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EU targets require nearly zero energy buildings (NZEB) by 2020. However few monitored examples exist of how NZEB has been achieved in practise in individual residential buildings. This paper provides an example of how a low-energy building (built in 2006), has achieved nearly zero energy heating through the addition of a solar domestic hot water and space heating system (“combi system”) with a Seasonal Thermal Energy Store (STES). The paper also presents a cumulative life cycle energy and cumulative life cycle carbon analysis for the installation based on the recorded DHW and space heating demand in addition to energy payback periods and net energy ratios. In addition, the carbon and energy analysis is carried out for four other heating system scenarios including hybrid solar thermal/PV systems in order to obtain the optimal system from a carbon efficiency perspective. [ABSTRACT FROM AUTHOR]

Highlights: [•] Wintering cultivation of algae in artificial wastewater was investigated. [•] pH regulation could improve the nutrient removal and biomass productivity. [•] High lipid content and productivity were obtained by regulating pH. [•] Biodiesel yield in the pH-regulated group was 19.44% of dry weight. [•] It is efficient to grow C. zofingiensis in winter by pH regulation using acetic acid. [ABSTRACT FROM AUTHOR]

• Life cycle assessment of utility-scale solar energy is performed. • Upstream production and assembly are the most emission-intensive life cycle stages. • Energy use during production and plant lifetime are the most sensitive parameters. • The system shows a net energy production with a net energy ratio up to 6.6. • The life cycle GHG emissions range from 98.3 to 149.3 g CO 2 eq /kWh. Grid-connected utility-scale solar PV has emerged as a potential pathway to ensure deep decarbonization of electricity in regions with fossil fuel-dominated energy mixes. Research on utility-scale solar PV projects mainly focuses on assessing technical or economic feasibility. Environmental performance assessments of large-scale solar applications are scarce. There is limited information on the greenhouse gas (GHG) emissions and energy footprints of utility-scale solar energy systems. Earlier studies conducted on small-scale solar systems have limited application in the grid system. We developed a comprehensive bottom-up life cycle assessment model to evaluate the life cycle GHG emissions and energy profiles of utility-scale solar photovoltaic (PV) system with lithium-ion battery storage to provide a consistent electricity supply to the grid with peak load options. We conducted a case study for a fossil fuel-based energy jurisdiction, Alberta (a western province in Canada). The results of the energy assessment show that raw material extraction, production, and assembly of solar panels are the key drivers, accounting for 53% of the total consumption. Energy consumed during battery manufacturing is responsible for 28%. The system shows a net energy production with a mean net energy ratio as high as 6.6 for two-axis sun tracking orientation. The life cycle GHG emissions range from 98.3 to 149.3 g CO 2 eq /kWh with a mean value of 123.8 g CO 2 eq /kWh. The largest emissions contribution is due to the manufacturing of batteries, 54% of the total emissions. The solar PV system offers a mean energy payback time of 3.8 years (with a range of 3.3 to 4.2 years). The results are highly sensitive to the expected lifetime of the system, the panel's peak wattage, and process energy consumption at various life cycle stages. [ABSTRACT FROM AUTHOR]

Abstract: In the current scenario of depleting energy resources, increasing food insecurity and global warming, Jatropha has emerged as a promising energy crop for India. The aim of this study is to examine the life cycle energy balance for Jatropha biodiesel production and greenhouse gas emissions from post-energy use and end combustion of biodiesel, over a period of 5years. It’s a case specific study for a small scale, high input Jatropha biodiesel system. Most of the existing studies have considered low input Jatropha biodiesel system and have used NEB (Net energy balance i.e. difference of energy output and energy input) and NER (Net energy ratio i.e. ratio of energy output to energy input) as indicators for estimating the viability of the systems. Although, many of them have shown these indicators to be positive, yet the values are very less. The results of this study, when compared with two previous studies of Jatropha, show that the values for these indicators can be increased to a much greater extent, if we use a high input Jatropha biodiesel system. Further, when compared to a study done on palm oil and Coconut oil, it was found even if the NEB and NER of biodiesel from Jatropha were lesser in comparison to those of Palm oil and Coconut oil, yet, when energy content of the co-products were also considered, Jatropha had the highest value for both the indicators in comparison to the rest two. [Copyright &y& Elsevier]

Abstract: This study analyzes the energy balance of a bioethanol production system from high-yield rice plant in Japan. Two systems are considered in which rice is converted to ethanol: one in which cellulose feedstocks, straw and husk, are used for cogeneration (scenario 1), and the other in which they are converted to ethanol, and byproducts such as lignin and unreacted holocellulose are used for cogeneration (scenario 2). Energy input in the agricultural process including transportation is estimated to be 52.3GJ/ha from an Input Output Table. The heating values of produced rice and cellulose feedstocks are 120.7GJ/ha and 162.3GJ/ha, respectively. The net energy balance (NEB) of scenario 1 is 129.2GJ/ha, which produces 3.6kL/ha of ethanol and 9420kWh/ha of external electricity. On the other hand, NEB of scenario 1 is 11.7GJ/ha, which produces 7.1kL/ha of ethanol. Both NEBs are positive, but NEB of scenario 2 is much higher than that of scenario 1. An acid hydrolysis technology of cellulosic biomass applied to scenario 2 needs a large amount of heat energy for sulfuric acid recovery. If an enzyme hydrolysis of cellulosic biomass is developed, there is a possibility of improving NEB of scenario 2. [Copyright &y& Elsevier]

• 1-ha microalgal plant based on novel photobioreactor design has NER of 3.0. • Integrated PV module produces energy excess to requirements for plant operation. • NER for novel photobioreactor comparable to agricultural biofuel crops. • Spectral selection and PV technologies result in standalone operation. • Novel photobioreactor offers energy and water sustainable production of microalgae. The need for thermal regulation in microalgal photobioreactors is a significant impediment to their large-scale adoption. The energy costs associated with thermal regulation alone can easily result in a negative energy balance. Self-sustaining photovoltaic powered photobioreactors that do not require cooling systems provide an opportunity to maximize biomass productivity, generate local electricity, reduce thermal regulation requirements, and significantly improve the energy balance of the system. Net energy analysis of a spectrally-selective, insulated-glazed photovoltaic photobioreactor (IGP) with an integrated capability for renewable electricity generation used to cultivate Nannochloropsis sp. without freshwater-based cooling resulted in a net energy ratio of 2.96, a figure comparable to agricultural bio-oil crops such as Jatropha and soybean. Experimental data from pilot-scale operation of this novel photobioreactor producing Nannochloropsis biomass under outdoor conditions was extrapolated to a 1-ha IGP installation. Annual biomass productivity reached 66.0-tons dry weight ha−1, equivalent to overall energy output of 1696.2 GJ ha−1. The integrated semi-transparent photovoltaic panels generated an additional 1126.8 GJ ha−1 yr−1 (313.0 MWh ha−1 yr−1). Energy demands from plant building materials, machinery, fertilizers, plant operations, and biomass harvesting constituted total energy input with a combined value of 707.3 GJ ha−1 yr−1. Comparison with a conventional photobioreactor requiring passive evaporative cooling showed novel photobioreactor had a 73% greater net energy ratio. Nannochloropsis cultivation in IGP system ensured co-production of lipid and protein of 34.7 and 25.7-tons ha−1 yr−1, respectively. These results suggest that this novel photobioreactor could be a viable and sustainable biomass production technology for mass microalgal cultivation. [ABSTRACT FROM AUTHOR]

• Algal consortium cultivated outdoor in wastewater without using external energy. • Average biomass productivity of 3.48 ± 0.44 gm−2 d−1 under natural conditions. • Biomethane vs biocrude yield for different energy conversion routes compared. • Net Energy Ratio (Hydrothermal liquefaction) > Net Energy Ratio (anaerobic digestion). • Existing bottlenecks in algal biofuels feasibility discussed with possible solution. Real-time studies highlighting the actual bottlenecks of microalgae-based biofuels are needed to overcome the limitations of assumption-based approach. In the present study, an algal consortium consisting of Chlorella pyrenoidosa and Phormidium, was cultivated in municipal wastewater under outdoor conditions in a pilot scale (100 L) attached biofilm reactor during January-February 2018. No energy was used to maintain the cultivation conditions (temperature, light intensity/duration). After 6 days of hydraulic retention time, the consortium showed 53–87% reduction in the nutrients' concentrations of the selected wastewater. Consistent biomass productivity of 3.48 ± 0.44 g m−2 d−1 was observed, and its biochemical composition showed that it was rich in lipids (35.20 ± 0.63% of total solids). The wastewater grown algal biomass was subjected to anaerobic digestion at 37 °C for 30 days and hydrothermal liquefaction at 27 bars and 230 °C for 20 min to produce biomethane or biocrude, respectively. On performing the biomethane potential assay, a cumulative biomethane production of 346.59 ± 5 mL g−1 VS was observed. The theoretical methane production and stoichiometric methane potential calculated for the biomass was 504 mL g−1 VS and 591 mL g−1 VS, respectively, showing a digestibility of 58.5%. Hydrothermal liquefaction of the wastewater grown biomass gave biocrude yield of 43 ± 2% (dried biomass basis) rich in aldehydes/ketones/fatty acids. Net energy ratios for the two processes were compared. Net energy ratio for algal cultivation integrated with anaerobic digestion was found to be 0.007 and for that with hydrothermal liquefaction was found to be 0.08, proving it to be a more energy efficient process. [ABSTRACT FROM AUTHOR]

Abstract: Biodiesel from palm oil has been considered for partial substitution of diesel fuel for transportation in Thailand. The Thai government recently has set up a production target of 8.5million liters per day of palm oil-based biodiesel by 2011. The aim of this study is to investigate the energy consumption of palm methyl ester (PME) production in Thailand using a life cycle approach compared to other possible oil crops for biodiesel production including jatropha and coconut. The main contributors to the energy use are cultivation, oil production, transesterification and transportation. Taking into account only fossil fuel or petroleum inputs in the production cycle, the energy analysis provides results in favour of PME in Thailand. The net energy balance (NEB) and net energy ratio (NER) of PME and co-products are 100.84GJ/ha and 3.58, respectively. The NER of PME without co-products is 2.42, which is still higher than one indicating a favourable result. The results are important in selecting an appropriate feedstock for biodiesel production and this study will support policy makers in the energy sector to make informed decisions vis-à-vis promotion of oil palm plantation for biodiesel. This will also support the Thai government in its policy to promote the use of indigenous and renewable sources for transportation fuels. [Copyright &y& Elsevier]