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Abstract For biomass/waste fueled power plants, stricter regulations require a further reduction of the negative impacts on the environment caused by the release of pollutants and withdrawal of fresh water externally. Flue gas quench (FGQ) is playing an important role in biomass or waste fueled combined heat and power (CHP) plants, as it can link the flue gas (FG) cleaning, energy recovery and wastewater treatment. Enhancing water evaporation can benefit the concentrating of pollutant in the quench water; however, when FG condenser (FGC) is not in use, it results in a large consumption of fresh water. In order to deeply understand the operation of FGQ, a mathematic model was developed and validated against the measurements. Based on simulation results key parameters affecting FGQ have been identified, such as the flow rate and temperature of recycling water and the moisture content of FG. A guideline about how to reduce the discharge of wastewater to the external and the withdrawal of external water can be proposed. The mathematic model was also implemented into an ASPEN Plus model about a CHP plant to assess the impacts of FGQ on CHP. Results show that when the FGC was running, increasing the flow rate and decreasing the temperature of recycling water can result in a lower total energy efficiency.

Abstract Cites have been identified as one key arena to meet future sustainability challenges. However, if cites are to be part of the transition it must become possible to confirm results of ongoing actions. By the introduction information and communication technologies, it has become easier to collect performance parameters from the built environment, thereby enable more detailed evaluation. The aim of this paper is therefore to examine the potential and limitation of using dynamic and high resolution meter data for evaluation of energy consumption in buildings and households. The novelty of this approach is that dynamic and high resolution meter data can increase the level of detail in evaluation results and ease detection of deviations in the structures performance. However, most benefits are found from the occupant perspective, as more detailed evaluation information enable better inclusion of this stakeholder group. Furthermore this study has shown that the commonly used indicator energy use per heated floor area is an insufficient communication tool when taking holistic approach to building energy evaluation. Limitation to full use of dynamic and high resolution meter data have been identified to data collection and management, preservation of personal integrity and incentives to react on the given evaluation information.

Abstract Biogas upgrading to synthetic natural gas (SNG) is a viable and appealing route for power-to-gas because it combines waste management with the use of the surplus electricity that might arise in energy systems having a considerable share of renewable energy sources in their production mix. In this work, the exergo-economic performance of a biogas upgrading process through integrated electrolysis and methanation is assessed in connection with the current market status to test which conditions could make the proposed option economically viable. Two different configurations, which differ mainly for the operating pressure of the electrolyser, are compared. The exergy efficiencies are high (>80%) and exergo-economic costs of the produced bio-SNG in the two analyzed configurations are 5.62 and 4.87 c€/kWhexergy, for low- and high-pressure respectively. Lower values would be required for the bio-SNG to compete with fossil natural gas. We show how both the input electricity price and the capacity factor have a substantial impact on the economic sustainability of the process. Eventually, the monetary exploitation of the oxygen produced by electrolysis and the participation to the emission trading scheme could contribute further to improve the economic attractiveness of the process.

More than 61% of the total population of Nepal has no access to electricity. The majority is poor and live in rural areas. In recent years, rural electrification has had high priority in government policies, and micro hydro and solar PV have been the most commonly adopted off-grid technologies. The financial mix in the off-grid rural electrification is generally characterized by subsidy, equity and credit. In this paper, we analyze how rural electrification has been funded and the impact of subsidy policies on the renewable energy market, focusing on the projects implemented under the ‘subsidy policy 2000’. Our study is based on official data obtained from authorities in Nepal and a survey carried out among private supply and installation companies, NGOs and financial institutions. The study shows that awareness levels in adopting RE-technologies and willingness of people to access and pay for electricity have increased significantly. However, there is a huge financial gap between the cost of electrification and the affordability. Bridging this gap is a crucial issue that needs to be addressed for the smooth expansion of rural electrification in the country.

Abstract The prior goal for a pulp and paper mill is to achieve a chemical recovery system with high availability and good reliability. It is also important that the heat recovery system produces sufficient process heat for the heat-demanding processes in the mill. Black liquor gasification promises to be a future alternative or a complement to the conventional Tomlinson recovery boilers in the pulp industry. Black liquor gasification should offer several advantages from both a chemical recovery and an energy point of view. The gasification process produces a combustible gas which can be used for steam and power generation in many ways. Several studies have shown that the power output from a heat and power cycle integrated with black liquor gasification has potential to get a higher energy efficiency than today's heat recovery technology. Especially with pressurized gasification and a gas-turbine-based cogeneration system, the power output will be significantly improved. However, the gas turbine is very sensitive to corrosive elements. The gas cleaning equipment in the gasification system must therefore have a high removal efficiency and a high reliability. The ambition is to keep the gasification capacity constant during the year, but the fuel consumption for the gas turbine increases at low ambient temperatures. The seasonal variation will cause the gas turbine to operate at partial load and, consequently, there will be a decrease in the gas turbine efficiency. An alternative combined cycle with high power efficiency is given by a hybrid plant in which the gas turbine is fired with natural gas while the fuel gas from the pressurized gasifier is used as a supplementary fuel for the Rankine cycle. A major advantage of the hybrid system is the use of a high purity fuel gas in the gas turbine. The system also allows for variations in pulp capacity which is difficult in an integrated gasification combined cycle (IGCC). This study compares the effect of using an IGCC system and a hybrid combined plant instead of a conventional recovery system. The results indicate a potential to double the power output if the conventional system is replaced by an IGCC system. A hybrid combined cycle system has also a higher net power efficiency than the conventional recovery system. Furthermore, the hybrid system can make the mill self-supporting on power and allows an increase in the heat consumption.

In this work, current information about the contamination of ground- and surface-water resources by arsenic from geogenic sources in Latin America is presented together with possible emerging mitigation solutions. The problem is of the same order of magnitude as other world regions, such as SE Asia, but it is often not described in English. Despite the studies undertaken by numerous local researchers, and the identification of proven treatment methods for the specific water conditions encountered, no technologies have been commercialized due to a current lack of funding and technical assistance. Emerging, low-cost technologies to mitigate the problem of arsenic in drinking water resources that are suitable for rural and urban areas lacking centralized water supplies have been evaluated. The technologies generally use simple and low-cost equipment that can easily be handled and maintained by the local population. Experiences comprise (i) coagulation/filtration with iron and aluminum salts, scaled-down for small community- and household-scale-applications, (ii) adsorption techniques using low-cost arsenic sorbents, such as geological materials (clays, laterites, soils, limestones), natural organic-based sorbents (natural biomass), and synthetic materials. TiO(2)-heterogeneous photocatalysis and zerovalent iron, especially using nanoscale particles, appear to be promising emergent technologies. Another promising innovative method for rural communities is the use of constructed wetlands using native perennial plants for arsenic rhizofiltration. Small-scale simple reverse osmosis equipment (which can be powered by wind or solar energy) that is suitable for small communities can also be utilized. The individual benefits of the different methods have been evaluated in terms of (i) size of the treatment device, (ii) arsenic concentration and distribution of species, chemical composition and grade of mineralization in the raw water, (iii) guidelines for the remaining As concentration, (iv) economical constrains, (v) complexity of installation and maintenance, and infrastructure constraints (e.g. electricity needs).

Greenhouse gas (GHG) accounting with respect to two categories of methane recovery and oxidation activities (coal bed or coal mine methane recovery and landfill gas (LFG) recovery) within the Clean Development Mechanism (CDM) is analysed. It is found that baseline methodologies approved by the CDM Executive Board apply systematically inconsistent assumptions concerning the global warming impact of carbon dioxide emissions from the oxidation of methane. One important implication of the results is that applying the baseline methodologies approved for project activities involving LFG recovery will lead to overestimation of the net GHG abatement effect of such CDM project activities.

Increasing the current low level of access to electricity in developing countries is important for economic development and poverty eradication. Encouraging the involvement of new actors for implem ...

Ineffective waste management that involves dumping of waste in landfills may degrade valuable land resources and emit methane gas (CH4), a more potent greenhouse gas than carbon dioxide (CO2). The incineration of waste also emits polluted chemicals such as dioxin and particle. Therefore, from a solid waste management perspective, both landfilling and incineration practices pose challenges to the development of a green and sustainable future. Waste-to-energy (WtE) has become a promising strategy catering to these issues because the utilisation of waste reduces the amount of landfilled waste (overcoming land resource issues) while increasing renewable energy production. The goal of this paper is to evaluate the energy and carbon reduction potential in Malaysia for various WtE strategies for municipal solid waste (MSW). The material properties of the MSW, its energy conversion potential and subsequent greenhouse gases (GHG) emissions are analysed based on the chemical compositions and biogenic carbon fractions of the waste. The GHG emission reduction potential is also calculated by considering fossil fuel displacement and CH4 avoidance from landfilling. In this paper, five different scenarios are analysed with results indicating a integration of landfill gas (LFG) recovery systems and waste incinerator as the major and minor WtE strategies shows the highest economical benefit with optimal GHG mitigation and energy potential. Sensitivity analysis on the effect of moisture content of MSW towards energy potential and GHG emissions are performed. These evaluations of WtE strategies provides valuable insights for policy decision in MSW management practices with cost effective, energy benefit, environmental protection.