Energy Production in Irrigated, Intensively Cultured Plantations of Populus 'Tristis #1' and Jack Pine

Energy auditing of long-term conservation agriculture based irrigated intensive maize systems in semi-arid tropics of India

Modeling the point of use EROI and its implications for economic growth in China

Field experiment was conducted on baby corn (Zea mays L.) in sandy loam soil during the pre-kharif season of 2012 and 2013 at Varanasi to assess the effect of balanced fertilization (NPKS and Zn) on productivity, quality, energetics and soil health of baby corn. Results revealed that application of 125% RDF (187.5, 93.75, 75.0 kg NPK/ha) produced significantly higher yields of total baby cob yield with husk (9.55 tonnes/ha) and total baby corn yield without husk (2.15 tonnes/ha). Similarly, the higher nutrients (NPKS) and protein content in baby corn and green husk were recorded with application of 125% RDF. Among different levels of S and Zn, application of 50 kg S and 10 kg Zn/ha produced significantly higher yields of total baby cob with husk (9.38 and 9.24 tonnes/ha) and total baby corn without husk (2.15 and 2.10 tonnes/ha), respectively. Further, the crop fertilized with 50 kg S and 10 kg Zn/ha increased the nutrients (NPKSZn) and protein contents in babycorn and green husk but it was noted being on a par with application of 25 kg S and 5 kg Zn/ha. In terms of energetics, the higher values of energy inputs (20.71 x 103 MJ/ha), energy returns (226.98 x 103 MJ/ha), net energy returns (205.98 x 103 MJ/ha), energy use efficiency (10.80), energy productivity (0.454/kg/MJ), human profitability (65.20), energy productivity (9.80), energy intensiveness (0.354 MJ/Rupees), energy output efficiency (3.78 x 103 MJ/ha/day) and energy intensity in economic terms (3.82 MJ/Rupees) were recorded with application of 125% RDF and the lowest with 100% RDF. Similarly, application of 50 kg S and 10 kg Zn/ha gave the highest values of energy inputs (18.33 and 17.91 x 103 MJ/ha), energy returns (223.12 and 219.69 x 103 MJ/ha), net energy returns (203.31and 200.09 x 103 MJ/ha), energy use efficiency (11.25 and 11.19), energy productivity (0.473 and 0.471 kg/MJ), energy intensiveness (0.330 and 0.328 MJ/Rupees), energy output efficiency (3.72 and 3.66 x 103 MJ/ha/day), energy intensity in economic terms (3.71 and 3.67 MJ/Rupees), human energy profitability (64.09 and 63.11) and energy profitability (10.25 and 10.19), respectively as compared to its preceding doses. The highest actual loss of S and Zn were recorded with application of 125% RDF, 50 kg S and 10 kg Zn/ha whereas, the maximum positive balance of S and Zn were associated with 50 kg S and 10 kg Zn/ha, respectively.

Calculating systems-scale energy efficiency and net energy returns: A bottom-up matrix-based approach

Studies of the energy return on investment (EROI) for oil production generally rely on aggregated statistics for large regions or countries. In order to better understand the drivers of the energy productivity of oil production, we use a novel approach that applies a detailed field-level engineering model of oil and gas production to estimate energy requirements of drilling, producing, processing, and transporting crude oil. We examine 40 global oilfields, utilizing detailed data for each field from hundreds of technical and scientific data sources. Resulting net energy return (NER) ratios for studied oil fields range from ≈2 to ≈100 MJ crude oil produced per MJ of total fuels consumed. External energy return (EER) ratios, which compare energy produced to energy consumed from external sources, exceed 1000:1 for fields that are largely self-sufficient. The lowest energy returns are found to come from thermally-enhanced oil recovery technologies. Results are generally insensitive to reasonable ranges of assumptions explored in sensitivity analysis. Fields with very large associated gas production are sensitive to assumptions about surface fluids processing due to the shifts in energy consumed under different gas treatment configurations. This model does not currently include energy invested in building oilfield capital equipment (e.g., drilling rigs), nor does it include other indirect energy uses such as labor or services.

Declining production from conventional oil resources has initiated a global transition to unconventional oil, such as tar sands. Unconventional oil is generally harder to extract than conventional oil and is expected to have a (much) lower energy return on (energy) investment (EROI). Recently, there has been a surge in publications estimating the EROI of a number of different sources of oil, and others relating EROI to long-term economic growth, profitability and oil prices. The following points seem clear from a review of the literature: (i) the EROI of global oil production is roughly 17 and declining, while that for the USA is 11 and declining; (ii)the EROI of ultra-deep-water oil and oil sands is below 10; (iii) the relation between the EROI and the price of oil is inverse and exponential; (iv) as EROI declines below 10, a point is reached when the relation between EROI and price becomes highly nonlinear; and (v) the minimum oil price needed to increase the oil supply in the near term is at levels consistent with levels that have induced past economic recessions. From these points, I conclude that, as the EROI of the average barrel of oil declines, long-term economic growth will become harder to achieve and come at an increasingly higher financial, energetic and environmental cost.

Biomass was the principal energy source in preindustrial societies; their agriculture provided more energy than it required. Thus, the energy return on energy investment (EROEI) needed to be >1. Recent studies have indicated that this may not be the case for modern industrialized agrifood systems (AFSs). Although the green revolution radically improved agricultural yields, it came at the expense of increased energy inputs, mainly in the form of fossil fuels. AFSs relying on external energy pose a food security risk, an economic issue for agricultural producers, and an environmental issue for all. Previous EROEI studies investigated mainly certain groups of commodities, typically at the local or national level. Here, a comprehensive global analysis shows that current AFSs have a lower EROEI than previously estimated. Globally, EROEI has increased from 0.68 in 1995 to 0.91 in 2019. In low-income regions, AFSs are still energy sources, but their EROEI has declined with increasing wealth, reflecting the growing utilization of fossil fuels. AFSs of high-income regions are energy sinks, although their EROEI has improved. Food processing is responsible for 40% of the total energy use in the global AFS, notably larger than fertilizer, which accounts for 17%. More than half of the energy use in food processing is for livestock products that also require disproportionate energy input through their inefficient conversion of (human-edible) feed. Livestock products use 60% of energy inputs while delivering <20% of food calories.

This study examines the operational feasibility of six treatments to regenerate jack pine (Pinus banksiana Lamb.) naturally without fire following harvesting on clay soils in the southeastern boreal forest of Quebec. The experiment is a randomized complete block design. Techniques used were a final cutting in 1993 with manual on-site delimbing or roadside delimbing combined with three methods of soil scarification (WadellTM, La TaupeTM and a control) performed in the Spring of 1994 compared to an adjacent jack pine plantation established in 1994 after Wadell scarification. Seven growing seasons later, the present article compares stand composition, competing vegetation, regeneration and growth of jack pine between the different treatments as well as an adjacent plantation. Natural regeneration produced mixed stands with an adequate 52% average jack pine stocking. Roadside and on-site delimbing produced similar jack pine stocking on average. However, the plantation showed 83% stocking and better performance than natural regeneration in terms of height (2.48 m vs. 1.7 m for natural regeneration), diameter (41 mm vs. 22 mm for natural regeneration) and jack pine dominance. Therefore, if natural regeneration is desired, roadside delimbing is to be recommended since it provides sufficient seed and does avoid early jack pine growth reductions caused by slash. On clay soils, scarification seems to have been optional. Nevertheless, it slightly increased seedling growth and in this way, the treatment combining road-side delimbing and an extensive scarification can be an effective jack pine natural regeneration treatment.Key words: Pinus banksiana Lamb., natural regeneration, stocking coefficient, delimbing, scarification, boreal mixed wood, seedlings

I first came across Carey King when, out of the blue, he invited me to a special session of the annual meeting of the American Association for the Advancement of Science (the largest and most prestigious US scientific meeting) where he was developing a special session on energy return on investment (EROI). At that meeting and since, I have found Carey to be a refreshing new colleague, extremely intelligent, very knowledgeable about many diverse aspects of energy and other things, able to take criticism and to dish it out, and very ambitious, which is mostly a good thing. He is becoming a leader in thinking about EROI and its implications, and I am delighted to see him honored by Environmental Research Letters.

The heavy reliance of the livestock industry of the European Union (EU) on feed protein imports has initiated a transition to alternative protein sources such as grass proteins. Green biorefineries (which process grass into protein and other related bio‐products) are gaining interest in the EU as the EU searches for ways to cut its import of feed proteins, to reduce its reliance on fossil fuels, and to combat climate change. However, the vulnerability of green biorefineries to fossil energy constraints has not been studied. We estimated the energy conversion efficiencies (EE) and the energy return on investment (EROI) of bio‐products from standalone (SGBR) and integrated grass refinery (IGBR) systems using scenario and energy analysis. The base scenario assumes an SGBR that processes grass into protein, fiber, and brown juice. The three IGBR scenarios assume that grass is processed into protein, fiber, and biomethane (Scenario 1); into protein, fiber, heat, and electricity (Scenario 2); or into protein, fiber, heat, and biomethane (Scenario 3). We found that the EE of the IGBR (83%–85%) largely exceeded that of the SGBR (77%) in all cases. Energy returns on investment were lower for grass than for clover‐grass because of the high fertilizer needs of the former. The standard EROIs (EROIstd) for grass protein ranged from 1.6 to 5.4 over the various feedstocks and scenarios evaluated. The EROIstd decreased when the system boundary was expanded to the point of use (EROIpou), or when they were adjusted for quality (EROIqly). Other bioproducts from both SGBR and IGBR also had high EROIstd, and showed similar patterns to that of grass protein (i.e., EROIstd &gt; EROIpou &gt; EROIqly). Although Scenario 1 had a high EE relative to the base scenario, its heavy reliance on auxiliary energy inputs reduced the EROIs of its products. Our analysis showed the strong impacts of brown‐juice recycling in the energy performance of green biorefinery. It thus deserves close attention when designing and implementing a green biorefinery in a given region. With favorable economic conditions, green biorefineries could contribute to the reduction of food and energy insecurity in Europe in a sustainable way. © 2020 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Effects of edges on plant communities in a managed landscape in northern Wisconsin

Re-evaluation of energy return on investment (EROI) for China's natural gas imports using an integrative approach

A coupled model of global energy production and ERoEI applied to photovoltaic and wind, an estimation of net production

A wealth of data and information on the cultivation of perennial biomass crops has been collected, but direct comparisons between herbaceous and woody crops are rare. The main objective of this research was to compare the biomass yield, the energy balance and the biomass quality of six perennial bioenergy crops: Populus spp., Robinia pseudoacacia, Salix spp., Arundo donax, Miscanthus × giganteus, and Panicum virgatum, grown in two marginal environments. For giant reed and switchgrass, two levels of nitrogen fertilization were applied annually (0–100 kg ha−1). Nitrogen fertilization did not affect biomass or energy production of giant reed; thus, it significantly reduced the energy return on investment (EROI) (from 73 to 27). In switchgrass, nitrogen fertilization significantly increased biomass production and the capacity of this crop to respond to water availability, making it a favorable option when only biomass production is a target. Net energy gain (NEG) was higher for herbaceous crops than for woody crops. In Casale,EROIcalculated for poplar and willow (7, on average) was significantly lower than that of the other crops (14, on average). In Gariga, the highestEROIwas calculated for miscanthus (98), followed by nonfertilized giant reed and switchgrass (82 and 73, respectively). Growing degree days10during the cropping season had no effect on biomass production in any of the studied species, although water availability from May to August was a major factor affecting biomass yield in herbaceous crops. Overall, herbaceous crops had the highest ranking for bioenergy production due to their high biomass yield, high net energy gain (NEG), and biomass quality that renders them suitable to both biochemical and thermochemical conversion. Miscanthus in particular had the highestEROIin both locations (16 and 98, in Casale and Gariga), while giant reed had the highestNEGon the silty‐loam soil of Gariga.

Agriculture is the largest sector of Pakistan’s economy, contributing almost 22% to the GDP and employing almost 45% of the total labor force. The two largest food crops, wheat and rice, contribute 3.1% and 1.4% to the GDP, respectively. The objective of this research was to calculate the energy return on investment (EROI) of these crops on a national scale from 1999 to 2009 to understand the size of various energy inputs and to discuss their contributions to the energy output. Energy inputs accounted for within the cropping systems included seed, fertilizer, pesticide, human labor, tractor diesel, irrigation pump electricity and diesel, the transport of fertilizer and pesticide, and the embodied energy of tractors and irrigation pumps. The largest per-hectare energy inputs to wheat were nitrogen fertilizer (52.6%), seed (17.9%), and tractor diesel (9.1%). For rice, the largest per-hectare energy inputs were nitrogen fertilizer (32%), tube well diesel (19.8%), and pesticide (17.6%). The EROI of wheat showed a gradual downward trend between 2000 and 2006 of 21.3%. The trend was erratic thereafter. Overall, it ranged from 2.7 to 3.4 with an average of 2.9 over the 11-year study period. The overall trend was fairly consistent compared to that of rice which ranged between 3.1 and 4.9, and averaged 3.9. Rice’s EROI dipped sharply in 2002, was erratic, and remained below four until 2007. It rose sharply after that. As energy inputs increased, wheat outputs increased, but rice outputs decreased slightly. Rice responded to inputs with greater output and an increase in EROI. The same was not true for wheat, which showed little change in EROI in the face of increasing inputs. This suggests that additional investments of energy in rice production are not improving yields but for wheat, these investments are still generating benefits. The analysis shows quantitatively how fossil energy is a key driver of the Pakistani agricultural system as it traces direct and indirect energy inputs to two major food crops.