• Energy Research

Bioelectrochemical systems like microbial fuel cells (MFCs) are quaint systems known to metamorphose the chemical energy of organic matter into electrical energy using catalytic activity of microorganisms. A novel continuous Auto Circulating Bio-Electrochemical Reactor (AutoCirBER) was developed to fulfil the gap of 'simple, inexpensive and compact design' that can continuously treat larger amount of organic wastewater at shorter residence time and without consuming external energy for liquid mixing. AutoCirBER eliminated the need for external agitation for liquid-mixing and therefore, energy requirements. AutoCirBER was operated in continuous-mode and hydraulic retention time was optimized. The reactor underwent performance check-up viz. COD removal, net power output, columbic efficiency, sludge generation and an attributional life cycle assessment (LCA) was also conducted. AutoCirBER was sustainable to run in continuous-mode and showed more than 90.4% of COD removal, and 59.55 W.h net annual energy recovery. Experimental LCA of AutoCirBER also displays its environmental feasibility in longer run.

Bioelectrochemical systems like microbial fuel cells (MFCs) are quaint systems known to metamorphose the chemical energy of organic matter into electrical energy using catalytic activity of microorganisms. A novel continuous Auto Circulating Bio-Electrochemical Reactor (AutoCirBER) was developed to fulfil the gap of 'simple, inexpensive and compact design' that can continuously treat larger amount of organic wastewater at shorter residence time and without consuming external energy for liquid mixing. AutoCirBER eliminated the need for external agitation for liquid-mixing and therefore, energy requirements. AutoCirBER was operated in continuous-mode and hydraulic retention time was optimized. The reactor underwent performance check-up viz. COD removal, net power output, columbic efficiency, sludge generation and an attributional life cycle assessment (LCA) was also conducted. AutoCirBER was sustainable to run in continuous-mode and showed more than 90.4% of COD removal, and 59.55 W.h net annual energy recovery. Experimental LCA of AutoCirBER also displays its environmental feasibility in longer run.

Abstract The present study intended to enhance the bioethanol production potential of wheat straw by reducing furfural and 5-hydroxymethylfurfural. The combination of 180 °C and 2% H2SO4 was optimized for pretreatment of wheat straw, which resulted significantly higher total soluble sugar. The maximum amount of furfural and HMF were observed when wheat straw pretreated at 180 to 220 °C, using 4% (v/v) dilute sulfuric acid. Amendment of pretreated acid hydrolysate using activated charcoal (5%, w/v) reduced up to 84.01% furfural and up to 76.42% HMF concentration in filtrate. The maximum ethanol yield of 5.29% (v/v) was obtained from charcoal amended acid hydrolysate, equivalent to 87.9% theoretical yield. Ethanol yield coefficient (Yps) was found to be 0.44 g ethanol g−1 sugar utilized. These results indicate that activated charcoal treated acid hydrolysate will be effective among the available technologies and could make lignocellulosic biomass-based ethanol production process economically viable by maximizing ethanol yield.

Abstract The present study intended to enhance the bioethanol production potential of wheat straw by reducing furfural and 5-hydroxymethylfurfural. The combination of 180 °C and 2% H2SO4 was optimized for pretreatment of wheat straw, which resulted significantly higher total soluble sugar. The maximum amount of furfural and HMF were observed when wheat straw pretreated at 180 to 220 °C, using 4% (v/v) dilute sulfuric acid. Amendment of pretreated acid hydrolysate using activated charcoal (5%, w/v) reduced up to 84.01% furfural and up to 76.42% HMF concentration in filtrate. The maximum ethanol yield of 5.29% (v/v) was obtained from charcoal amended acid hydrolysate, equivalent to 87.9% theoretical yield. Ethanol yield coefficient (Yps) was found to be 0.44 g ethanol g−1 sugar utilized. These results indicate that activated charcoal treated acid hydrolysate will be effective among the available technologies and could make lignocellulosic biomass-based ethanol production process economically viable by maximizing ethanol yield.

Grass biomethane is a sustainable transport biofuel. It can meet the 60% greenhouse gas saving requirements (as compared to the replaced fossil fuel) specified in the EU Renewable Energy Directive, if allowance is made for carbon sequestration, green electricity is used and the vehicle is optimized for gaseous biomethane. The issue in this paper is the effect of the digester type on the overall emissions savings. Examining three digestion configurations; dry continuous (DCAD), wet continuous (WCAD), and a two phase system (SLBR-UASB), it was found that the reactor type can result in a variation of 15% in emissions savings. The system that as modeled produced most biogas, and fuelled a vehicle most distance, the two phase system (SLBR-UASB), was the least sustainable due to biogas losses in the dry batch step. The system as modeled which produced the least biogas (DCAD) was the most sustainable as the parasitic demands on the system were least. Optimal reactor design for sustainability criteria should maximize biogas production, while minimizing biogas losses and parasitic demands.

Grass biomethane is a sustainable transport biofuel. It can meet the 60% greenhouse gas saving requirements (as compared to the replaced fossil fuel) specified in the EU Renewable Energy Directive, if allowance is made for carbon sequestration, green electricity is used and the vehicle is optimized for gaseous biomethane. The issue in this paper is the effect of the digester type on the overall emissions savings. Examining three digestion configurations; dry continuous (DCAD), wet continuous (WCAD), and a two phase system (SLBR-UASB), it was found that the reactor type can result in a variation of 15% in emissions savings. The system that as modeled produced most biogas, and fuelled a vehicle most distance, the two phase system (SLBR-UASB), was the least sustainable due to biogas losses in the dry batch step. The system as modeled which produced the least biogas (DCAD) was the most sustainable as the parasitic demands on the system were least. Optimal reactor design for sustainability criteria should maximize biogas production, while minimizing biogas losses and parasitic demands.

Biodiesel is an alternative, carbon-neutral fuel compared to fossil-based diesel, which can reduce greenhouse gas (GHGs) emissions. Biodiesel is a product of microorganisms, crop plants, and animal-based oil and has the potential to prosper as a sustainable and renewable energy source and tackle growing energy problems. Biodiesel has a similar composition and combustion properties to fossil diesel and thus can be directly used in internal combustion engines as an energy source at the commercial level. Since biodiesel produced using edible/non-edible crops raises concerns about food vs. fuel, high production cost, monocropping crisis, and unintended environmental effects, such as land utilization patterns, it is essential to explore new approaches, feedstock and technologies to advance the production of biodiesel and maintain its sustainability. Adopting bioengineering methods to produce biodiesel from various sources such as crop plants, yeast, algae, and plant-based waste is one of the recent technologies, which could act as a promising alternative for creating genuinely sustainable, technically feasible, and cost-competitive biodiesel. Advancements in genetic engineering have enhanced lipid production in cellulosic crops and it can be used for biodiesel generation. Bioengineering intervention to produce lipids/fat/oil (TGA) and further their chemical or enzymatic transesterification to accelerate biodiesel production has a great future. Additionally, the valorization of waste and adoption of the biorefinery concept for biodiesel production would make it eco-friendly, cost-effective, energy positive, sustainable and fit for commercialization. A life cycle assessment will not only provide a better understanding of the various approaches for biodiesel production and waste valorization in the biorefinery model to identify the best technique for the production of sustainable biodiesel, but also show a path to draw a new policy for the adoption and commercialization of biodiesel.