Life-cycle operational and embodied energy for a generic single-storey office building in the UK

Increasing energy efficiency makes embodied energy considerations increasingly significant. The energy initially embodied in a building could be as much as 67% of its operating energy over a 25-year period. If additional embodied energy gained over the building life is also included, the total life-cycle energy could be larger than the operating energy over the same period. Currently, embodied energy cannot be predicted accurately due to lack of reliable and accurate data; there is a wide variation in the data available. The variation of life-cycle operational and embodied energy and capital cost as a function of building parameters is explored.     

Partial slagging coal gasifier operational performance and product characteristics for energy sustainability in an integrated gasification combined cycle system

Operational performance of two ton/day coal partial slagging entrained-bed gasifier has been investigated. Coal to syngas conversion under operating temperature (1100–1300 °C), pressure (19.7–20.4 bar) and oxygen to coal ratio of 0.70 produced syngas at a flow rate of 177.5 Nm³/h. Composition of produced syngas was; CO 38–40 vol%, H₂ 22–23 vol%, CO₂ 7–8 vol%, and CH₄ 1.0–1.5 vol%. Carbon conversion and cold gas efficiency after one pass through operation were found to be 92.81% and 73.83% respectively. Fly ash fines produced were high in carbon content and acidic oxides than the bottom slag. Non-metal leaching nature of bottom slag was confirmed with ICP analysis. Based on the results, an industrial symbiosis can be established by recycling and reusing high carbon content fly ash fines in the gasifier. The same can be sold to other industries as a quality energy fuel. Slag produced can be used for the construction of roads and pavements.     

Assessing the environmental performance and sustainability of bioenergy production in Sweden: A life cycle assessment perspective

Bioenergy is one of the most dynamic and rapidly changing sectors of the global energy economy. The use of food crops for conversion to biofuel has been criticized for several reasons, among which its competition with the global food chain. Instead, lignocellulosic substrates are claimed to provide a bioenergy alternative without competing with food demand. This is particularly true when dealing with residues or waste. In this paper, we explored the environmental performance and sustainability of a bioenergy production system that integrates wastewater treatment, willow farming, and a Combined Heat and Power plant (CHP) located in Enköping (Sweden). Several methodologies for environmental assessment are integrated in this study within a life cycle perspective to investigate material and energy requirements as well as emissions and related impacts of the whole bioenergy production chain. Results show that full integration of different subsystems of a productive network is a desirable option for bioenergy production, within a zero emission oriented production pattern. The investigated wood biomass powered CHP plant was able to co-generate heat and electricity with high production efficiency and much better environmental performance and sustainability than fossil fuel based power plants.     

Gas fired combined cycle plant in Singapore: energy use,GWP and cost—a life cycle approach

A life cycle assessment was performed to quantify the non-renewable (fossil) energy use and global warming potential (GWP) in electricity generation from a typical gas fired combined cycle power plant in Singapore. The cost of electricity generation was estimated using a life cycle cost analysis (LCCA) tool. The life cycle assessment (LCA) of a 367.5 MW gas fired combined cycle power plant operating in Singapore revealed that hidden processes consume about 8% additional energy in addition to the fuel embedded energy, and the hidden GWP is about 18%. The natural gas consumed during the operational phase accounted for 82% of the life cycle cost of electricity generation. An empirical relation between plant efficiency and life cycle energy use and GWP in addition to a scenario for electricity cost with varying gas prices and plant efficiency have been established.     

地源热泵辐射供冷技术在展厅的应用

利用原有旧厂房改造为展示大厅,对其进行了节能改造及中央空调方案设计,对空调系统的运行情况进行了测试。测试结果表明,地源热泵辐射供冷中央空调系统有较好的制冷效果,室内人员工作区的温度保持在26～28℃,系统的性能系数为4.31,取得了显著的节能效果。     

Multi-objective design optimization of a natural gas-combined cycle with carbon dioxide capture in a life cycle perspective

The use of multi-objective optimization techniques is attractive to incorporate environmental objectives into the design of energy conversion systems. A method to locally optimize a given process while considering its global environmental impact by using life cycle assessment (LCA) to account for avoidable and unavoidable off-site emissions for each independent material input is presented. It is applied to study the integration of a CO₂-capture process using monoethanolamine in a natural gas-combined cycle power plant, simultaneously optimizing column dimensions, heat exchange, and absorbent flow configuration with respect to two objectives: the levelized cost of electricity and its life cycle global-warming potential. The model combines a process flow-sheeting model and a separate process-integration model. After optimization using an evolutionary algorithm, the results showed that widening the absorber and generating near-atmospheric pressure steam are cost-effective options but that increasing stripper complexity is less so. With $7.80/GJ natural gas and $20/ton CO₂ handling, the minimum on-site CO₂ abatement cost reaches $62.43/ton on a life cycle basis, achieved with a capture rate of over 90%. Of this, $2.13/ton is related to off-site emissions – a specific advantage of LCA that could help industries and governments anticipate the actual future costs of CO₂ capture.     

Modeling the life cycle energy and environmental performance of amorphous silicon BIPV roofing in the US

Building integrated photovoltaics (BIPV) perform traditional architectural functions of walls and roofs while also generating electricity. The displacement of utility generated electricity and conventional building materials can conserve fossil fuels and have environmental benefits. A life cycle inventory model is presented that characterizes the energy and environmental performance of BIPV systems relative to the conventional grid and displaced building materials. The model is applied to an amorphous silicon PV roofing shingle in different regions across the US. The electricity production efficiency (electricity output/total primary energy input excluding insolation) for a reference BIPV system (2kW_p PV shingle system with a 6% conversion efficiency and 20 year life) ranged from 3.6 in Portland OR to 5.9 in Phoenix, AZ indicating a significant return on energy investment. The reference system had the greatest air pollution prevention benefits in cities with conventional electricity generation mixes dominated by coal and natural gas, not necessarily in cities where the insolation and displaced conventional electricity were greatest.     

A benchmark for life cycle air emissions and life cycle impact assessment of hydrokinetic energy extraction using life cycle assessment

As the demand for renewable energy increases, it becomes important to critically examine the environmental impacts of renewable energy production. Often, the approach has been trial and error in renewable energy with respect to its impact on the environment. Hydrokinetic Energy Extraction (HEE) has been seen as a potentially “benign” form of renewable hydropower. This paper provides a benchmark for initial measurement of HEE environmental impacts, since negative outcomes have been present with previously assumed “benign” renewable hydropower. A Gorlov system was used to represent a HEE system. Life Cycle Assessment (LCA) was utilized to compare the environmental impacts of HEE with small hydropower, coal, natural gas and nuclear power. Environmental Protection Agency (EPA) criteria air emissions were quantified and compared over the life cycle of the systems. Life cycle air emissions were used in combination with TRACI to compare the systems. The Gorlov system was found to have the lowest life cycle impact with a system lifetime comparison, and did compare closely with small hydropower.     

Renewable energy technologies for the Indian power sector: mitigation potential and operational strategies

The future economic development trajectory for India is likely to result in rapid and accelerated growth in energy demand, with attendant shortages and problems. Due to the predominance of fossil fuels in the generation mix, there are large negative environmental externalities caused by electricity generation. The power sector alone has a 40 percent contribution to the total carbon emissions. In this context, it is imperative to develop and promote alternative energy sources that can lead to sustainability of the energy–environment system. There are opportunities for renewable energy technologies under the new climate change regime as they meet the two basic conditions to be eligible for assistance under UNFCCC mechanisms: they contribute to global sustainability through GHG mitigation; and, they conform to national priorities by leading to the development of local capacities and infrastructure. This increases the importance of electricity generation from renewables. Considerable experience and capabilities exist in the country on renewable electricity technologies. But a number of techno–economic, market-related, and institutional barriers impede technology development and penetration. Although at present the contribution of renewable electricity is small, the capabilities promise the flexibility for responding to emerging economic, socio–environmental and sustainable development needs. This paper discusses the renewable and carbon market linkages and assesses mitigation potential of power sector renewable energy technologies under global environmental intervention scenarios for GHG emissions reduction. An overall energy system framework is used for assessing the future role of renewable energy in the power sector under baseline and different mitigation scenarios over a time frame of 35 years, between 2000 to 2035. The methodology uses an integrated bottom-up modelling framework. Looking into past performance trends and likely future developments, analysis results are compared with officially set targets for renewable energy. The paper also assesses the CDM investment potential for power sector renewables. It outlines specific policy interventions for overcoming the barriers and enhancing deployment of renewables for the future.     

Development of a methodology for life cycle building energy ratings

Traditionally the majority of building energy use has been linked to its operation (heating, cooling, lighting, etc.), and much attention has been directed to reduce this energy use through technical innovation, regulatory control and assessed through a wide range of rating methods. However buildings generally employ an increasing amount of materials and systems to reduce the energy use in operation, and energy embodied in these can constitute an important part of the building's life cycle energy use. For buildings with ‘zero-energy’ use in operation the embodied energy is indeed the only life cycle energy use. This is not addressed by current building energy assessment and rating methods.     

Energy and the economy: an interrelated perspective

Energy consumption and economic activity for the United States has been closely related. Using input-output accounts, the variations between sectors which provide most of the consumer final demand are shown to be not as large as often assumed.The energy intensiveness of Continental Western European nations being only one half that of the United States, suggests that continued U.S. economic growth is possible without a corresponding increase in energy consumption. A reduction in energy intensiveness can be achieved through energy-related capital investments and social changes. Estimates for both the monetary value of the required capital investments and the corresponding energy required for the investments are obtained.     

Reduction of energy consumption in biodiesel fuel life cycle

Essential requirements for biofuel are that (a) it should be produced from renewable raw material, and (b) it should have a lower negative environmental impact than that of fossil fuels. Apart from direct assessment of the engine emissions, environmental impact is also determined by performing life cycle analysis. Life cycle energy balance depends on specific climatic conditions and the agro- and processing technologies used. Rapeseed oil methyl ester life cycle energy ratios in Lithuanian conditions have been calculated as a function of rapeseed productivity, oil pressing and transesterification technologies used.Opportunities to improve biodiesel fuel life cycle energy efficiency, by implementing new technologies in agriculture as well as in industrial processing, were reviewed. The effectiveness of new technologies was evaluated on the basis of energy balance comparison.     

Cooling strategies,summer comfort and energy performance of a rehabilitated passive standard office building

One of the first rehabilitated passive energy standard office buildings in Europe was extensively monitored over two years to analyse the cooling performance of a ground heat exchanger and mechanical night ventilation together with the summer comfort in the building. To increase the storage mass in the light weight top floor, phase change materials (PCM) were used in the ceiling and wall construction. The earth heat exchanger installed at a low depth of 1.2 m has an excellent electrical cooling coefficient of performance of 18, but with an average cooling power of about 1.5 kW does not contribute significantly to cooling load removal. Mechanical night ventilation with 2 air changes also delivered cold at a good coefficient of performance of 6 with 14 kW maximum power. However, the night air exchange was too low to completely discharge the ceilings, so that the PCM material was not effective in a warm period of several days. In the ground floor offices the heat removal through the floor to ground of 2–3 W m⁻² K⁻¹ was in the same order of magnitude than the charging heat flux of the ceilings. The number of hours above 26 °C was about 10% of all office hours. The energy performance of the building is excellent with a total primary energy consumption for heating and electricity of 107–115 kW h m⁻² a⁻¹, without computing equipment only 40–45 kW h m⁻² a⁻¹.     

Thermal performance and embodied energy analysis of a passive house – Case study of vault roof mud-house in India

This paper investigates thermal performance of an existing eco-friendly and low embodied energy vault roof passive house (or mud-house) located at Solar Energy Park of IIT Delhi, New Delhi (India). Based on embodied energy analysis, the energy payback time for the mud-house was determined as 18 years. The embodied energy per unit floor area of R.C.C. building (3702.3 MJ/m²) is quiet high as compared to the mud-house (2298.8 MJ/m²). The mud-house has three rooms with inverted U-shape roof and remaining three rooms with dome shape roof. A thermal model of the house consisting of six interconnected rooms was developed based on energy balance equations which were solved by using fourth order Runge Kutta numerical method. The predicted six room air temperatures were found in good agreement with the experimental observed data on hourly basis in each month for one year. The annual heating and cooling energy saving potential of the mud-house was determined as 1481 kW h/year and 1813 kW h/year respectively for New Delhi composite climate. The total mitigation of CO₂ emissions due to both heating and cooling energy saving potential was determined as 5.2 metric tons/year. The annual carbon credit potential of mud-house was determined as € 52/year. Similar results were obtained for the different climatic locations in India.     

Energy policy and energy market performance: The Argentinean case

In the early 1990s Argentina liberalized and privatized the energy system, trending to a total market oriented system and abandoning the use of energy policy. Since 2004, as a result of a boom in energy demand and constrains in energy supply, Argentina has gone through an energy problem mainly related to natural gas and electricity, which derived in energy shutdowns. In this frame, this study explores the role of energy policy and institutions in Argentina, with the aim of discussing whether it has been properly used to contrast the observed lack of coordination between fossil energy reserves management and the demand of fuels in power generation. The results of the analysis enhance the relevance of regulatory and control authorities, as well as the active use of long run energy policy for the energy system performance in order to avoid coordination failures between subsectors of the system. The relevance of energy consumption for the development process, and the particular characteristics of energy systems require a wide planning perspective.     

Technological-economic assessment and optimization of hydrogen-based transportation systems in China: A life cycle perspective

Hydrogen energy is increasingly incorporated into long-distance transportation systems. Whether the coupled hydrogen-based transportation system can achieve a sustainable business operation mode requires quantification of environmental and economic performance by a comprehensive cost-benefit analysis. This study proposes a cost-based life cycle assessment method to evaluate the environmental and economic benefits of hydrogen-based long-distance transportation systems. The innovative cost assessment method introduces internal and external economic costs to conduct a multi-scenario assessment. According to the key factors of mileage, government subsidies and hydrogen fuel prices, this research identifies the key cost component of the hydrogen-based transportation system in China by using a multilevel comparison with cell-driven and oil-fueled vehicles. The results show that hydrogen fuel cell electric vehicles are competitive in terms of both fuel costs and environmental costs. As hydrogen costs are expected to be gradually reduced by 43% in the future, hydrogen logistics vehicles and heavy trucks are expected to have better life-cycle economics than other energy vehicles by approximately 2030. Hydrogen buses will outperform other vehicles by approximately 2033, while hydrogen passenger cars will have a reduced life-cycle cost per kilometre within 0.1 CHY/km compared to other vehicles by approximately 2035. Ultimately, fuel consumption, average annual mileage, and hydrogen fuel cell electric vehicle policy are three factors that have greater impacts. Policy implications are put forward to implement optimal investment plan for hydrogen transportation systems.     

某下送风多功能厅气流组织及节能性的实测与分析

实测了采用下送风空调方式的某多功能厅的温度场和速度场。获得了夏季三种工况下的温度、速度分布及其随时间的变化。评价了该空调房间的节能性以及舒适状况。结果表明,在一定送风量和送风参数下能够满足舒适性要求,且具有较明显的节能效果,通风效率为1.7~3.2。     

Energy retrofit of commercial buildings: case study and applied methodology

Commercial buildings are responsible for a significant share of the energy requirements of European Union countries. Related consumptions due to heating, cooling, and lighting appear, in most cases, very high and expensive. Since the real estate is renewed with a very small percentage each year and current trends suggest reusing the old structures, strategies for improving energy efficiency and sustainability should focus not only on new buildings, but also and especially on existing ones. Architectural renovation of existing buildings could provide an opportunity to enhance their energy efficiency, by working on the improvement of envelopes and energy supply systems. It has also to be noted that the measures aimed to improve the energy performance of buildings should pay particular attention to the cost-effectiveness of the interventions. In general, there is a lack of well-established methods for retrofitting, but if a case study achieves effective results, the adopted strategies and methodologies can be successfully replicated for similar kinds of buildings. In this paper, an iterative methodology for energy retrofit of commercial buildings is presented, together with a specific application on an existing office building. The case study is particularly significant as it is placed in an urban climatic context characterized by cold winters and hot summers; consequently, HVAC energy consumption is considerable throughout the year. The analysis and simulations of energy performance before and after the intervention, along with measured data on real energy performance, demonstrate the validity of the applied approach. The specifically developed design and refurbishment methodology, presented in this work, could be also assumed as a reference in similar operations.     

Optimum energy evaluation and life cycle cost assessment of a hydrogen liquefaction system assisted by geothermal energy

In this study, analyses of the thermodynamic performance and life cycle cost of a geothermal energy-assisted hydrogen liquefaction system were performed in a computer environment. Geothermal water at a temperature of 200 °C and a flow rate of 100 kg/s was used to produce electricity. The produced electricity was used as a work input to liquefy the hydrogen in the advanced liquefaction cycle. The net work requirement for the liquefaction cycle was calculated as 8.6 kWh/kg LH₂. The geothermal power plant was considered as the work input in the liquefaction cycle. The hydrogen could be liquefied at a mass flow rate of 0.2334 kg/s as the produced electricity was used directly to produce liquid hydrogen in the liquefaction cycle. The unit costs of electricity and liquefied hydrogen were calculated as 0.012 $/kWh and 1.44 $/kg LH₂. As a result of the life cycle cost analysis of the system, the net present value (NPV) and levelized annual cost (LAC) were calculated as 123,100,000 and 14,450,000 $/yr. The simple payback period (N_spp) and discount payback period (N_dpp) of the system were calculated as 2.9 and 3.6 years, respectively.     

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.