Non-renewable Energy Demand Research Articles

Life-cycle assessment of electricity in Portugal

The Portuguese electricity mix is undergoing a significant shift away from the technologies that have dominated generation for the past decades. This article aims at assessing the environmental life-cycle impacts of electricity generation and supply in Portugal (PT), including: (i) modeling the main electricity generation systems; (ii) modeling the transmission and distribution (T&D) grid infrastructure; (iii) characterizing the evolution of the electricity sector in PT from 2003 to 2012; and (iv) discussing how the recent changes in the technology portfolio affected the environmental performance of the electricity generated and supplied. The life-cycle assessment methodology was used to quantify impacts in: non-renewable fossil energy demand (nREn), global warming (GW), abiotic depletion (AD), acidification (AC), eutrophication (ET), photochemical oxidation (PO) and ozone layer depletion (OD). From 2003 to 2012, an overall reduction of the environmental impacts was achieved. In particular, since 2008, electricity generation impacts in AC and PO dropped sharply as a result of the installation of desulphurization (62% reduction in AC; 74% reduction in PO) and denitrification (5% reduction in AC) systems in coal power plants (PP), as well as the phase out of large fuel oil PP. For NREn, AD and GW, the reduction of impacts was less pronounced (9–22% in the generation mix; 14–22% in the supply mix). T&D grid added 5–14% to the environmental impacts due to infrastructure (<5%) and T&D losses (5–9%). Despite the large increase in renewable capacity (especially wind) and the investments in lower-carbon fossil fuel technologies (natural gas), electricity generation still relies heavily on coal. There is, however, potential to further reduce environmental impacts in key categories (NREn, AD and GW) since there is significant available capacity of natural gas combined cycle currently underutilized.

Environmental life cycle assessment of bio-fuel production via fast pyrolysis of corn stover and hydroprocessing

A comparative life cycle assessment (LCA) of biofuel production from corn stover fast pyrolysis and subsequent hydrotreating and hydrocracking was conducted based on the Greenhouse gases Regulated Emissions and Energy use in Transportation (GREET) model. Three different cases were investigated as a result of different hydrogen treatment in bio-oil upgrading process. Environmental impacts such as non-renewable energy demand and Global Warming Potential (GWP) were primarily evaluated for 1MJ biofuel produced. All the results showed obvious environmental benefits compared with conventional gasoline and diesel based on the year of 2010. The results of Case 1 in which hydrogen was provided by external natural gas reforming displayed a reduction of 67.5% in net non-renewable energy demand and a reduction of 69.1% in net GWP in contrast to conventional gasoline and diesel. Net non-renewable energy demand was lowered by 76.6% and net GWP was reduced by 73.0% in Case 2 where 35% of bio-oil aqueous phase was consumed by steam reforming for hydrogen production. Case 3 gained an obvious advantage on both environmental aspects over the others, in which surplus hydrogen from steam reforming of whole aqueous phase of bio-oil was obtained as a coproduct. The results displayed a significant net non-renewable energy reduction of 147.5% and a net GWP reduction of 119.4%. However, the outcomes indicated decreasing biofuel yields from Case 1 to Case 3 compared with increasing environmental benefits. The biofuel yields of three cases were 31.2%, 23.7% and 11.5% respectively in this work.

The Trade‐off Between Environmental Impacts in Water Recycling Systems Using Industrial Effluent

SummaryA life cycle assessment was conducted on three industrial effluent water recycling options using a one‐, two‐, and three‐stage effluent treatment plant composed of clarification, aerobic treatment, and ultrafiltration processes. The impact categories dominated by energy use and the category of freshwater use were then further investigated and compared between each recycling system. A dual functional unit of recycled water delivered and effluent treated was identified to make the recycling options functionally equivalent. Three‐stage water recycling was the environmentally preferred option, with all three water recycling options investigated producing similar environmental impacts in most impact categories, with the exception of freshwater use, where the one‐ and two‐stage treatment options performed significantly worse than the three‐stage treatment. It was found that the impact categories of global warming potential and nonrenewable energy demand did not directly correlate with each other as a result of direct greenhouse gas emissions from sludge disposal.The construction of the equivalent systems shows that external systems required for functional equivalence are important in water recycling comparisons, and considering dual functional units is important for comparing water recycling options. With the increasing prevalence of industries utilizing biomass and other renewable fuels, it is becoming more apparent that measuring energy usage is not sufficient, and the specific impacts and damages associated with energy consumption need to be evaluated. This study provides a framework to identify opportunities in industrial wastewater management, which can be particularly important in industries with large effluent flows and high organic loadings.

Heating and cooling in high-rise buildings using facade-integrated transparent solar thermal collector systems

New facades of high-rise buildings often include renewable energy converters to allow “green building” operation. At the same time, numerous tenants value visual transparency. Transparent solar thermal collectors (TSTCs) aim at decreasing the non-renewable primary energy demand and increasing the visual transparency at the same time. On the one hand, this paper presents the main modelling challenges that arise when considering building facades and especially integrated TSTC systems. New transient systems simulation (TRNSYS) [Beckman, W. A., L. Broman, A. Fiksel, S. A. Klein, E. Lindberg, M. Schuler, and J. Thornton. 1994. “TRNSYS The Most Complete Solar Energy System Modelling and Simulation Software.” Renewable Energy 5 (1–4): 486–488] types have been especially developed for this purpose. A simplified model is presented for comparison purposes. On the other hand, the overall performance for a building with facade-integrated TSTC, as measured by its non-renewable primary energy demand, is treated. This is achieved by considering a complete simulation model coupling the TSTC, building and heating, ventilation and air conditioning operation. Possibilities for primary energy savings are investigated using the building mass as additional thermal storage.

The carbon footprint and non-renewable energy demand of algae-derived biodiesel

We determine the environmental impact of different biodiesel production strategies from algae feedstock in terms of greenhouse gas (GHG) emissions and non-renewable energy consumption, we then benchmark the results against those of conventional and synthetic diesel obtained from fossil resources. The algae cultivation in open pond raceways and the transesterification process for the conversion of algae oil into biodiesel constitute the common elements among all considered scenarios. Anaerobic digestion and hydrothermal gasification are considered for the conversion of the residues from the wet oil extraction route; while integrated gasification–heat and power generation and gasification–Fischer–Tropsch processes are considered for the conversion of the residues from the dry oil extraction route. The GHG emissions per unit energy of the biodiesel are calculated as follows: 41g e-CO2/MJb for hydrothermal gasification, 86g e-CO2/MJb for anaerobic digestion, 109g e-CO2/MJb for gasification–power generation, and 124g e-CO2/MJb for gasification–Fischer–Tropsch. As expected, non-renewable energy consumptions are closely correlated to the GHG values. Also, using the High Dimensional Model Representation (HDMR) method, a global sensitivity analysis over the entire space of input parameters is performed to rank them with respect to their influence on key sustainability metrics. Considering reasonable ranges over which each parameter can vary, the most influential input parameters for the wet extraction route include extractor energy demand and methane yield generated from anaerobic digestion or hydrothermal gasification of the oil extracted-algae. The dominant process input parameters for the dry extraction route include algae oil content, dryer energy demand, and algae annual productivity. The results imply that algal biodiesel production from a dried feedstock may only prove sustainable if a low carbon solution such as solar drying is implemented to help reducing the water content of the feedstock.

Life Cycle Assessment of Representative Swiss Road Pavements for National Roads with an Accompanying Life Cycle Cost Analysis

The subject of this paper is an environmental life cycle assessment (LCA) and life cycle cost analysis (LCCA) of processes needed to construct and maintain representative Swiss asphalt, concrete, and composite pavements (including subbase layers) applicable for the Swiss national road network over a period of 75 years. The environmental indicators analyzed are the global warming potential indicator, the nonrenewable cumulative energy demand, and the Swiss ecological scarcity indicator. Processes of the use phase of the road (fuel consumption, noise, etc.) have been evaluated qualitatively based on intensive research. The study shows that the global warming potential of concrete and asphalt pavements equilibrates over the analysis period and that concrete pavements compared to asphalt and composite pavements offer advantages in regards to the nonrenewable cumulative energy demand, the ecological scarcity indicator, and life cycle costs. The qualitative evaluation of the processes of the use phase shows for example the positive qualities of concrete pavements regarding fuel consumption and permanent noise properties.

Life-cycle performance of indirect biomass gasification as a green alternative to steam methane reforming for hydrogen production

The environmental performance of hydrogen production via indirect gasification of poplar biomass was evaluated following a Life Cycle Assessment approach. Foreground data for the study were provided mainly from process simulation. The main subsystems and processes that contribute to the environmental impacts were identified. Thus, poplar production and direct emissions to air from the processing plant were found to be the main sources of environmental impact. Furthermore, a favourable (positive) life-cycle energy balance was estimated for the gasification-based system.The environmental profile of hydrogen from poplar gasification was compared with that calculated for hydrogen from conventional steam methane reforming according to inventory data also obtained through process simulation. Gasification-derived biohydrogen was generally found to be a promising hydrogen fuel, with reduced greenhouse gas emissions and a low non-renewable energy demand. However, its suitability depends on the evaluated impact categories. Moreover, the biomass demand should be minimized to enhance the efficiency of the system.

Life-cycle assessment of Fischer–Tropsch products from biosyngas

This article addresses the life-cycle assessment of an energy conversion system for the coproduction of fuels and electricity from a gasification-based biosyngas feedstock via Fischer–Tropsch synthesis coupled with a combined-cycle process. Inventory data obtained mainly through process simulation are used to evaluate the environmental performance of the system in terms of abiotic depletion, global warming, ozone layer depletion, photochemical oxidant formation, land competition, acidification, and eutrophication. Furthermore, the cumulative non-renewable energy demand of the system is quantified and used in the calculation of the life-cycle energy balance of the system, which is found to be positive.Biosyngas generation arises as the main source of impact, with a much higher contribution than the rest of processes (production of catalysts, waste treatment, etc.). Electricity, diesel, gasoline and surplus hydrogen are the products of the system. The environmental profiles of these bioproducts are calculated and compared with those of fossil diesel, rapeseed biodiesel, soybean biodiesel, fossil gasoline, corn bioethanol, steam-methane reforming hydrogen, and the EU electrical grid. Overall, the bioproducts from the evaluated system are found to be promising alternatives to current energy products from a life-cycle environmental perspective.

Mitigating Climate Change in Nigeria: Fuel Subsidy Removal as a Possible Policy Option

This paper argues that policies that discourage the demand for non-renewable energy can be used to cut down CO2 emission as it would help to discourage consumption patterns away non-renewable energy sources. The transmission mechanism can be deduced from the high price that the withdrawal of fuel subsidy would bring and the resultant downward adjustment in non-renewable energy use in consumption and production (such as emission from vehicles) which would bring about reduction in total emission. The study focused on Nigeria as a significant oil producing country in Sub Saharan Africa and employs narrative method for its analysis. The study concludes that while fuel subsidy removal policy (in the short term) would have welfare implications, in the long run, the policy would bring about greener growth and enhance sustainable development.

Significance of the use of non-renewable fossil CED as proxy indicator for screening LCA in the beverage packaging sector

Purpose This study discusses the significance of the use of non-renewable fossil cumulative energy demand (CED) as proxy indicator in the beverage packaging sector, in order to detect those situations in which companies can benefit from the use of proxy indicators before a full life cycle assessment (LCA) application. Starting from a case study of two milk containers, the objectives of this paper are to assess if the use of this inventory indicator can be a suitable proxy indicator both (1) to decide which is the packaging alternative with the lowest environmental impact and (2) to identify the most impacting process units of the two products under study.

Preliminary assessment of plastic waste valorization via sequential pyrolysis and catalytic reforming

In this article, a life cycle assessment approach is used to carry out a preliminary assessment of the environmental and energy performance of a specific chemical recycling and recovery system that supplies a variety of petrochemical blendstocks through the sequential pyrolysis and catalytic reforming of plastic wastes. Characterization results are presented for a selection of seven impact categories: abiotic depletion, global warming, acidification, eutrophication, ozone layer depletion, photochemical oxidant formation and cumulative non-renewable energy demand. From a combined environmental and energy perspective, the results suggest the suitability of this system for plastic waste valorization. However, improvement actions aimed at reducing the thermal energy demand and mitigating direct emissions to the air should be undertaken. Furthermore, the environmental profiles of the proposed petrochemical blendstocks are compared with those of conventional energy products. A comparison among this chemical recycling and recovery system and two conventional management practices (municipal incineration and landfilling) is also addressed. The results show that the considered system could entail relevant environmental and energy benefits when compared to conventional energy systems and waste management strategies.

Environmental analysis of new construction and maintenance processes of road pavements in Switzerland

The subject of this paper is an environmental analysis of processes needed to construct (material production, pavement construction, transport) and maintain (pavement deconstruction, recycling, material production, pavement construction, transport) representative Swiss asphalt, concrete and composite pavements (including subbase layers). The analysed environmental indicators are the IPCC Global Warming Potential indicator, the Ecological Scarcity Indicator and the Non-renewable Cumulative Energy Demand indicator. It is shown that material production processes have the largest impact on the values of the analysed indicators, and that pavement construction and deconstruction processes have a marginal impact on the analysed indicators in comparison to material production, transport and recycling processes. It is also demonstrated that the values of the IPCC Global Warming Potential indicator and the Ecological Scarcity indicator for the processes needed to construct and maintain concrete and composite pavements are higher than those for all processes required to construct and maintain asphalt pavements, due to the greater thickness of concrete and composite pavements. The values of the Non-Renewable Cumulative Energy Demand indicator are higher for processes applied to construct and maintain asphalt pavements than for concrete pavements, due to the use of bitumen within asphalt pavements, which causes a depletion of fossil energy resources.

Environmental Impacts ofJatropha curcasBiodiesel in India

In the context of energy security, rural development and climate change, India actively promotes the cultivation of Jatropha curcas, a biodiesel feedstock which has been identified as suitable for achieving the Indian target of 20% biofuel blending by 2017. In this paper, we present results concerning the range of environmental impacts of different Jatropha curcas cultivation systems. Moreover, nine agronomic trials in Andhra Pradesh are analysed, in which the yield was measured as a function of different inputs such as water, fertilizer, pesticides, and arbuscular mycorrhizal fungi. Further, the environmental impact of the whole Jatropha curcas biodiesel value chain is benchmarked with fossil diesel, following the ISO 14040/44 life cycle assessment procedure. Overall, this study shows that the use of Jatropha curcas biodiesel generally reduces the global warming potential and the nonrenewable energy demand as compared to fossil diesel. On the other hand, the environmental impacts on acidification, ecotoxicity, eutrophication, and water depletion all showed increases. Key for reducing the environmental impact of Jatropha curcas biodiesel is the resource efficiency during crop cultivation (especially mineral fertilizer application) and the optimal site selection of the Jatropha curcas plantations.

LCA of biomethane

As a renewable substitute for natural gas in the pipeline system, biomethane is a key option on the way to sustainable, renewable energy supplies. This paper evaluates biomethane production from energy crops with respect to its environmental impact and energy efficiency, taking into consideration own measurements and experience data from a modern, commercial plant as well as current studies. According to this study the specific GHG emissions associated with the production of biomethane amount to as little as 44.6 g CO 2eq/kWh, corresponding to an overall GHG emission reduction of 82% compared with natural gas. The specific non-renewable energy demand of the entire process is very low at only 12%. These two indicators are due either to environmentally friendly plant cultivation (fermenter residues used as fertilizer) or to optimized plant design and operation (amine upgrading, renewable process heat, gas-tight equipment, industrial process control system).

Life cycle assessment of biodiesel production from free fatty acid-rich wastes

Environmental analyses of energy systems usually lack a comprehensive perspective that takes into account their life cycle and a set of relevant impact categories. The present study tries to fulfil this need in the field of biofuel production from free fatty acid-rich wastes, therefore providing a life cycle assessment of four biodiesel production systems including esterification–transesterification of waste vegetable oils (used cooking oil) and animal fats (beef tallow, poultry fat), and in situ transesterification of sewage sludges. Reference inventory data for these systems were gathered from a literature review. Thereafter, environmental characterization values were computed for a selection of impact categories: global warming, acidification, eutrophication, ozone layer depletion, photochemical oxidant formation, and cumulative non-renewable energy demand. A comparison among the environmental profiles of these second generation biodiesel alternatives and those of first generation rapeseed and soybean biodiesel fuels and conventional low-sulphur diesel was also performed through a well-to-wheels analysis. Thus, biodiesel from waste vegetable oils potentially entailed the most favourable environmental performance. Nevertheless, actions aimed at minimizing thermal and electric energy demands are encouraged as they would lead to relevant environmental improvements.

Environmental assessment of dehydrated alfalfa production in Spain

Alfalfa is the major forage crop produced in temperate regions worlwide. Although this crop is currently used mainly for producing high-value livestock feed, its application for bioenergy production is a recent focus of interest. Even though it is not mandatory, alfalfa is normally dried in order to improve the quality of the final product. In this study, Life Cycle Assessment (LCA) was used to quantify the environmental impacts linked to alfalfa production in the major cultivation zone in Spain (Ebro Valley), including field activities, dehydration and transport to farms for livestock feeding. In addition, the identification of the most relevant processes contributing to the environmental impact and the potential improvements actions were also defined as objectives. Inventory data were obtained mainly from interviews with farmers complemented with published literature and comments from experts. LCA results were obtained for global warming, acidification, eutrophication, photochemical oxidant formation, land use, non-renewable cumulative energy demand and human, terrestrial and aquatic ecotoxicities. Within the life cycle of alfalfa, the dehydration process, production of phosphate fertilizer, application of nitrogen fertilizers and pesticides, water consumption and final transport to the consumer (by road and ship) were identified as hot spots. Based on these, some improvement measures were proposed and evaluated: (i) reduction of the moisture content of alfalfa and the use of a higher percentage of biomass for combustion in the dehydration process, (ii) no application of nitrogen fertilizer in maintenance years and (iii) use of more efficient trucks for transport. Their implementation would produce significant reduction of eutrophication, global warming, acidification, non-renewable cumulative energy demand and, to a lesser extent, photochemical oxidation formation and human toxicity impacts.

The role of flexible packaging in the life cycle of coffee and butter

The role of flexible packaging in the life cycle of coffee and butter

Energy and CO 2 emissions performance assessment of residential micro-cogeneration systems with dynamic whole-building simulation programs

Micro-cogeneration, also termed micro combined heat and power (MCHP) or residential cogeneration, is an emerging technology with the potential to provide energy efficiency and environmental benefits by reducing primary energy consumption and associated greenhouse gas emissions. The distributed generation nature of the technology also has the potential to reduce losses due to electrical transmission and distribution inefficiencies and to alleviate utility peak demand problems. Detailed MCHP models for whole-building simulation tools, developed in Annex 42 of the International Energy Agency (IEA) Energy Conservation in Buildings and Community Systems Programme, have been used to conduct a performance assessment study for a number of micro-cogeneration systems and residential buildings. Annual non-renewable primary energy (NRPE) demand and CO 2-equivalent (CO 2-eq) emissions were determined by simulation for different cogeneration technologies, namely natural gas-fuelled solid oxide (SOFC) and polymer electrolyte membrane fuel cells, Stirling and internal combustion engines. These were compared to the reference system with a gas boiler and electricity supply from the grid. A ground-coupled heat pump system was also analysed for comparison. The cogeneration units were integrated in single and multi-family houses of different energy standard levels. Two different electricity generation mixes were considered: European mix and combined cycle power plant (CCPP). For the MCHP devices, detailed dynamic component models as well as simplified performance map models were used, developed and calibrated with either results from laboratory experiments or with manufacturer data. The simulations were performed using the whole-building simulation programme TRNSYS, using domestic hot water and electric demand profiles specified in IEA Annex 42. Combinations of three demand levels were analyzed. In NRPE demand, for the European electricity mix, most MCHP systems offered reductions (up to 34%) in comparison with the gas boiler reference system and crediting the electricity exported to the grid. For the CCPP electricity generation mix, the largest NRPE reductions resulted for the ground-coupled heat pump systems (up to 29%). The maximum reduction with a cogeneration system was 14%. In terms of CO 2-eq emissions, most cogeneration systems offered reductions for the European electricity mix (up to 22%). However, maximum reductions resulted for the heat pump system (23%). For the CCPP mix, maximum reductions by far again resulted for the heat pump systems (up to 29%). The maximum reduction for a cogeneration system was achieved with the ICE system in the single-family house (14%).

Performance assessment of fuel cell micro-cogeneration systems for residential buildings

The reduction of greenhouse gas emissions in the building sector to a sustainable level will require tremendous efforts to increase both energy efficiency and the share of renewable energies. Apart from the lowering of energy demand through better insulation and fenestration, small combined heat and power (micro-cogeneration) systems may help improve the situation on the supply side by cutting both the non-renewable energy demand for residential buildings and peak loads in the electric grid. Though still on the brink of market entry, fuel cells are the focus of interest as the prime technology for such systems. In this study, a methodology for assessing the performance of such systems in terms of primary energy demand and the CO 2 emissions by transient computer simulations is established, and demonstrated for a natural gas driven solid oxide fuel cell (SOFC) and, to a lesser extend, a polymer electrolyte fuel cell (PEFC) home fuel cell cogeneration system. The systems were evaluated for different grid electricity generation mix types and compared to traditional gas boiler systems. The interaction with hot water storage and solar thermal collectors, and the impact of storage size and predictive control was analyzed. Typical heat and electricity demand load profiles for different types of residential buildings and occupancy were considered, and the sizing of the fuel cell system in relation to the heat demand of the building was analyzed. Primary energy savings decline for cases with lower heat demand and for cases with solar thermal systems, and peak for fuel cell systems sized in accordance with the heat demand of the building. Future assessments of fuel cell systems will need a refined methodology, and depend on realistic performance characteristics and models that accurately consider dynamic conditions.