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COVID-19 pandemic has brought tremendous environmental burden due to huge amount of medical wastes (about 54,000 t/d as of November 22, 2020), including face mask, gloves, clothes, goggles, and sanitizer/disinfectant containers. A proper waste management is urgently required to mitigate the spread of the disease, minimize the environmental impacts, and take their potential advantages for further utilization. This work provides a prospective review on the possible thermochemical treatments for those COVID-19 related medical wastes (CMW), as well as their possible conversion to fuels. The characteristics of each waste are initially analyzed and described, especially their potential as energy source. It is clear that most of CMWs are dominated by plastic polymers. Thermochemical processes, including incineration, torrefaction, pyrolysis, and gasification, are reviewed in terms of applicability for CMW. In addition, the mechanical treatment of CMW into sanitized refuse-derived fuel (SRDF) is also discussed as the preliminary stage before thermochemical conversion. In terms of material flexibility, incineration is practically applicable for all types of CMW, although it has the highest potential to emit the largest amount of CO2 and other harmful gasses. Furthermore, gasification and pyrolysis are considered promising in terms of energy conversion efficiency and environmental impacts. On the other hand, carbonization faces several technical problems following thermal degradation due to insufficient operating temperature.

Abstract This paper characterized the wood pellet and torrefied wood pellet fuel as compared to coal for 100 MW co-firing power generation plant. There were five experiments to characterise the chemical and physical properties of coal, wood pellet and torrefied wood pellet namely moisture analysis, Thermo gravimetric Analyser (TGA), Bomb Calorimeter, Organic Elemental Analyser and Scanning Electron Microscope (SEM). The moisture analysis result from moisture analyser and TGA shows that the moisture content of torrefied wood pellet is lower than wood pellet at 6.760% and 3.629%. Moreover, the volatile matter, hydrogen and nitrogen content of torrefied wood pellet is lower than wood pellet at 65.20%, 5.993% and 0.4078% correspondingly. The calorific value, fixed carbon content, ash and sulphur also increase in torrefied wood pellet at 20.68 MJ/kg, 28.85%, 2.321% and 0.1656% respectively. In general, torrefaction improve the fuel properties of wood pellet similar to coal. The 100 MW direct co-firing power plant provides less capital investment, operation and maintenance cost for low rate co-firing ratio. However, there is economic challenges for high rate co-firing substation of torrefied wood pellets.

AbstractOil palm empty fruit bunches (EFB) are currently poorly utilized residue from palm oil processing but considered to be a potential feedstock for power generation. This study focuses on the combination of the hydrothermal (HT) conversion and the water leaching to produce low-potassium biofuel in order to reduce the slagging and fouling potential of the EFB. Combination of HT process at 180°C and the water leaching not only reduced the ash content of the biomass but also reduced the potassium and chlorine contents, indicating the effectiveness of this combination to produce clean fuel. The total of 92% reduction of potassium can be obtained, while ash content can be significantly reduced from 4.9% to 0.9% wt. The potassium balance for HT process at 180°C followed by the water leaching is also presented in this study. By calculating the metal oxide ratio in the ash, several slagging/fouling indices can be determined. The slagging and fouling tendency of EFB is improved after HT followed by the leaching process, lowering the tendency of biomass to harm the furnace.

Abstract This study proposes a use of Data Envelopment Analysis (DEA) for environmental assessment. All organizations in private and public sectors produce not only desirable (good) but also undesirable (bad) outputs as a result of their economic activities. The proposed use of DEA determines the level of unified (operational and environmental) efficiency of all the organizations. A contribution of this study is that it explores how to measure not only RTS (Returns to Scale) on desirable outputs but also a new concept regarding “DTS: Damages to Scale” (corresponding to RTS for undesirable outputs). This study discusses how to measure RTS under natural disposability and DTS under managerial disposability by DEA. The measurement of RTS and DTS is formulated by incorporating “Strong Complementary Slackness Conditions (SCSCs)”. As a result, this study can handle an occurrence of multiple reference sets and multiple projections in the RTS/DTS measurement. The incorporation of SCSCs makes it possible both to restrict DEA multipliers in a specific range without any prior information and to identify all possible efficient organizations as a reference set. Using the unique capabilities of SCSCs, this study discusses the use of DEA environmental assessment by exploring how to classify the type of RTS/DTS with SCSCs. Such analytical capabilities are essential, but not previously explored in DEA environmental assessment for energy industries. As an illustrative example, this study applies the proposed approach for the performance evaluation of Japanese manufacturing industries. This study finds that these firms need to introduce technology innovation to reduce an amount of greenhouse gases and wastes. The empirical result confirms the importance of measuring RTS/DTS in DEA environmental assessment.

Abstract In this contribution a particular attention is being given to the strategic objective for the establishment of a North Africa (NA) countries cooperation on water and clean energy superhighway as the solution to regional energy challenges, water shortages, climate change and other environmental problems arising from the current fossil-fuel heavy global energy paradigm. Advanced and technical know-how and resources of Japan, through the Sahara Solar Breeder (SSB) project, can facilitate to achieve sustainable development in the region, cooperation to accelerate and expand its research activity with ambitious quantitative targets for solutions between the growing water crisis in NA and energy resources (fossil and renewables energies (RE)). With global energy demand set to rise significantly over the next 15 years, there will be a pressing need for fresh investment in new output capacity across the entire water/energy supply chain. It is still believed and emphasized that Photovoltaic (PV) will be a significant contributor within a portfolio of energy sources in the coming 10–20 years and that SSB is providing science and technology that are poised to play a transformative role in providing clean and sustainable water/energy for the whole world. Japan's energy/water innovative strategy for NA is encouraging since problems cannot be solved by one country alone hence local, regional and global cooperation is crucial.

Abstract This paper studies how the vertical structure of the electricity industry affects the social welfare when the incumbent has a cost advantage in generation relative to the entrants. The model consists of a generation sector and a transmission sector. In the generation sector the incumbent and entrants compete in a Cournot fashion taking as given the access charge to the transmission network set in advance by the regulator to maximize the social welfare. Two vertical structures, integration and separation , are considered. Under vertical separation the transmission network is established as an organization independent of every generator, whereas under vertical integration it is a part of the incumbent's organization. The optimal vertical structure is shown to depend on the number of entrants. If the number of entrants is smaller than a certain threshold, vertical separation is superior in welfare to vertical integration, and vice versa. This is because the choice of vertical structure produces a trade-off in the effects on competition promotion and production efficiency. If a break-even constraint is imposed in the transmission sector, however, vertical integration is shown to be always superior in welfare.

Biodiesel is defined as domestic renewable energy resource, which can be derived from natural oils through the transesterification. The implementation of biodiesel is essential due to the energy depletion crisis and the impact on exacerbating environment caused by rapid consumption of conventional diesel. Waste cooking oil (WCO) was used as the raw material to produce biodiesel in order to reduce wastes polluting the environment. This paper studies the technical potential of WCO biodiesel to be used as an alternative fuel for microturbine. The ASTM D6751 and ASTM D2881 standards were selected as references to evaluate the compatibility with distillate to be used as a microturbine fuel. The performance and emission tests were conducted employing a 30 kW microturbine, without any modification, using biodiesel and distillate blends up to maximum of 20% biodiesel mixing ratio. It was found that the thermal efficiency peaked at 20% biodiesel blend with distillate, despite the fact that biodiesel had a lower calorific value and a higher fuel consumption. The emission test results showed reduction of CO emission by increasing the WCO biodiesel mixing ratio, while NOx emission was dependent on the exhaust gas temperature. In conclusion, biodiesel derived from WCO has the potential to substitute distillate in the microturbine application.

A mangrove ecosystem is an important option in Ecosystem based Disaster Risk Reduction (Eco-DRR). The effectiveness of an artificial mangrove landfill in reducing tidal amplitudes was studied by performing a coupled numerical model that simulated wave propagation and soil consolidation. The constructed model simulated the propagation of tide over an artificial landfill that was subjected to land subsidence, sea-level rise, vegetation growth, and sediment deposition. A case study analysis confirmed that the tidal amplitudes are reduced if the initial elevation of the landfill is appropriately considered to achieve an equilibrium state of the landfill over its lifetime. Sediment deposition may be the only dependable source to sustain the surface elevation of a mangrove with relative sea-level rise. Sediment deposition is important to promote vegetation growth, which in turn contributes to sedimentation by enhancing a tranquil hydrodynamic environment. An insufficient initial elevation of the landfill will result in less effective protection against tidal propagation after it substantially subsides.