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The current status and challenges associated with the production and utilization of cellulosic ethanol in Korea are reviewed in this paper. Cellulosic ethanol has emerged as a promising option for mitigating Korea's CO(2) emissions and enhancing its energy security. Korea's limited biomass resources is the most critical barrier to achieving its implementation targets for cellulosic ethanol. Efforts to identify new suitable biomass resources for cellulosic ethanol production are ongoing and intensive. Aquatic biomasses including macroalgae and plantation wastes collected in the Southeast Asia region have been found to have great potential as feedstocks for the production of cellulosic ethanol. R&D explorations into the development of technologies that can convert biomass materials to ethanol more efficiently also are underway. It is expected that cellulosic ethanol will be in supply from 2020 and that, by 2030, its use will have effectively reduced Korea's total gasoline consumption by 10%.

Abstract The proposed innovative approach identifies a new application for biomass. Bioenergy is used to drive a desalination unit which produces water for irrigating energy crops. Biomass is cultivated on artificial soil made by a mixture of local soil and organic compost from MSW (Municipal Solid Wastes). This agro-energy farm scheme aims at rescuing arid lands near to the sea. The study defines a techno-economic compromise among energy crops, biomass generator, desalination unit and irrigation system, considering an arid area (10 ha) of Tenerife as reference case study. A small experimental activity (100 m 2 ) has also been performed on site. A Sweet Sorghum cultivation, a bioenergy generator, a reverse osmosis plant and drip irrigation system have been chosen. The main result of the study is that the possibility of retaining some 14–20% surplus (in terms of biomass or energy or water) exists. The system is energetically feasible: rescued land can be doubled in approximately 4 yr. This approach is applicable to many Mediterranean coastal areas, as well as other similar situations elsewhere.

Bioenergy is considered a sustainable substitute to fossil-fuel resources and the development of a prudent combination of renewable and innovative conversion technologies are essential for the valorization and effective conversion of biowaste to value-added commodities. Here, a negative pressure-induced carbonization process was proposed for the valorization of lignin-enriched biowaste precursor to bio-oil and environmental materials (biochar) at various temperatures. The high heating values (HHV) of the as-prepared biochars from the lignin enriched precursor under negative pressure (low-medium vacuum) were within 25.9-31.5 MJ/kg, which matched satisfactorily to the commercial charcoal. Whereas, the bio-oils produced from the lignin enriched precursor under vacuum conditions was a blend of complex aromatic and straight-chain hydro-carbons, including aldehyde, ketone, phenol, and furans, exhibiting ability as potential heating-oil with HHV within 21.2-28.2 MJ/kg. Moreover, the biochars produced under vacuum environments at higher temperature showed greater stability (22.5-35.9%) than those produced under N2 atmosphere.

Anode with good electrocatalytic capabilities is more specifically required to reduce the ohimic losses during microbial fuel cell (MFC) operation. Highly conductive polymers viz., Polyaniline (PANi) and Polyaniline/Carbon nanotube (PANi/CNT) composite were prepared by in situ oxidative chemical polymerization method. Anodes were fabricated independently by coating PANi and CNT/PANi composites on the surface of SSM. The fabricated electrodes were evaluated as anode against stainless steel mess (SSM) as cathode during MFC operation. Maximum bioelectricity generation was observed in SSM-PANi/CNT-anode with power density of 48 mW/m2 and COD removal efficiency of 80% compared with SSM-PANi-anode (38 mW/m2; 65%) and SSM-anode (28 mW/m2; 58%). Bioelectrochemical characterization of the electrode materials using cyclic voltammetry and electrochemical impedance spectroscopy showed high electrocatalytic activity of PANi/CNT composite electrode. The study concluded the efficiency of PANi/CNT composite electrodes as bioanode in operation of MFCs towards achieving increased bioelectricity production along with wastewater treatment.

Cylindrical graphite microbial fuel cell (MFC) configuration designed by eliminating distinct casing and membrane was evaluated for bioelectrogenesis and treatment of real-field wastewaters. Both petroleum refinery wastewater (PRW) and Labanah whey wastewater (LW) were used as substrates, and investigated for electricity generation and organic removal under batch mode operation. PRW showed higher bioelectricity generation (current and power generation of 3.35mA and 1.12mW at 100Ω) compared to LW (3.2mA and 1.02mW). On the contrary, higher substrate degradation efficiency was achieved using LW (72.76%) compared to PRW (45.06%). Superior function of MFC operation in terms of volumetric power density (PRW, 28.27W/m3; LW, 23.23W/m3) suggesting the feasibility of using these wastewaters for bioelectricity generation. Large sources of wastewater that generating in the Middle-East countries have potential to produce renewable energy from the treatment, which helps for the sustainable wastewater management and simultaneous renewable energy production.

Sustainable aviation fuels (SAFs) can contribute reduce greenhouse gas emissions compared to conventional fuel. With the increasing SAFs demand, various generations of resources have been shifted from the 1st generation (oil crops), the 2nd generation (agricultural waste), to the 3rd generation (microalgae). Microalgae are the most suitable feedstock for jet biofuel production than other resources because of their productivity and capability to capture carbon dioxide. However, microalgae-based biofuel has a limitation of high freezing point. Recently, a jet biofuel derived from Euglena wax ester has been paying attention due to its low freezing point. Challenges still remain to enhance production yields in both upstream and downstream processes. Studies on downstream processes as well as techno-economic analysis on biofuel production using Euglena are highly limited to date. Economic aspects for the biofuel production will be ensured via valorization of industrial byproducts such as food wastes.

Implementing a circular economy aimed at reusing resources is becoming increasingly important for industry. Microalgae fit within a circular economy by being able to bioremediate nutrient waste and as a source of biomass for several commercial applications. Here, we report a novel validation of a circular economy concept using microalgae at a relevant industrial scale with a new two-phase process. During the first phase biomass was grown autotrophically, biomass was then concentrated using membrane technology for the second phase where mixotrophic conditions were applied to boost growth further. Microalgae cultures were able to grow (13.8 g/L), uptake and bioremediate nutrients (Nitrogen > 134 mg/L/day) from an anaerobic digestion side-stream (digestate), obtaining high quality microalgae biomass (>45% protein content) suitable for use as animal feed, closing the circular economy loop for industrial applications.

Although recent research has demonstrated that waste orange peel (WOP) is a potentially valuable resource that can be transformed into high value products, heat generation, biomethanisation and composting might be considered the most feasible alternatives in terms of yield. This study revealed that WOP can be successfully valorised through combustion. However, a previous drying step, which generates hazardous wastewater, is required and harmful NOx are emitted with the flue gases. In contrast, a high yield of renewable methane (280LSTPCH4/kg added COD, chemical oxygen demand) and an organic amendment can be obtained through the thermophilic biomethanisation of WOP following the removal of valuable essential oils from the peel. Co-composting of WOP combined at different proportions (17-83%) with the organic fraction of municipal solid waste (OFMSW) was also demonstrated to be suitable. Moreover, a 37% reduction in odour generation was observed in co-composting of WOP compared to single composting of OFMSW.