positive and statistically significant impact on emissions, while real output exhibits the inverted U-shape pattern associated with the Environmental Kuznets Curve (EKC) hypothesis with the threshold income of 5.393 (in logarithms). In the short term, changes in emissions are driven mostly by the error correction term and short term energy consumption shocks, as opposed to short term output shocks for each country. Short-term deviations from the long term equilibrium take from 0.770 years (Russia) to 5.848 years (Brazil) to correct. The panel causality results indicate there are energy consumption–emissions bidirectional strong causality and energy consumption–output bidirectional long-run causality, along with unidirectional both strong and short-run causalities from emissions and energy consumption, respectively, to output. Overall, in order to reduce emissions and not to adversely affect economic growth, increasing both energy supply investment and energy efficiency, and stepping up energy conservation policies to reduce unnecessary wastage of energy can be initiated for energy-dependent BRIC countries.     

Life-cycle greenhouse gas emissions and energy balances of sugarcane ethanol production in Mexico

The purpose of this work was to estimate GHG emissions and energy balances for the future expansion of sugarcane ethanol fuel production in Mexico with one current and four possible future modalities. We used the life cycle methodology that is recommended by the European Renewable Energy Directive (RED), which distinguished the following five system phases: direct Land Use Change (LUC); crop production; biomass transport to industry; industrial processing; and ethanol transport to admixture plants. Key variables affecting total GHG emissions and fossil energy used in ethanol production were LUC emissions, crop fertilization rates, the proportion of sugarcane areas that are burned to facilitate harvest, fossil fuels used in the industrial phase, and the method for allocation of emissions to co-products. The lower emissions and higher energy ratios that were observed in the present Brazilian case were mainly due to the lesser amount of fertilizers applied, also were due to the shorter distance of sugarcane transport, and to the smaller proportion of sugarcane areas that were burned to facilitate manual harvest. The resulting modality with the lowest emissions of equivalent carbon dioxide (CO_2e) was ethanol produced from direct juice and generating surplus electricity with 36.8 kgCO_2e/GJ_ethanol. This was achieved using bagasse as the only fuel source to satisfy industrial phase needs for electricity and steam. Mexican emissions were higher than those calculated for Brazil (27.5 kgCO_2e/GJ_ethanol) among all modalities. The Mexican modality with the highest ratio of renewable/fossil energy was also ethanol from sugarcane juice generating surplus electricity with 4.8 GJ_ethanol/GJ_fossil.     

Blending blue hydrogen with natural gas for direct consumption: Examining the effect of hydrogen concentration on transportation and well-to-combustion greenhouse gas emissions

Jurisdictions are looking into mixing hydrogen into the natural gas (NG) system to reduce greenhouse gas (GHG) emissions. Earlier studies have focused on well-to-wheel analysis of H₂ fuel cell vehicles, using high-level estimates for transportation-based emissions. There is limited research on transportation emissions of hythane, a blend of H₂ and NG used for combustion. An in-depth analysis of the pipeline transportation system was performed for hythane and includes sensitivity and uncertainty analyses. When hythane with 15% H₂ is used, transportation GHG emissions (gCO2eq/GJ) increase by 8%, combustion GHG emissions (gCO2eq/GJ) decrease by 5%, and pipeline energy capacity (GJ/hr) decreases by 11% for 50–100 million m³/d pipelines. Well-to-combustion (WTC) emissions increase by 2.0% without CCS, stay the same with a 41% CCS rate, decrease by 2.8% for the 100% CCS scenario, and decrease by 3.6% in the optimal CO₂-free scenario. While hythane contains 15% H₂ by volume only 5% of the gas’ energy comes from H₂, limiting its GHG benefit.     

Economic growth, CO2 emissions, and fossil fuels consumption in Iran

Environmental issues have attracted renewed interest and more attention during recent years due to climatic problems associated with the increased levels of pollution and the deterioration of the environmental quality as a result of increased human activity. This paper investigates the causal relationships between economic growth, carbon emission, and fossil fuels consumption, using the relatively new time series technique known as the Toda-Yamamoto method for Iran during the period 1967–2007. Total fossil fuels, petroleum products, and natural gas consumption are used as three proxies for energy consumption. Empirical results suggest a unidirectional Granger causality running from GDP and two proxies of energy consumption (petroleum products and natural gas consumption) to carbon emissions, and no Granger causality running from total fossil fuels consumption to carbon emissions in the long run. The results also show that carbon emissions, petroleum products, and total fossil fuels consumption do not lead to economic growth, though gas consumption does.     

Energy demand and CO2 emissions reduction options in Nigeria

This paper presents policy options for reducing CO₂ emissions in Nigeria. The policies were formulated based on a thorough analysis of Nigeria's current energy consumption patterns and the projected evolution of key parameters that drive Nigeria's energy demand — primarily the rate of industrialization, the demand for transportation services, and the expansion of Nigeria's population. The study shows that the most promising options for reducing CO₂ emissions in Nigeria are improving energy efficiency and increasing the use of natural gas and renewable energy sources.     

Incorporating life cycle assessments into building project decision-making: An energy consumption and CO2 emission perspective

In the past two decades, the globalization of financial markets and multinational trade has intensified internationally, and become increasingly competitive. In the construction industry, critical changes are initiated to reduce operating costs for achieving sustainable operation. Conventional cost pricing for building projects no longer apply as energy shortage and environmental pollution are new challenges faced by construction companies. Many countries have attempted to solve the CO₂ emission problems by levying a carbon tax, which leads to a higher cost for construction companies. Therefore, this study aims to adopt life cycle assessment (LCA) in order to assess CO₂ emission costs and apply a mathematical programming approach to allocate limited resources to maximize profits for construction companies.     

The cost of pipelining climate change mitigation: An overview of the economics of CH4, CO2 and H2 transportation

Gases like CH₄, CO₂ and H₂ may play a key role in establishing a sustainable energy system: CH₄ is the least carbon-intensive fossil energy resource; CO₂ capture and storage can significantly reduce the climate footprint of especially fossil-based electricity generation; and the use of H₂ as energy carrier could enable carbon-free automotive transportation. Yet the construction of large pipeline infrastructures usually constitutes a major and time-consuming undertaking, because of safety and environmental issues, legal and (geo)political siting arguments, technically un-trivial installation processes, and/or high investment cost requirements. In this article we focus on the latter and present an overview of both the total costs and cost components of the distribution of these three gases via pipelines. Possible intricacies and external factors that strongly influence these costs, like the choice of location and terrain, are also included in our analysis. Our distribution cost breakdown estimates are based on transportation data for CH₄, which we adjust for CO₂ and H₂ in order to account for the specific additional characteristics of these two gases. The overall trend is that pipeline construction is no longer subject to significant cost reductions. For the purpose of designing energy and climate policy we therefore know in principle with reasonable certainty what the minimum distribution cost components of future energy systems are that rely on pipelining these gases. We describe the reasons why we observe limited learning-by-doing and explain why negligible construction cost reductions for future CH₄, CO₂ and H₂ pipeline projects can be expected. Cost data of individual pipeline projects may strongly deviate from the global average because of national or regional effects related to the type of terrain, but also to varying costs of labor and fluctuating market prices of components like steel.