How does technology pathway choice influence economic viability and environmental impacts of lignocellulosic biorefineries?

Background: The need for liquid fuels in the transportation sector is increasing, and it is essential to develop industrially sustainable processes that simultaneously address the tri-fold sustainability metrics of technological feasibility, economic viability, and environmental impacts. Biorefineries based on lignocellulosic feedstocks could yield high-value products such as ethyl acetate, dodecane, ethylene, and hexane. This work focuses on assessing biochemical and biomass to electricity platforms for conversion of Banagrass and Energycane into valuable fuels and chemicals using the tri-fold sustainability metrics. Results: The production cost of various products produced from Banagrass was $1.19/kg ethanol,$1.00/kg ethyl acetate, $3.01/kg dodecane (jet fuel equivalent),$2.34/kg ethylene and $0.32/kW-h electricity. The production cost of different products using Energycane as a feedstock was$1.31/kg ethanol, $1.11/kg ethyl acetate,$3.35/kg dodecane, and $2.62/kg ethylene. The sensitivity analysis revealed that the price of the main product, feedstock cost and cost of ethanol affected the profitability the overall process. Banagrass yielded 11% higher ethanol compared to Energycane, which could be attributed to the differences in the composition of these lignocellulosic biomass sources. Acidification potential was highest when ethylene was produced at the rate of 2.56 × 10−2 and 1.71 × 10−2 kg SO2 eq. for Banagrass and Energycane, respectively. Ethanol production from Banagrass and Energycane resulted in a global warming potential of − 12.3 and − 40.0 g CO2 eq./kg ethanol. Conclusions: Utilizing hexoses and pentoses from Banagrass to produce ethyl acetate was the most economical scenario with a payback period of 11.2 years and an ROI of 8.93%, respectively. Electricity production was the most unprofitable scenario with an ROI of − 29.6% using Banagrass/Energycane as a feedstock that could be attributed to high feedstock moisture content. Producing ethylene or dodecane from either of the feedstocks was not economical. The moisture content and composition of biomasses affected overall economics of the various pathways studied. Producing ethanol and ethyl acetate from Energycane had a global warming potential of − 3.01 kg CO2 eq./kg ethyl acetate

Fixed Path Pull-In/Pushback Trajectories for Airliner Ground Transport

The process of ground movement of airplanes about an airport is currently accomplished with a combination of engine thrust and ground vehicles. Minimization of on-ground fuel usage of airlines and reduction of ground support equipment hazards are desirable goals for airlines and airports. Fuel economy, pollution and noise as well as safety improvements are sought by a variety of technologies and operational approaches. In this research, an investigation is conducted into the range of potential paths for pulling airliners into their destination gates and pushing them back for engine start on departure through fixed path nose gear tracks. The feasibility of fixed paths is analyzed for this application and improved trajectories are identified. A kinematic model is developed to generate the trajectory of Main Landing Gear, wing and tail tips of an aircraft. Benefits and risks of system integration also discussed

Updates on the pretreatment of lignocellulosic feedstocks for bioenergy production–a review

Lignocellulosic biomass is the most abundant renewable energy bioresources available today. Due to its recalcitrant structure, lignocellulosic feedstocks cannot be directly converted into fermentable sugars. Thus, an additional step known as the pretreatment is needed for efficient enzyme hydrolysis for the release of sugars. Various pretreatment technologies have been developed and examined for different biomass feedstocks. One of the major concerns of pretreatments is the degradation of sugars and formation of inhibitors during pretreatment. The inhibitor formation affects in the following steps after pretreatments such as enzymatic hydrolysis and fermentation for the release of different bioenergy products. The sugar degradation and formation of inhibitors depend on the types and conditions of pretreatment and types of biomass. This review covers the structure of lignocellulose, followed by the factors affecting pretreatment and challenges of pretreatment. This review further discusses diverse types of pretreatment technologies and different applications of pretreatment for producing biogas, biohydrogen, ethanol, and butanol

ADULT ONSET HENOCH: SCHONLEIN PURPURA – AN UNUSUAL PRESENTATION

  Henoch–Schonlein purpura (HSP) is a common leukocytoclastic vasculitis seen in children. However, it is uncommon in adults. HSP is characterized by the classic tetrad of non-thrombocytopenic palpable purpura, arthritis or arthralgias, gastrointestinal, and renal involvement. We report a rare case of adult onset HSP with multi-organ involvement. Early recognition of multi-organ involvement is very important, especially in adults

Artificial neural network–genetic algorithm-based optimization of biodiesel production from Simarouba glauca

A transesterification reaction was carried out employing an oil of paradise kernel (Simarouba glauca), a non-edible source for producing Simarouba glauca methyl ester (SGME) or biodiesel. In this study, the effects of three variables – reaction temperature, oil-to-alcohol ratio and reaction time – were studied and optimized using response surface methodology (RSM) and an artificial neural network (ANN) on the free fatty acid (FFA) level. Formation of methyl esters due to a reduction in FFA was observed in gas chromatography–mass spectroscopy (GC–MS) analysis. It was inferred that optimum conditions such as an oil-to-alcohol ratio of 1:6.22, temperature of 67.25 and duration of 20 h produce a better yield of biodiesel with FFA of 0.765 ± 0.92%. The fuel properties of paradise oil meet the requirements for biodiesel, by Indian standards. The results indicate that the model is in substantial agreement with current research, and simarouba oil can be considered a potential oil source for biodiesel production

Optimization of surfactant addition in cellulosic ethanol process using integrated techno-economic and life cycle assessment for bioprocess design

Surfactants have been demonstrated to be effective in increasing the cellulase enzyme efficacy and overall enzymatic hydrolysis efficiency. However, the impact of the surfactant addition on the economic viability and environmental impacts of the bioethanol process has not been well-investigated. The objective of this study was to determine the economic and the environmental impacts of using five surfactant types—polyethylene glycol (PEG) 3000, PEG4000, PEG6000, PEG8000, and Tween80—at various concentrations (8%, 5%, 2%, 1%, 0.75%, 0.5%, 0.25%, and 0% (w/w)) during enzymatic hydrolysis and fermentation of pretreated Banagrass. We used an integrated techno-economic and life cycle assesment to guide the selection of optimal surfactant concentration in the bioethanol process. A surfactant concentration of >2% negatively affects the profitability of ethanol, even when there is a statistically significant increase in glucose and ethanol titers. Based on the overall performance indicators for final ethanol, economic viability and environmental impacts, the addition of PEG6000 at 2% (w/w) were determined to be the optimal option. Glucose and ethanol concentrations of 119.2 ± 5.4 g/L and 55.0 ± 5.8 g/L, respectively, with an 81.5% cellulose conversion rate, were observed for 2% (w/w) PEG6000. Techno-economic and life cycle analysis indicated that 2% w/w PEG6000 addition resulted in ROI of 3.29% and had reduced the global warming potential by 6 g CO2/MJ ethanol produced

Effect of solids loading on ethanol production: Experimental, Economic and Environmental analysis

This study explores the effect of high-solids loading for a fed batch enzymatic hydrolysis and fermentation. The solids loading considered was 19%, 30% and 45% using wheat straw and corn stover as a feedstock. Based on the experimental results, techno-economic analysis and life cycle assessments were performed. The experimental results showed that 205±25.8 g/L glucose could be obtained from corn stover at 45% solids loading after 96h which when fermented yielded 115.9±6.37 g/L ethanol after 60h of fermentation. Techno-economic analysis showed that corn stover at 45% loading yielded the highest ROI at 8% with a payback period less than 12 years. Similarly, the global warming potential was lowest for corn stover at 45% loading at -37.8 gCO2 eq./MJ ethanol produced

What is the level of incentivisation required for biomethane upgrading technologies with carbon capture and reuse?

This paper documents a techno-economic assessment of biomethane feedstocks from urban, rural, and coastal settings. Additionally, the effect of three upgrading technologies was investigated, ranging from commercialised systems (water scrubbing) to more advanced systems: power to gas systems employing hydrogen to capture CO2; and microalgae cultivation utilising CO2 in biogas. In total, nine scenarios were investigated based on a combination of the three feedstock groups and the three upgrading technologies. The levelized cost of energy and the incentive required to allow financial sustainability were assessed. The assessment showed that water scrubbing was the cheapest upgrading method. The optimum scenario was the combination of urban based feedstock (food waste) with water scrubbing upgrading costing 87€/MWh, equivalent to 87c/L diesel equivalent. The incentive required was 0.13 €/m3 (or per L of diesel equivalent), however if power to gas was used to upgrade, an incentive of 0.40 €/m3 was required. This was expected as food waste attracts a gate fee. Rural-based plants (using slurries and grasses) are expected to provide the majority of the resource however, for this to become a reality incentive in the range 0.86–1.03 €/m3 are required

Are electrofuels a sustainable transport fuel? Analysis of the effect of controls on carbon, curtailment, and cost of hydrogen

Variable renewable electricity (VRE) decarbonises the electricity grid, but its intermittency leads to variations in price, carbon intensity, and curtailment over time. This has led to interest in utilising difficult to manage electricity to produce electrofuels (such as hydrogen via water electrolysis) for transport. The vast majority of the environmental impact of electrofuels is contained in the electricity they consume however, only consuming otherwise curtailed electricity (produced when supply exceeds demand) leads to prohibitively expensive hydrogen due to low run hours. Using a model which bids for wholesale electricity, two operational strategies (controls) aimed at increasing sustainability without requiring policy changes were tested in electricity system models of 40–60% renewable electricity penetration. (1) Bid price control set a maximum price the plant will pay for electricity. (2) Wind forecast control dictated that the plant may only run when a minimum forecast VRE production is met. It was shown that sourcing electricity at times of low cost or high forecast wind power can lead to more decarbonised hydrogen production (up to 56% more) at a lower cost (up to 57% less). When economically optimised (minimising levelised costs) the bid price control reduced the carbon intensity of the electrofuel produced by 5–25%, and the wind forecast control by 14–38%, compared to the grid average. Both controls demonstrated a high proclivity to utilising otherwise curtailed electricity and can be said to aid grid balancing. The bid price control also greatly reduced the average cost of electricity to the plant. The positive impacts increased with renewables penetration, and significant synergies between economic and environmentally conscious operation of the plants were noted. The operational strategies tested in this paper allow for transport fuels to be produced from grid electricity, without exacerbating the mismatch of supply and demand. Future decentralised quasi-storage using these operating strategies may economically produce transport fuel, and aid grid balancing

The combined role of policy and incentives in promoting cost efficient decarbonisation of energy: a case study for biomethane

The levelized cost of energy of biomethane from food waste was assessed at 87 €/MWh, (87 c/L diesel equiv.). Allowing for gate fees the incentive required for financial viability was 0.13 €/m3 (13 €/MWh). For context, various successful renewable energy policies were analysed across the EU including photovoltaics and biogas in Germany and electric vehicles in Norway. The schemes were compared with an incentive applied (or required) per tCO2 avoided. For Ireland, this study predicts that biomethane needs a financial subsidy of less than 180 €/tCO2 avoided, while most successful EU systems offer incentivisation levels less than 260 €/tCO2 avoided. In terms of incentives per tCO2 avoided Electric Vehicles (EV) stand out. When including all incentives such as grants and avoided parking costs, EVs can receive a sixteen-fold higher incentive as compared to biomethane based on tCO2 emissions avoided. The rationale for this high incentive and supporting policy is based on the requirement to initiate a new infrastructure that would not otherwise happen without intervention of a government incentivising decarbonised transport and clean air. Biomethane as a transport fuel requires a very significant change in infrastructure, including the provision of compressed natural gas service stations and natural gas vehicles. Initially (as for other successful renewable energy systems) larger incentives would be required to allow initiation of the industry, but these subsidies can be reduced over time. Biomethane as a transport fuel offers similar rewards as for electric vehicles, decarbonised transport and clean air along with energy security, renewable energy, indigenous jobs and supporting greening of agriculture