Comprehensive Life Cycle Analysis Research Articles

Life-cycle analysis of hydrogen production from water electrolyzers

The United States' focus on decarbonization has spawned interest among policymakers in deploying water electrolysis technology for clean hydrogen production. However, water electrolyzers also raise concerns regarding their substantial use of carbon-intensive materials. Here, we conduct a comprehensive life-cycle analysis (LCA) of three prominent water electrolyzer technologies to investigate the environmental implications of their manufacturing and life cycles under different energy sources. All electrolyzer technologies employing low-carbon energy (nuclear, solar, or wind) exhibit life-cycle greenhouse gas (GHG) emissions of 0.3–2.4 kg-CO2-eq/kg-H2. This is significantly lower than the corresponding GHG emissions for hydrogen production via both conventional steam methane reforming and alternative autothermal reforming with carbon capture and storage (by > 50%). The well-to-gate GHG emissions of low-carbon electrolyzers (0–0.36 kg-CO2-eq/kg-H2) qualify for Tier I of the production tax credit in the U.S.’ Inflation Reduction Act of 2022, indicating their suitability for producing decarbonized hydrogen under this program.

Enhancing Concrete Performance through Sustainable Utilization of Class-C and Class-F Fly Ash: A Comprehensive Review

Integrating class-C and class-F fly ash (FA) as supplementary cementitious materials (SCMs) in concrete offers a promising pathway for sustainable construction practices. This study explores the pivotal role of FA in reducing carbon dioxide (CO2) emissions and improving concrete’s durability and mechanical properties through a comprehensive life cycle analysis (LCA). By blending FA with cement, significant reductions in CO2 emissions are achieved, alongside enhancements in the workability, compressive strength, and permeability resistance of the concrete matrix. This research elucidates the pozzolanic reaction between FA and calcium hydroxide (CH) during cement hydration, highlighting its contribution to concrete strength and durability. Through a range of comprehensive analysis techniques, including mechanical testing and environmental impact assessment, this study demonstrates the substantial benefits of prioritizing the utilization of class-C and class-F FA in sustainable construction. The findings underscore the industry’s commitment to environmentally conscious practices, promoting structural integrity and reducing ecological impacts. Overall, this research emphasizes class-C and class-F FA as critical components in achieving sustainable construction goals and advancing towards a more environmentally responsible built environment.

Sustainable End-of-Life Tyre Management: A Comprehensive Analysis of Environmental Impacts and Crumb Rubber Integration in Composite Concretes

The research explores pollution prevention strategies associated with end-of-life tyres (ELTs) through sustainable practices, focusing on repurposing ELTs into crumb rubber (CR) for use in composite concretes for civil engineering applications. Three disposal approaches are considered: recycling into crumb rubber for use in cement composites to enhance acoustic properties, incineration for cement production, and landfill disposal. The study aims to assess the environmental impact of each method, particularly in terms of carbon dioxide (CO2) emissions during the recycling phase, utilizing the OpenLCA program for a comprehensive life cycle analysis. The primary objective is to provide insights into the sustainability of incorporating recycled rubber in concrete mixes as fine aggregate to improve concrete acoustic and shock absorbance properties. The research also gathers data on CO2 emissions from ELT incineration for cement production and the environmental implications of ELT’s landfill disposal. By comparing these three strategies, the study offers a holistic perspective on the environmental ramifications of ELT management. Notably, a recent study highlights the energy recovery and CO2 emissions from ELT incineration, demonstrating the potential benefits of recycling. The research identifies a gap in existing studies, emphasizing the need to consider the entire life cycle, including the transportation and use stages. Notably, the use stage significantly contributes to environmental impacts, with carbon emissions ranging from 550 to 840 kg CO2 eq., per car tyre. Additionally, a proposed inventory analysis method evaluates greenhouse gas emissions from Portland cement concrete pavement construction, revealing that raw material production accounts for most emissions. The findings of this research are providing valuable insights for policymakers, industry professionals, and environmentalists aiming for sustainable practices in the construction sector. By allocating a fraction of tyre production CO2 emissions to obtain raw material for concrete composites, the study suggests a potential avenue for reducing environmental impact. Further calculations using the OpenLCA program may refine these recommendations.

Investigating social and environmental hotspots throughout the lifecycle of product-service systems in the early design stages

Product-Service Systems (PSS) have been recognized as potential game-changers for advancing sustainability. However, the sustainability of a PSS over traditional products and services is not automatic; it requires careful, intentional design. Despite a decade's progress in relevant literature, early-stage design assessment of a PSS – particularly from a life cycle standpoint and considering the social sustainability dimension – remains underexplored. This study introduces a framework for early-stage identification and analysis of potential environmental and social impacts within a PSS's life cycle to aid in decision-making and guide towards sustainable solutions. The framework's hotspot analysis, which combines life cycle assessment techniques, aims to pinpoint life cycle stages most susceptible to significant environmental and social impacts. Drawing on existing literature and expert evaluations, this approach offers designers preliminary insights into potential impacts, establishing a groundwork for comprehensive life cycle analysis once more detailed information on products, services, and organizational structures becomes available. The hotspot analysis not only addresses the lifecycle view of a PSS but also places emphasis on the oft-neglected social dimension of sustainability, marking an area ripe for further study. By supporting decision-making in the early design phase and encouraging scrutiny of various PSS concepts, this approach promotes the cultivation of sustainably-designed solutions.

Degradation of Plastic Materials through Small-Scale Pyrolysis: Characterization of the Obtained Hydrocarbons and Life Cycle Analysis

Plastic waste signifies a global predicament, aggravated by deficient management practices. Unearthing methods to repurpose energy from this waste is pivotal. This study delves into the pyrolytic degradation of low-density plastics to convert plastic waste into valuable products on a modest scale. A small-scale, low-CO2 emitting distiller was employed in the process. A zeolite was harnessed as a catalyst to augment the temperature and hasten the pyrolysis process. A comprehensive life cycle analysis was executed to assess the environmental impact of the process. In this scenario, zeolite-facilitated pyrolysis was more proficient compared to traditional thermal pyrolysis, generating a yield of 22.5% with the catalyst, contrasting with 18% without. A kinetic model was formulated, observing reaction mechanisms and temperature escalation and culminating in the extraction of aromatic oils. These oils were further distilled to produce liquid hydrocarbons, beginning the distillation at 60 °C with the catalyst. Characterization of the secured hydrocarbons was conducted using infrared, Raman spectroscopy, and gas chromatography, discovering compounds akin to gasoline, such as benzene, toluene, and xylenes. Additionally, the procedure exhibited a minimal environmental detriment, as validated by the life cycle analysis. This study concludes by highlighting the potential of small-scale, low-CO2 emitting pyrolytic degradation of low-density plastics for energy recovery from plastic waste, demonstrating the practical and environmental benefits of this avant-garde method.

Life cycle assessment of atmospheric environmental impact on the large-scale promotion of electric vehicles in China

Decarbonizing the transportation sector emerges as a pivotal step in addressing climate change. In recent years, rapid growth in China’s new energy automotive industry has significantly contributed to transportation decarbonization. However, environmental challenges in producing and recycling electric vehicles (EVs) may limit emission reduction benefits. In this study, we establish a comprehensive life cycle assessment model for vehicles to analyze the gap in air pollutant and greenhouse gas emissions between electric vehicles and internal combustion engine vehicles (ICEVs). Based on this model, the environmental benefits of further promoting electric vehicles in China are evaluated. Results reveal that, compared to ICEVs, EVs reduce life cycle emissions of CO2 by 12%, NOx by 69%, and VOCs by 9%. Primary constraints on EVs in emission reduction are traced to raw material and component production, notably lithium batteries. By 2025, under the low carbon EVs policy scenario, widespread EV production and sales could cut lifecycle emissions by 3.55 million tons of CO2, 3,6289 tons of NOx, and 4315 tons of VOCs. During the driving stage, these indicators contribute 495%, 124%, and 253%, respectively, to total emission reduction throughout the lifecycle. This study conducts a comprehensive lifecycle analysis of greenhouse gases and various air pollutants for Chinese EVs. It integrates the latest market trends, application progress, and policy guidelines into scenario design, identifying key sources and indicators of atmospheric pollution in the EV production chain. The findings offer valuable policy insights into China’s role in the global emission reduction process.

Substitution of Fossil Coal with Hydrochar from Agricultural Waste in the Electric Arc Furnace Steel Industry: A Comprehensive Life Cycle Analysis

The iron and steel industry remains one of the most energy-intensive activities with high CO2 emissions. Generally, the use of fossil coal as chemical energy in an electric arc furnace (EAF) makes up 40–70% of the total direct emissions in this steelmaking process. Therefore, substituting conventional fossil fuels with alternatives is an attractive option for reducing CO2 emissions. In this study, the environmental impacts of EAF-produced steel were comprehensively assessed using pulverized hydrochar as the charged and injected material as a replacement for fossil coal. An environmental analysis was performed based on the LCA methodology according to the framework of ISO 14044. This study evaluated two different outlines: the use of fossil coal and its replacement with hydrochar from the winemaking industry as a carbon source in the EAF steelmaking process. The environmental impacts from the manufacturing of the hydrochar were calculated using different scenarios, including novel industrial ways to use vinasse as a moisture source for the co-hydrothermal carbonization of vine pruning and exhausted grape marc (EGM). The environmental impacts per unit of steel were reported as a function of the ratio between the fixed carbon of the injected material and the material amount itself. The results highlight the sustainability of the hydrothermal carbonization process and the use of the hydrochar in EAF steelmaking. Moreover, the electricity mix used for the EAF process has significant relevance. The main outline of the results might assist decision-makers to determine which technological route is most likely to be effective in reducing future CO2 emissions from the iron and steel industry.

`A critical review on current status and environmental sustainability of pre-treatment methods for bioethanol production from lignocellulose feedstocks.

Lignocellulosic biomass resource has been widely used as a natural resource for the synthesis of biofuels and bio-based products through pre-treatment, saccharification and fermentation processes. In this review, we delve into the environmental implications of bioethanol production from the widely utilized lignocellulosic biomass resource. The focus of our study is the critical stage of pre-treatment in the synthesis process, which also includes saccharification and fermentation. By collecting scientific data from the available literature, we conducted a comprehensive life cycle analysis. Our findings revealed substantial differences in the environmental burdens associated with diverse pre-treatment methods used for lignocellulosic biomass. These results highlight the importance of selecting environmentally benign pre-treatment techniques to promote the sustainability of bioethanol production. Future research directions are suggested, emphasizing the optimization of pre-treatment processes to further mitigate their environmental impact.

Cradle-to-Grave Lifecycle Analysis of Greenhouse Gas Emissions of Light-Duty Passenger Vehicles in China: Towards a Carbon-Neutral Future

Vehicle electrification is considered a pathway for on-road transportation decarbonization in China. Different from the conventional gasoline vehicles whose emissions are mainly released from vehicle tailpipes, emissions of battery electric vehicles (BEVs) are from the upstream processes of electricity generation and vehicle manufacturing, thus a comprehensive lifecycle analysis and comparison of BEVs with gasoline vehicles is required to quantify the emission mitigation benefit of vehicle electrification and determine the path to a carbon-neutral future. In the study, we compare the cradle-to-grave (C2G) lifecycle greenhouse gas emissions of gasoline and electric vehicles in China and analyze the greenhouse gas emission reduction of vehicle electrification in different provinces. Results show that under the current technologies, the national average C2G GHG emissions for battery electric vehicles (BEVs) of 100 miles (i.e., 160 km) and 300 miles (i.e., 480 km) all-electric range (AER) are 231 and 279 g CO2eq/km, respectively, 22% and 5% lower than those for gasoline internal combustion engine vehicles (ICEVs). Improving vehicle fuel efficiency by hybridizing gasoline ICEVs can effectively reduce C2G emissions to 212 g CO2eq/km. At the provincial level, C2G GHG emissions of BEVs vary according to the provincial electricity mix. In eight provinces, C2G GHG emissions of BEVs with 300 miles AER (BEV300s) are higher than those of gasoline ICEVs due to the GHG-intensive coal-based electricity mix. In the future scenario, with low carbon fuels (such as high-level bioethanol blending gasoline) and electricity decarbonization, the national average C2G emissions of hybrid electric vehicles (HEVs) and BEV300s can be reduced to 55 and 73 g CO2eq/km, respectively. Further decrease of C2G GHG emissions relies on reducing vehicle-cycle emissions from material processing and vehicle component manufacturing.

Comparative economic and environmental assessments of furrow- and flood-irrigated rice production systems

Rice producers in the Mid-South of the United States face decreasing groundwater availability and increasing pumping depths which may jeopardize sustainable rice production. Recently, producers have started adopting furrow irrigated rice (FIR) which reduces irrigation requirements by approximately 17 % compared to conventionally flooded rice (CIR). Although driven by water savings and ease of planting and harvesting, as FIR does not require levies to be built, there are both yield (quantity) and milling (quality) concerns with FIR production. While some view FIR as a more sustainable production practice because of its reduced water usage, a comprehensive Life Cycle Analysis (LCA) has not been conducted to compare the two production systems. This study compares the economic (yield differences, NPV of water conserved and milling discounts/premiums) and environmental (a stepwise LCA which monetizes the holistic environmental of CIR and FIR on a per kg of rice basis) differences between CIR and FIR. Profitability results indicate that CIR more profitable and LCA results show that CIR is more environmentally sustainable. These results present a Gordian knot for policy makers and rice stakeholders alike as they struggle between a production practice that has a lower environmental impact (CIR) versus one that conserves water, reduces soil disturbance, and offers more flexibility to respond to market and weather conditions (FIR). Water savings has historically been a key focus of rice production from an environmental sustainability standpoint. Our research indicates that failure to both recognize and quantify holistic environmental metrics besides water savings may provide misleading recommendations.

Techno-Economic Analysis of ‘Solar-Powered’ Post-Combustion Carbon Capture

To solarize carbon capture industry and completely move away from the power plant (PP) steam cycle, a novel concept for solar-powered post-combustion carbon capture (SP-PCC) is proposed in this project. In this configuration, solvent regeneration directly occurs in a new design of “solar stripper” (So-St) network, sized and designed to replace the conventional desorption unit of the PCC. The present study evaluates the economic footprint of this SP-PCC technology in comparison with the typical PCC where the steam is totally bled from the PP steam cycle, and also the solar-assisted PCC (SA-PCC) where a portion of the steam is produced in the solar collector field (SCF) to contribute for the reboiler duty in the PCC. The CAPEX & OPEX, and the levelized cost of electricity (LCOE) is calculated for different scenarios for a 660 MWe coal-fired PP case-study located in Sydney, Australia. It is found that the LCOE of the SP-PCC is currently large and unprofitable as a result of 100% solar contribution for the thermal duty demand. However, under the same 100% solar energy contribution, the LCOE of the SA-PCC counterpart is prohibitively higher than that of the SP-PCC. Therefore, to fully solarize a carbon capture process, this novel SP-PCC would be the best technology option. Comprehensive analyses of economic parameters reveal potential areas for LCOE reductions. In order to realize the full potential of this new SP-PCC technology, future work should examine ways of leveraging on solvent thermochemical properties and process innovations. Furthermore, the enhanced sustainability aspects via preserving the steam production only for power generation must be fully addressed in a comprehensive life cycle analysis (LCA).

Comparative life cycle assessment of astaxanthin production with Haematococcus pluvialis in different photobioreactor technologies

Haematococcus pluvialis is one of the most abundant sources of natural astaxanthin when compared with other microorganisms, and has attracted the interest of the market thanks to its health benefits. We investigated the environmental performance of the cultivation of H. pluvialis and the astaxanthin production processes through a comprehensive Life Cycle Analysis (LCA). This study compares the potential environmental impact of three photobioreactors (PBR) available on the market: the flat panel airlift , the green wall panel , and the unilayer horizontal tubular PBR . These systems have different technical settings: the flat panel airlift has a double-sided light emitting diode (LED) illumination system and is placed inside a building; the green wall panel is located outside and equipped with one-side LED lighting; the unilayer horizontal tubular is placed outside without any artificial lighting. Two different functional units were considered: one kg of H. pluvialis (80% dw) and 1 kg of astaxanthin. Where 1 kg of astaxanthin was selected as functional unit, as the content of astaxanthin in the biomass is low, the system expansion method was applied.The LCA results, based on original data from pilot-scale production, indicate that the system design, and the energy mix used have a significant environmental impact, due to differences in algae productivities and energy demand. For indoor systems, even with light-emitting diodes (LED), the energy demand for lighting is the main contributor to climate change. This contribution decreases significantly if the share of renewable energy increases. In the case of the green wall panel another main climate change contributor is the material used for the diode production, including tin and molybdenum. Although the astaxanthin yield is higher in the flat panel airlift and green wall panel, electricity production systems still constitute an environmental burden. For this reason, the system with the lowest environmental impact is the unilayer horizontal tubular, i.e. the photobioreactor where no artificial light is used.

Woodscraper - highrise according to the circular economy

shortages, climate change and population growth with associated urbanization pose immense challenges to the construction industry. The question of sustainable building construction raises the need for innovative concepts, which address the increasing scarcity of raw materials, energy efficiency as well as space efficient construction to protect our climate. strategies become more and more the focus also of social interest So far, buildings are usually built and operated according to the take-make-waste principle[1]. This means that finite resources are no longer available for new uses through downcycling processes. The Woodscraper examines by way of example how far fully circulatable buildings are already possible today. Therefore the concept of Woodscrapers is based on the principles of Cradle-to-Cradle, Circular Economy and AktivPlus. As part of the “Deutsche Bundestiftung Umwelt (DBU)” -funded project, strategies for circular construction have been developed and implemented in the project through an integrated planning process, involving the competences of a planning-team, the early involvement of the authorities, as well as specialist planners and manufacturers. Synergies between construction, materials and building services have been identified and implemented meaningfully. A life cycle analysis ran in parallel, to quantify those potentials. The Woodscraper visualizes this added value in the construction and makes it perceptible through comprehensive lifecycle analysis during operation over its entire life cycle.

Forecasting Life Cycle CO2Emissions of Electrified Vehicles by 2030 Considering Japan’s Energy Mix

This paper presents a comprehensive life-cycle analysis of CO2(LCCO2) emissions from automobiles using a hybrid life-cycle inventory approach to predict the growth of electrified vehicles in Japan. Herein, the hybrid electric vehicle (HEV), plug-in HEV (PHEV), and battery electric vehicle (BEV) versions of the mass-produced Toyota Prius hatchback are analyzed, considering the automobile-usage environment in Japan. In particular, a breakeven analysis of HEV vs. PHEV vs. BEV is conducted in terms of LCCO2emissions that are affected by (i) outside air temperature and (ii) CO2emissions during power generation from the present day up to 2030. Our results show that HEV has the lowest LCCO2emissions when the current thermal-power-dependent electricity generation mix (average for 2012–2014) is considered, followed in order by PHEV and BEV. However, it is predicted that in 2030, PHEV will have the lowest LCCO2emissions, followed in order by HEV and BEV, as it is anticipated that nuclear and renewable energy sources will be widely available by 2030. PHEV is expected to gain popularity by 2030. Regarding BEV, large quantities of CO2emissions are emitted during battery production. Furthermore, due to the domestic electricity generation mix from the present day up to 2030, the LCCO2emissions of BEV will exceed those of HEV and PHEV.

Well-to-wheel greenhouse gas emissions of battery electric vehicles in countries dependent on the import of fuels through maritime transportation: A South Korean case study

Well-to-wheel (WTW) analysis of battery electric vehicles (BEVs) has been mainly performed in the U.S., China, and Europe, which are countries that can produce sizable amounts of fuels or import additionally required fuels through land transportation. However, the situation characterizing these countries is far different from that of countries dependent on the import of fuels through maritime transportation, such as Japan, South Korea, and Taiwan, because the dependence on fuel imports through maritime transportation affects not only the energy mix but also the complexity and results of WTW analysis. In addition, determining the WTW greenhouse gas (GHG) emissions of driving BEVs in these countries is very important since these countries have large amounts of GHG emissions and strong interests in the widespread adoption of BEVs. Therefore, unlike previous studies, this study evaluates the WTW GHG emissions of BEVs in South Korea as an example of such countries. To perform WTW analysis of BEVs, comprehensive life cycle analyses of five power generation fuels (coal, natural gas, petroleum-based fuel, uranium, and bio heavy oil) are conducted. In addition, ten different power generation technologies and two different electric grids (mainland and the Jeju Island) in South Korea are analysed. The fuel economies of BEVs and conventional vehicles are also considered for evaluating the WTW GHG emissions. The result of this study shows that import processes commonly increase the life cycle GHG emissions of power generation fuels. The GHG emissions of natural gas from the upstream process are ∼40% higher than those of the U.S due to the liquefaction and regasification required for importing natural gas. However, although natural gas produces large amounts of GHG emissions from the upstream process, the electricity generated from natural gas still produces the lowest GHG emissions among the fossil fuels like other countries due to the high efficiency of combined cycle systems. The life cycle GHG emissions of electricity of the Korean mainland and Jeju are calculated to be 578 g CO2 eq/kWh and 544 g CO2 eq/kWh, respectively, which are higher than that of the EU and lower than that of the U.S. and China. Driving BEVs in South Korea was found to have advantages of 90–110 g CO2 eq/km and 50–60 g CO2 eq/km on average over driving internal combustion engine vehicles (ICEVs) and hybrid electric vehicles (HEVs), respectively, not only on the Korean mainland but also on Jeju Island. Because the GHG emissions from the upstream process of major power generation fuels and the life cycle GHG emissions of the electricity from major power generation technologies are determined in this study, these results are expected to be informative for other countries, which may have different detailed generation mixes, in similar situations.

Transformation of Silver Nanoparticles in Sewage Sludge during Incineration.

Silver nanoparticles (Ag-NP) discharged into the municipal sewer system largely accumulate in the sewage sludge. Incineration and agricultural use are currently the most important strategies for sewage sludge management. Thus, the behavior of Ag-NP during sewage sludge incineration is essential for a comprehensive life cycle analysis and a more complete understanding of the fate of Ag-NP in the (urban) environment. To address the transformation of Ag-NP during sewage sludge incineration, we spiked metallic Ag(0)-NP to a pilot wastewater treatment plant and digested the sludge anaerobically. The sludge was then incinerated on a bench-scale fluidized bed reactor in a series of experiments under variable conditions. Complementary results from X-ray absorption spectroscopy (XAS) and electron microscopy-energy dispersive X-ray (EM-EDX) analysis revealed that Ag(0)-NP transformed into Ag2S-NP during the wastewater treatment, in agreement with previous studies. On the basis of a principal component analysis and subsequent target testing of the XAS spectra, Ag(0) was identified as a major Ag component in the ashes, and Ag2S was clearly absent. The reformation of Ag(0)-NP was confirmed by EM-EDX. The fraction of Ag(0) of the total Ag in the ashes was quantified by linear combination fitting (LCF) of XAS spectra, and values as high as 0.8 were found for sewage sludge incinerated at 800 °C in a synthetic flue gas atmosphere. Low LCF totals (72% to 94%) indicated that at least one relevant reference spectrum was missing in the LCF analysis. The presence of spherical Ag-NP with a diameter of <50 nm extending into the sub-nm range was revealed by electron microscopy analyses. The rapid formation of Ag(0)-NP from Ag2S during sewage sludge incineration, as demonstrated in this study, needs to be considered in the life cycle assessment of engineered Ag-NP.

Lifecycle climate impacts and economic performance of commercial-scale solar PV systems: A study of PV systems at Nevada’s Desert Research Institute (DRI)

The Desert Research Institute (DRI) in Nevada has recently installed eight solar PV systems with a cumulative nameplate capacity of 2.4MW that scale from 3kW to 1145kW. These systems supply approximately 40% of the total electricity used at DRI’s Reno and Las Vegas campuses. This work explored greenhouse gas (GHG) impacts and economic performance of these PV systems by developing and applying comprehensive life cycle analysis (LCA) combined with economic analysis. The LCA model was built using data appropriate for each type of panel used in the DRI systems. Power output was estimated using the National Renewable Energy Laboratory (NREL) model, called PVWatts®. The performance of PVWatts® was verified by comparison with actual measurements from one of DRI’s PV systems over an entire year. Lifecycle metrics quantified for the DRI systems include GHG intensity, energy payback time, cost payback time, and cost of avoided CO2.Manufacturing of PV modules is the major contributor to total lifecycle impacts of a solar PV system. The main benefits are solar electricity’s lower GHG intensity and lifecycle energy use compared with typical grid electricity. Model results showed the 25-year GHG intensity of DRI’s PV systems to be 35–58gCO2e/kWh, and the lifecycle energy use to be 0.586–0.898MJ/kWh. The cost payback times and return on investment (ROI) varied with system size. For the six systems larger than 50kW, the cost payback times ranged from 14.4 to 26.7years, and the 25-year ROI ranged from 0.95 to 2.0. The cost per tonne CO2e avoided by displacing grid electricity was between $100 and $180, which is 2–3 times as high as estimated costs for carbon capture from pulverized coal power plants.The modeled benefits of the PV systems are dependent upon the power mix of the grid electricity that is being displaced. As the grid becomes “cleaner” by elimination of coal and greater use of renewables, the CO2 reduction benefits are diminished. Changing from a “business as usual” scenario to cleaner grid scenarios was shown to reduce the GHG benefits of installed PV systems by up to 40%.

Nitrogen fertilizer and landscape position impacts on CO2 and CH4 fluxes from a landscape seeded to switchgrass

AbstractThis study was conducted to evaluate the impacts of N fertilizer and landscape position on carbon dioxide (CO2) and methane (CH4) fluxes from a US Northern Great Plains landscape seeded to switchgrass (Panicum virgatum L.). The experimental design included three N levels (low, 0 kg N ha−1; medium, 56 kg N ha−1; and high, 112 kg N ha−1) replicated four times. The experiment was repeated at shoulder and footslope positions. Soil CO2 and CH4 fluxes were monitored once every 2 weeks from May 2010 to October 2012. The CO2 fluxes were 40% higher at the footslope than the shoulder landscape position, and CH4 fluxes were similar in both landscape positions. Soil CO2 and CH4 fluxes averaged over the sampling dates were not impacted by N rates. Seasonal variations showed highest CO2 release and CH4 uptake in summer and fall, likely due to warmer and moist soil conditions. Higher CH4 release was observed in winter possibly due to increased anaerobic conditions. However, year to year (2010–2012) variations in soil CO2 and CH4 fluxes were more pronounced than the variations due to the impact of landscape positions and N rates. Drought conditions reported in 2012, with higher annual temperature and lower soil moisture than long‐term average, resulted in higher summer and fall CO2 fluxes (between 1.3 and 3 times) than in 2011 and 2010. These conditions also promoted a net CH4 uptake in 2012 in comparison to 2010 when there was net CH4 release. Results from this study conclude that landscape positions, air temperature, and soil moisture content strongly influenced soil CO2 fluxes, whereas soil moisture impacted the direction of CH4 fluxes (uptake or release). However, a comprehensive life cycle analysis would be appropriate to evaluate environmental impacts associated with switchgrass production under local environmental conditions.

Life Cycle Assessment of Energy Balance and Emissions of a Wind Energy Plant

Life cycle analysis (LCA) methodology was used to perform a quantitative, comparative analysis and rating of the construction and operation of a wind energy plant. For this case study, the Glacier Hills Wind Park (90 1.8-MW turbines in south-central Wisconsin) was evaluated. Significant environmental and economic benefits are often advertised with the installation of new wind energy facilities, although independent and comprehensive LCA and sustainable energy science are typically not implemented. Hence, a quantitative demonstration with LCA methodology of the life cycle emissions and environmental impact, from construction through operations, can greatly assist in highlighting significant areas of energy consumption and emissions during manufacturing, transportation, and construction of a wind farm. Results portray the amount of greenhouse gas emissions and energy consumption/generation over the life cycle of the wind park. Transportation of large components from overseas led to the consumption of considerable quantities of fossil fuel, responsible for up to 22 % of the total greenhouse gas emissions due to transportation. The energy payback ratio (25.5), energy payback time (12.3 months) and the total grams of equivalent CO2(eq) per kWh of energy (16.9) produced were calculated over the life time of this onshore wind farm.

A comprehensive life cycle analysis of cofiring algae in a coal power plant as a solution for achieving sustainable energy

Algae cofiring scenarios in a 360 MW coal power plant were studied utilizing an ecologically based hybrid life cycle assessment methodology. The impacts on the ecological system were calculated in terms of cumulative mass, energy, industrial exergy, and ecological exergy. The environmental performance metrics, including efficiency, loading, and renewability ratios were also quantified to assess the sustainability of cofiring scenarios from a holistic perspective. The analysis results revealed that cumulative mass and ecological exergy consumption were higher for algae cofiring compared to single coal firing due to high material and energy inputs for the algae cultivation. On the contrary, total energy and industrial exergy utilization were reduced with an increasing share of algae cofiring where algae is dried with solar energy. Additionally, natural gas dried algae cofiring scenarios had a lower renewability ratio in comparison with single coal firing. The results of this study are vital for the policy makers to decide on more environmentally friendly algae cofiring options by considering the potential impacts on ecological system.