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Power-to-methane (PtM) is a prospective solution to the mismatching between the supply and consumption of renewable energy resources (RES) by converting renewable power into methane. However, the continuous fluctuation of RES causes the PtM system to deviate from the design condition in the vast majority of cases, and thus it is significantly vital to study the operating characteristics of the PtM system under off-design conditions. This paper proposes a comprehensive investigation framework from design to off-design steps for the performance improvement of a PtM system combining solid oxide electrolysis cell with methanation reactor, and solar energy is selected as renewable energy input. Firstly, the system with the total exergy efficiency (ηEX,tot) of 11.83% and levelized cost of exergy (LCOE) of 150.76 $/MWh is selected as the optimal design condition based on the homogeneous assessment from both thermodynamic and economic aspects, by means of Non-dominated sorting genetic algorithm-II. Then, based on the optimal design point, the off-design performances are quantitatively investigated under varying solar radiation and key operating parameters, in terms of synthetic natural gas (SNG) yield and ηEX,tot. The results indicate that with the increment in solar radiation, the SNG yield rises, while the ηEX,tot increases first and then decreases. Finally, the multi-objective optimization based on the Artificial Neural Network models is implemented for the system under off-design conditions to acquire the best trade-off between hourly SNG yield and ηEX,tot. The off-design optimization solutions reveal that the hourly optimal SNG yield is located in the range of 275.06–946.53 kW, achieving a total annual SNG yield of 1697 MWh/y, and the hourly optimal ηEX,tot mainly varies in the range of 10.40–11.40%.

Power-to-methane (PtM) is a prospective solution to the mismatching between the supply and consumption of renewable energy resources (RES) by converting renewable power into methane. However, the continuous fluctuation of RES causes the PtM system to deviate from the design condition in the vast majority of cases, and thus it is significantly vital to study the operating characteristics of the PtM system under off-design conditions. This paper proposes a comprehensive investigation framework from design to off-design steps for the performance improvement of a PtM system combining solid oxide electrolysis cell with methanation reactor, and solar energy is selected as renewable energy input. Firstly, the system with the total exergy efficiency (ηEX,tot) of 11.83% and levelized cost of exergy (LCOE) of 150.76 $/MWh is selected as the optimal design condition based on the homogeneous assessment from both thermodynamic and economic aspects, by means of Non-dominated sorting genetic algorithm-II. Then, based on the optimal design point, the off-design performances are quantitatively investigated under varying solar radiation and key operating parameters, in terms of synthetic natural gas (SNG) yield and ηEX,tot. The results indicate that with the increment in solar radiation, the SNG yield rises, while the ηEX,tot increases first and then decreases. Finally, the multi-objective optimization based on the Artificial Neural Network models is implemented for the system under off-design conditions to acquire the best trade-off between hourly SNG yield and ηEX,tot. The off-design optimization solutions reveal that the hourly optimal SNG yield is located in the range of 275.06–946.53 kW, achieving a total annual SNG yield of 1697 MWh/y, and the hourly optimal ηEX,tot mainly varies in the range of 10.40–11.40%.

AbstractThe wood pellet market is booming in Europe. The EU 2020 policy targets for renewable energy sources and greenhouse gas (GHG) emissions reduction are among the main drivers. The aim of this analysis is to map current European national wood pellet demand and supplies, to provide a comprehensive overview of major market types and prices, and to discuss the future outlook in light of raw material supply. Approximately 650 pellet plants produced more than 10 million tonnes of pellets in 2009 in Europe. Total European consumption was about 9.8 million tonnes, of which some 9.2 million tonnes is within the EU‐27, representing a modest 0.2% of Gross Energy Consumption (75 EJ level in 2008). The prices of most pellet types are increasing. While most markets of non‐industrial pellets are largely self‐sufficient, industrial pellet markets depend on the import of wood pellets from outside the EU‐27. Industrial pellet markets are relatively mature, compared to non‐industrial ones, because of their advanced storage facilities and long‐term price‐setting. However, industrial pellet markets are unstable, depending mainly on the establishment or the abolishment of public support schemes.Following our scenarios, additional 2020 demand for woody biomass varies from 105 million tonnes, based on market forecasts for pellets in the energy sector and a reference growth of the forest sector, to 305 million tonnes, based on maximum demand in energy and transport sectors and a rapid growth of the forest sector. Additional supply of woody biomass may vary from 45 million tonnes from increased harvest levels to 400 million tonnes after the recovery of slash via altered forest management, the recovery of waste wood via recycling, and the establishment of woody energy plantations in the future. Any short‐term shortages within the EU‐27 may be bridged via imports from nearby regions such as north west Russia or overseas. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd

AbstractThe wood pellet market is booming in Europe. The EU 2020 policy targets for renewable energy sources and greenhouse gas (GHG) emissions reduction are among the main drivers. The aim of this analysis is to map current European national wood pellet demand and supplies, to provide a comprehensive overview of major market types and prices, and to discuss the future outlook in light of raw material supply. Approximately 650 pellet plants produced more than 10 million tonnes of pellets in 2009 in Europe. Total European consumption was about 9.8 million tonnes, of which some 9.2 million tonnes is within the EU‐27, representing a modest 0.2% of Gross Energy Consumption (75 EJ level in 2008). The prices of most pellet types are increasing. While most markets of non‐industrial pellets are largely self‐sufficient, industrial pellet markets depend on the import of wood pellets from outside the EU‐27. Industrial pellet markets are relatively mature, compared to non‐industrial ones, because of their advanced storage facilities and long‐term price‐setting. However, industrial pellet markets are unstable, depending mainly on the establishment or the abolishment of public support schemes.Following our scenarios, additional 2020 demand for woody biomass varies from 105 million tonnes, based on market forecasts for pellets in the energy sector and a reference growth of the forest sector, to 305 million tonnes, based on maximum demand in energy and transport sectors and a rapid growth of the forest sector. Additional supply of woody biomass may vary from 45 million tonnes from increased harvest levels to 400 million tonnes after the recovery of slash via altered forest management, the recovery of waste wood via recycling, and the establishment of woody energy plantations in the future. Any short‐term shortages within the EU‐27 may be bridged via imports from nearby regions such as north west Russia or overseas. © 2011 Society of Chemical Industry and John Wiley & Sons, Ltd

Abstract Global changes in temperature will likely change energy use and electricity production capacity. Considering the relationship between climate change and energy resource use, changes in temperature and the frequency and intensity of extreme events will affect how much energy is produced and consumed. The green economy and green growth are located at the heart of the fight against climate change in creating sustainable development. This paper considers the multidirectional relations between climate change, energy resources, and sustainable development including the perspective of a green economy via a technoeconomic analysis. A link among energy resources, climate changes and sustainable development has been displayed via a technoeconomic analysis in the case study, which was focused on taking into consideration the needs of the hydroponic units, the product selling price, the electricity price of the wind farm (WF), and at the same time the energy demand, under a nexus approach. Via the technoeconomic analysis, it was proven that moving on to smaller investments of 2 MWs is more efficient compared to larger projects e.g. 18 MWs, however, this cannot be considered immediately as the preferred solution since it is always a matter of impact on the local society.

Abstract Global changes in temperature will likely change energy use and electricity production capacity. Considering the relationship between climate change and energy resource use, changes in temperature and the frequency and intensity of extreme events will affect how much energy is produced and consumed. The green economy and green growth are located at the heart of the fight against climate change in creating sustainable development. This paper considers the multidirectional relations between climate change, energy resources, and sustainable development including the perspective of a green economy via a technoeconomic analysis. A link among energy resources, climate changes and sustainable development has been displayed via a technoeconomic analysis in the case study, which was focused on taking into consideration the needs of the hydroponic units, the product selling price, the electricity price of the wind farm (WF), and at the same time the energy demand, under a nexus approach. Via the technoeconomic analysis, it was proven that moving on to smaller investments of 2 MWs is more efficient compared to larger projects e.g. 18 MWs, however, this cannot be considered immediately as the preferred solution since it is always a matter of impact on the local society.