Net Energy Balance Research Articles

Sleep patterns in relation to dietary patterns and cardio‐metabolic risk: An update from Drummond Pump Priming Award recipients

AbstractThis article provides an update on the project ‘Sleep patterns in relation to dietary patterns and cardio‐metabolic risk’, which received funding from the British Nutrition Foundation (BNF) Drummond Pump Priming Award. Studying the relationship between sleep, the biological clock, timing of eating and nutrition is part of a new research area termed chrono‐nutrition. With the help of the BNF award, a PhD project was set up to investigate the effects of sleep duration and quality on energy balance, dietary intake and quality, and cardio‐metabolic risk factors. The project included three studies: (1) a systematic review and meta‐analysis investigating whether partial sleep deprivation results in positive energy balance; (2) a cross‐sectional study exploring associations between energy balance, dietary intake and quality, chrono‐nutrition and cardio‐metabolic risk factors; and (3) a randomised controlled intervention feasibility study investigating whether sleep extension in participants with chronic mild sleep deprivation can improve energy balance, diet quality, body composition and cardio‐metabolic risk profile. The systematic review showed that partial sleep deprivation results in a net positive energy balance arising from a significantly higher energy intake of 385 kcal/day, with no compensatory effect on energy expenditure. Results from the cross‐sectional and randomised controlled feasibility studies are expected later this year. Overall, the project will help to establish whether sleep extension can be used in combination with existing weight management strategies to reduce the burden of obesity and metabolic dysregulation, which are major public health threats.

Organic Rankine Cycles (ORC) for mobile applications – Economic feasibility in different transportation sectors

Organic Rankine Cycles (ORC) offer a valuable alternative to recover waste heat from internal combustion engines (ICE) in transportation systems, leading to fuel energy savings and reduced emissions. Nevertheless, the additional weight of the ORC affects the net energy balance of the overall system and the ORC occupies additional volume that competes with vehicle transportation capacity. A lower income from delivered freight or passenger tickets will be therefore achieved. This work defines a benchmark for the economic feasibility of integrating an ORC into an ICE and the resulting economic impact of weight and volume in the transportation sector. It additionally investigates the current ORC situation on the market.The applied methodology defines a maximum allowable change of transport capacity caused by the integration of the ORC. The procedure is applied to a typical city bus, a truck of 40 t of payload capacity, a middle-size freight train (1000 t), an inland water vessel (Va RoRo, 2500 t) and ocean vessel (25,000 t). The results are compared with commercial ORC products.The findings of the present study are a theoretical and practical approach for the economic application of ORCs in the transportation sector. For maritime transportation, the situation appears highly favorable. For integration for trains and trucks appeared successful, but close to the limit line. For busses, a competitive integration requires a strong reduction in weight and volume.In future works, the potential for volume and mass reduction of the ORC has to be addressed together with the integration of an economic assessment for the ORC.

Modeling net energy balance of ethanol production from native warm season grasses

There has been an increasing interest in the use of perennial grasses as potential feedstock for ethanol production. The characteristics which make perennial grasses attractive for bioenergy feedstock development initiative are their high yield potential and the high contents of lignin and cellulose. The objective of the study is to model energy input and output and simulate Net Energy Value (NEV) of producing ethanol from native warm season grasses. According to simulated results, the mean NEV of ethanol production from native warm season grasses considered in the analysis was positive. Mean NEV for switchgrass and eastern gammagrass was higher compared to Indiangrass and big bluestem. Although the probability of having positive NEV is high, there is a risk of having negative energy balance under low output scenarios.

Advanced anaerobic digestion of municipal sludge using a novel and energy-efficient radio frequency pretreatment system

Microwave (MW) sludge pretreatment systems are usually limited to a frequency of 2.45 GHz and the heating frequency is constrained by commercially available hardware. Studies using MW heating at this frequency have reported negative net energy balance (output energy as methane minus input electrical energy). This necessitates further research into more efficient thermal pretreatment technologies. In this research, a novel and highly efficient radio frequency (RF) pretreatment system at a frequency of 13.56 MHz was designed, implemented, and tested for the first time. The system was custom-designed based on the dielectric characteristics of thickened waste activated sludge (TWAS) to achieve a very efficient and uniform heating system. The effects of three factors including pretreatment method (RF vs. MW), final temperature (60, 90 and 120 °C), and stationary (holding) time (0, 1 and 2 h) on sludge solubilization and performance of mesophilic batch anaerobic digestion were evaluated simultaneously. Energy measurements were also made to compare the efficiency of the custom-designed RF and conventional MW heating systems. The differences in sludge disintegration (solubilization) using the RF and MW pretreatment systems were negligible (P > 0.05). No statistically significant difference was also observed between the two pretreatment systems in terms of mesophilic biogas production rate and extent (P > 0.05). The energy efficiency of the RF pretreatment system was measured between 67.3 and 95.5% for the temperature range of 25–120 °C which was significantly higher than that of the MW system efficiency which varied from 37 to 43%. Overall, the average input energy of the RF system was less than half of the energy consumed during the operation of the MW system to achieve a same target temperature. Considering the results of this research, the RF heating at a frequency of 13.56 MHz is suggested as an effective and energy-efficient technique for thermal hydrolysis of TWAS.

Spectral problem for water flow glazings

Water flow glazings are characterized by a water chamber which transports the absorbed solar energy in the glazing. A multilayer water flow glazing comprises glass layers, Polyvinyl Butyral (PVB) layers, coatings, air gaps, and a water layer. Heat absorption from solar radiation depends on the spectral properties of each layer. Energy performance is governed by the optical and radiative properties of the layers. The refractive index and the extinction coefficient define the optical properties of a layer. The optical properties of the water layer are known from the scientific literature [1]. Transmittance and reflectance for every wavelength are measurements supplied by manufacturers and are readily available from the International Glazing Database (IGDB) as a function of wavelength at normal incidence. In this work, a net energy balance radiation model similar to Siegel [2] is used to solve the spectral problem. A matrix difference equation for a vector of dimension two with boundary conditions is stated to obtain the absorptances of each layer and each interface. The inputs of this set of equations are the transmissivity of each layer, and the transmittance and reflectances of each interface which are based on the refractive index and the extinction coefficient. When these values are not known, an inverse problem is solved to obtain the refractive index and the extinction coefficient of each layer for every wavelength from transmittance and reflectance measurements of the IGDB. For coatings, another inverse problem is formulated to obtain the properties of the coated interface using also transmittance and reflectance measurements of the coated glass pane and the substrate. The outputs of this work are the wavelength-averaged absorptances of each layer, which determine the fractions of the impinging radiation which is absorbed in each layer. The results constitute the inputs of the thermal problem of a water flow glazing.

Energy upcycle in anaerobic treatment: Ammonium, methane, and carbon dioxide reformation through a hybrid electrodeionization–solid oxide fuel cell system

To create possibilities for a more sustainable wastewater management, a novel system consisting of electrodeionization (EDI) and solid oxide fuel cells (SOFCs) is proposed in this study. This system is integrated with anaerobic digestion/landfills to capture energy from carbonaceous and nitrogenous pollutants. Both EDI and SOFCs showed good performances. EDI removed 95% and 76% ammonium-nitrogen (NH4+-N) from diluted (0.025M) to concentrated (0.5M) synthetic ammonium wastewaters, respectively, accompanied by hydrogen production. SOFCs converted the recovered fuels, biogas mixtures of methane and carbon dioxide, to electricity. Under the optimal conditions of EDI (3.0V applied voltage and 7.5mm internal electrode distance (IED), and SOFCs (750°C operating temperature), the system achieved 60% higher net energy output as compared to conventional systems. The estimated energy benefit of this proposed system showed that the net energy balance ratio is enhanced from 1.11 (existing system) to 1.75 (this study) for a local Hong Kong active landfill facility with 10.0gL−1 chemical oxygen demand (COD) and 0.21M NH4+-N. Additionally, an average of 80% inorganic ions (heavy metals and nutrient elements) can be removed from the raw landfill leachate by EDI cell. The results are successful demonstrations of the upgrades of anaerobic processes for energy extraction from wastewater streams.

Energy and environmental assessments of bioethanol production from Sri Kanji 1 cassava in Malaysia

According to the Malaysia’s biofuel policy, renewable fuels are crucial for energy sustainability in the transportation sector in the future. This study was aimed to evaluate the potential of bioethanol production from Sri Kanji 1 cassava in Malaysia in terms of energy efficiency and renewability, as well to estimate the potential greenhouse gas (GHG) emissions reduction in CO2 equivalent. Bioethanol production process from cassava includes cassava farming, ethanol production, and transportation in which the primary energy consumption was considered. The Net Energy Balance (NEB) and Net Energy Ratio (NER) of 25.68 MJ/L and 3.98, respectively, indicated that bioethanol production from Sri Kanji 1 cassava in Malaysia was energy efficient. From the environmental perspective, the GHG balance results revealed that the production and distribution of 1 L of Cassava Fuel Ethanol (CFE) could reduce GHG emissions by 73.2%. Although found promising in the present study, Sri Kanji 1 cassava as bioethanol feedstock should be further investigated by constructing an actual ethanol plant to obtain real life data.

Integrated Methane and Ethanol Production from Livestock Manure and Soybean Straw

Methane and ethanol were co-produced from different feedstock, including a mixture of dairy manure and soybean straw (DMS), a mixture of pig manure and soybean straw (PMS), and soybean straw alone (SS), after anaerobic digestion times of 30 and 60 days in mesophilic conditions. Digesting DMS for 60 days led to the highest methane yield of 115.3 g/kg dry raw feed; however, the lowest ethanol yield of 88 g/kg dry raw feed was observed. After 30 days, SS yielded the lowest methane levels (45.2 g/kg dry raw feed) but the highest ethanol levels (113.5 g/kg dry raw feed). Analysis of the net energy balance showed that the highest net energy balance, 6549 kJ/kg of dry raw feedstock, was achieved from the digestion of DMS for 60 days. Overall, both the type of feedstock and length of digestion time played important roles in the integrated processing of methane and ethanol from livestock manure and straw.

Assessment of micro-scale anaerobic digestion for management of urban organic waste: A case study in London, UK

This paper describes the analysis of an AD plant that is novel in that it is located in an urban environment, built on a micro-scale, fed on food and catering waste, and operates as a purposeful system. The plant was built in 2013 and continues to operate to date, processing urban food waste and generating biogas for use in a community café. The plant was monitored for a period of 319days during 2014, during which the operational parameters, biological stability and energy requirements of the plant were assessed. The plant processed 4574kg of food waste during this time, producing 1008m3 of biogas at average 60.6% methane. The results showed that the plant was capable of stable operation despite large fluctuations in the rate and type of feed. Another innovative aspect of the plant was that it was equipped with a pre-digester tank and automated feeding, which reduced the effect of feedstock variations on the digestion process. Towards the end of the testing period, a rise in the concentration of volatile fatty acids and ammonia was detected in the digestate, indicating biological instability, and this was successfully remedied by adding trace elements. The energy balance and coefficient of performance (COP) of the system were calculated, which concluded that the system used 49% less heat energy by being housed in a greenhouse, achieved a net positive energy balance and potential COP of 3.16 and 5.55 based on electrical and heat energy, respectively. Greenhouse gas emissions analysis concluded that the most important contribution of the plant to the mitigation of greenhouse gases was the avoidance of on-site fossil fuel use, followed by the diversion of food waste from landfill and that the plant could result in carbon reduction of 2.95kg CO2eq kWh−1 electricity production or 0.741kg CO2eq kg−1 waste treated.

Influence of conjugated linoleic acid and vitamin E on performance, energy metabolism, and change of fat depot mass in transitional dairy cows

The objective of this experiment was to determine the effects of conjugated linoleic acid (CLA) and vitamin E as well as their interaction on performance variables and lipomobilization during late pregnancy and early lactation (wk 6 antepartum until wk 10 postpartum). For this purpose, 59 pluriparous German Holstein cows were assigned to 4 dietary groups in a 2 × 2 design with the factors CLA and vitamin E at 2 levels. For this trial, we selected cows with a high body condition score because they are more likely to mobilize fat and consequently are at a higher risk of developing ketosis. Furthermore, concentrate proportions were adjusted to provoke ketosis. Lactation performance variables were analyzed in 3 periods (d 42 antepartum until calving, 1 to 21 d in milk, 22 to 70 d in milk). Dry matter intake and net energy intake were reduced in animals receiving CLA. Milk fat content was reduced in the CLA group compared with the control group (4.83 vs. 5.46% in period 2; 3.36 vs. 4.57% in period 3). In the vitamin E and the CLA + vitamin E groups, reduction of milk fat content was observed in period 3 (3.76 vs. 4.57% compared with the control group). Milk yield was not affected by treatment. β-Hydroxybutyrate concentrations and liver lipid contents were not influenced by CLA or vitamin E. Moreover, longitudinal changes of adipose tissue depot mass were not affected by dietary treatments. Results suggest that the effects CLA had on milk composition were compensated by an increased milk yield and a decreased dry matter intake. Reduced milk energy output in CLA-treated animals was compensated by a reduced dry matter intake. Therefore, the net energy balance was not affected by either treatment. Consequently, we found no group effect on the mobilization of adipose tissue.

Bioelectrochemical anaerobic sewage treatment technology for Arctic communities.

This study describes a novel wastewater treatment technology suitable for small remote northern communities. The technology is based on an enhanced biodegradation of organic carbon through a combination of anaerobic methanogenic and microbial electrochemical (bioelectrochemical) degradation processes leading to biomethane production. The microbial electrochemical degradation is achieved in a membraneless flow-through bioanode-biocathode setup operating at an applied voltage below the water electrolysis threshold. Laboratory wastewater treatment tests conducted through a broad range of mesophilic and psychrophilic temperatures (5-23°C) using synthetic wastewater showed a biochemical oxygen demand (BOD5) removal efficiency of 90-97% and an effluent BOD5 concentration as low as 7mgL-1. An electricity consumption of 0.6kWhkg-1 of chemical oxygen demand (COD) removed was observed. Low energy consumption coupled with enhanced methane production led to a net positive energy balance in the bioelectrochemical treatment system.

Estimativa do fluxo de calor no solo a partir da temperatura do solo em São Paulo, SP

O fluxo de calor no solo é um dos componentes do balanço de energia, que, junto com calor latente e sensível e os processos biológicos, é resultado da partição da energia líquida disponível. Esse índice geralmente é obtido a partir de medições com fluxímetros, termômetros de solo, ou ainda, estimado por satélites ambientais, segundo metodologias específicas. Neste trabalho, utilizaram-se medições de temperatura do solo a 0 e 20 cm de profundidade para calcular o fluxo de calor no solo por meio do método de DECICO (1967). As medições foram realizadas em uma área de Latossolo Vermelho-Amarelo no Parque Estadual Fontes do Ipiranga (PEFI), importante remanescente preservada da Mata Atlântica na Região Metropolitana de São Paulo, que dispõe de uma importante série histórica de dados climáticos. Os resultados indicam que o fluxo de calor médio é de 3,69 W m-2 ou 2,83% da energia líquida disponível, semelhante a áreas de Mata Atlântica e Floresta Amazônica.

Energetics and Water Requirement of a Commercial- Scale Sweet Sorghum Ethanol Production

This study quantifies the energy balance and water requirement for ethanol production from sweet sorghum. The energy balance assessment is important to verify if the system actually achieves a positive net energy balance, while inventory of water requirement provides primary approximation of the water economy of this alternative feedstock. The boundary of the assessment is from the production of the feedstock to the products’ end-use (cradle-to-grave). All the balances were based from a 30-M L yr-1capacity commercial bioethanol plant that operates for 270 d yr-1. The net energy balance of the system was computed by accounting the total energy consumed by the materials and processes in the boundary equated with the total energy produced through the products – power and biofuel. From the assessment, it was verified that the production gains a net energy equivalent to 475,621,789.51MJ yr-1 or 15.85 MJ L-1 of ethanol produced. Since the assessment assumed that a new bioethanol facility will be put up, the analysis included the energy invested during this pre-operational period, termed as “energy debt.” Construction of the whole facility expended a total of 1,127,076,244.75MJ energy or 37.57 MJ L-1 ethanol. However, because the system gains a net energy, a payback period for the energy invested was computed by dividing the total energy debt by the net energy gain. It was deduced that energy debt can be offset or paid back within 2.37 years of operation. Meanwhile, the total water economy in the construction of the bioethanol plant amounts to 960,453.44 m3. Likewise, the whole operation consumed a total of 12,368,904,260.86 L for a year’s operation, which is equivalent to 412.30 L water L-1 ethanol produced, or 19.45 L MJ-1, or 24,541.48 L T-1 cane processed.

Energy-efficient Systems for the Sensing and Separation of Mixed Polymers

Polymers are ubiquitous in modern manufactured products. The potential detrimental impacts of their end-of-life disposal have stimulated significant increases in recycling rates. Recyclate purity is paramount; however this must be achieved with a positive net energy balance. Existing technologies for identification and separation of polymers are often both expensive and energy intensive. This paper investigates Infrared (IR) imaging to extract information on thermal properties of various product polymers within a recycling line. An intelligent decision making support system is enabled using neural network based pattern recognition for automatic polymer identification and classification. Potential energy savings versus current technologies are discussed.

Erratum to: Life cycle assessment of integrated seawater agriculture in the Arabian (Persian) Gulf as a potential food and aviation biofuel resource

Prospective evaluation of the lifecycle impacts of aviation biofuel production in Abu Dhabi, UAE based on a production system that integrates aquaculture, saltwater agriculture, and mangrove silviculture, termed an Integrated Seawater Energy Agriculture System (ISEAS) in order to investigate its energetic and environmental potential compared to conventional fuels. We compare the hydroprocessed renewable jet fuel (HRJ) produced from ISEAS against fossil jet fuel using a life cycle assessment (LCA) methodology. Based on a detailed description of the production process, we use data from a wide-ranging literature review and experimental results from the specific location to make informed assumptions for the range of the process inputs and yields. We then analyze several process configuration scenarios with different ranges. ISEAS can produce aviation biofuels, electricity, and food while afforesting coastal desert land, acting as a long-term sink for carbon, minimizing freshwater consumption, and having beneficial land use impacts when compared to fossil jet fuel production. Based on a sensitivity analysis, we show that ISEAS HRJ emits 38 to 68% less greenhouse gases than fossil jet fuel and yields an overall positive net energy balance under all scenarios except one with an extensive use of desalinated water. ISEAS offers a promising pathway for integrating aquaculture and seawater agriculture in arid regions. It is essentially a process to sustainably augment aquaculture-based products by using its waste as a biofuel resource. Achieving positive emissions results depend critically on minimizing freshwater use, maximizing biomass yield and to a lesser extent the performance of biomass gasification.

The effects of partial sleep deprivation on energy balance: a systematic review and meta-analysis.

It is unknown whether short sleep duration causatively contributes to weight gain. Studies investigating effects of partial sleep deprivation (PSD) on energy balance components report conflicting findings. Our objective was to conduct a systematic review and meta-analysis of human intervention studies assessing the effects of PSD on energy intake (EI) and energy expenditure (EE). EMBASE, Medline, Cochrane CENTRAL, Web of Science and Scopus were searched. Differences in EI and total EE following PSD compared with a control condition were generated using the inverse variance method with random-effects models. Secondary outcomes included macronutrient distribution and resting metabolic rate. Heterogeneity was quantified with the I2-statistic. Seventeen studies (n=496) were eligible for inclusion in the systematic review, and 11 studies (n=172) provided sufficient data to be included in meta-analyses. EI was significantly increased by 385 kcal (95% confidence interval: 252, 517; P<0.00001) following PSD compared with the control condition. We found no significant change in total EE or resting metabolic rate as a result of PSD. The observed increase in EI was accompanied by significantly higher fat and lower protein intakes, but no effect on carbohydrate intake. The pooled effects of the studies with extractable data indicated that PSD resulted in increased EI with no effect on EE, leading to a net positive energy balance, which in the long term may contribute to weight gain.

Rough surfaces: Is the dark stuff just shadow?: “Who knows what evil lurks in the hearts of men? The shadow knows!”

Remote observations of the surfaces of airless planetary objects are fundamental to inferring the physical structure and compositional makeup of the surface material. A number of forward models have been developed to reproduce the photometric behavior of these surfaces, based on specific, assumed structural properties such as macroscopic roughness and associated shadowing. Most work of this type is applied to geometric albedos, which are affected by complicated effects near zero phase angle that represent only a tiny fraction of the net energy reflected by the object. Other applications include parameter fits to resolved portions of some planetary surface as viewed over a range of geometries. The spherical albedo of the entire object (when it can be determined) captures the net energy balance of the particle more robustly than the geometric albedo. In most treatments involving spherical albedos, spherical albedos and particle phase functions are often treated as if they are independent, neglecting the effects of roughness. In this paper we take a different approach. We note that whatever function captures the phase angle dependence of the brightness of a realistic rough, shadowed, flat surface element relative to that of a smooth granular surface of the same material, it is manifested directly in both the integral phase function and the spherical albedo of the object. We suggest that, where broad phase angle coverage is possible, spherical albedos may be easily corrected for the effects of shadowing using observed (or assumed) phase functions, and then modeled more robustly using smooth-surface regolith radiative transfer models without further imposed (forward-modeled) shadowing corrections. Our approach attributes observed “powerlaw” phase functions of various slope (and “linear” ranges of magnitude-vs.-phase angle) to shadowing, as have others, and goes in to suggest that regolith-model-based inferences of composition based on shadow-uncorrected spherical albedos overestimate the amount of absorbing material contained in the regolith.

Global warming potential and energy analysis of second generation ethanol production from rice straw in India

The environmental sustainability of cellulosic ethanol production from rice straw in India is conducted using life cycle assessment (LCA). Greenhouse gas (GHG) emissions, net energy ratio (NER) and net energy balance (NEB) are studied for ethanol production system using two diverse pretreatment technologies, i.e. dilute acid (DA) and steam explosion (SE) followed by separate hydrolysis and fermentation. 1ton of rice straw is the reference flow of study and 1MJ transportation fuel is the functional unit while comparing the results with gasoline. The inventory data is collected based on several experiments conducted at our pilot plant and is a novel contribution to country specific LCA. Using DA and SE, the ethanol yields from the processing of 1ton straw are 239 and 253L and life cycle GHG emissions are 292 and 288kgCO2eq./ton straw respectively. The results indicated that production of enzyme used in hydrolysis is the major contributor to GHG emissions in both DA (54%) and SE (57%) methods of ethanol production. The net energy input during the life cycle of ethanol is 1736 and 1377MJ/ton straw in DA and SE respectively. The major GHG emissions and energy benefits are obtained using lignin produced in the plant to generate electricity resulting in displacement of the coal based electricity. With a higher xylose recovery in the SE, it gives larger amount of ethanol and also generates more surplus electricity. Enzyme production and its use are identified as GHG emission and energy consumption hotspot in the ethanol production process. While comparing the results with gasoline, DA and SE resulted in a reduction of 77 and 89% GHG emissions and NER of 2.3 and 2.7 respectively. The E5 blending would reduce GHG emissions by 4.3% (DA) and 4.8% (SE) whereas; E20 blend would lead to a reduction of 17.4% (DA) and 18.8% (SE) respectively. Sensitivity analysis indicates that with every 12.5% increase in the price of rice straw from the base case, there is a 2.3% increase in GHG emissions and vice versa. 1FPU/g WIS increase during hydrolysis gives 2.9% increase in ethanol production, but at the same time there is an increase of 5% emissions from enzyme production. The results of the study conclude that cellulosic ethanol production technology in India is sustainable from GHG reduction and energy efficiency perspective.

Co-management of domestic wastewater and food waste: A life cycle comparison of alternative food waste diversion strategies

Food waste is increasingly viewed as a resource that should be diverted from landfills. This study used life cycle assessment to compare co-management of food waste and domestic wastewater using anaerobic membrane bioreactor (AnMBR) against conventional activated sludge (CAS) and high rate activated sludge (HRAS) with three disposal options for food waste: landfilling (LF), anaerobic digestion (AD), and composting (CP). Based on the net energy balance (NEB), AnMBR and HRAS/AD were the most attractive scenarios due to cogeneration of produced biogas. However, cogeneration negatively impacted carcinogenics, non-carcinogenics, and ozone depletion, illustrating unavoidable tradeoffs between energy recovery from biogas and environmental impacts. Fugitive emissions of methane severely increased global warming impacts of all scenarios except HRAS/AD with AnMBR particularly affected by effluent dissolved methane emissions. AnMBR was also most sensitive to food waste diversion participation, with 40% diversion necessary to achieve a positive NEB at the current state of development.

Prolonged sitting negatively affects the postprandial plasma triglyceride-lowering effect of acute exercise.

The interaction of prolonged sitting with physical exercise for maintaining health is unclear. We tested the hypothesis that prolonged siting would have a deleterious effect on postprandial plasma lipemia (PPL, postprandial plasma triglycerides) and reduce the ability of an acute exercise bout to attenuate PPL. Seven healthy young men performed three, 5-day interventions [days 1-5 (D1-D5)] in a randomized crossover design with >1 wk between interventions: 1) sitting > 14 h/day with hypercaloric energy balance (SH), 2) sitting >14 h/day with net energy balance (SB), and 3) active walking/standing with net energy balance (WB) and sitting 8.4 h/day. The first high-fat tolerance test (HFTT1) was performed on D3 following 2 days of respective interventions. On the evening of D4 subjects ran on a treadmill for 1 h at ~67% V̇o2max, followed by the second HFTT (HFTT2) on D5. Two days of prolonged sitting increased TG AUCI (i.e., incremental area under the curve for TG), irrespective of energy balance, compared with WB (27% in SH, P = 0.003 and 26% in SB, P = 0.046). Surprisingly, after 4 days of prolonged sitting (i.e.; SH and SB), the acute exercise on D4 failed to attenuate TG AUCI or increase relative fat oxidation in HFTT2, compared with HFTT1, regardless of energy balance. In conclusion, prolonged sitting over 2-4 days was sufficient to amplify PPL, which was not attenuated by acute exercise, regardless of energy balance. This underscores the importance of limiting sitting time even in people who have exercised.