Research

3369 KiB

Open AccessArticle

The Optimal Dispatch of a Power System Containing Virtual Power Plants under Fog and Haze Weather

by Yajing Gao, Huaxin Cheng, Jing Zhu, Haifeng Liang and Peng Li

Sustainability 2016, 8(1), 71; https://doi.org/10.3390/su8010071 - 13 Jan 2016

Cited by 17 | Viewed by 6116

With the growing influence of fog and haze (F-H) weather and the rapid development of distributed energy resources (DERs) and smart grids, the concept of the virtual power plant (VPP) employed in this study would help to solve the dispatch problem caused by [...] Read more.

With the growing influence of fog and haze (F-H) weather and the rapid development of distributed energy resources (DERs) and smart grids, the concept of the virtual power plant (VPP) employed in this study would help to solve the dispatch problem caused by multiple DERs connected to the power grid. The effects of F-H weather on photovoltaic output forecast, load forecast and power system dispatch are discussed according to real case data. The wavelet neural network (WNN) model was employed to predict photovoltaic output and load, considering F-H weather, based on the idea of “similar days of F-H”. The multi-objective optimal dispatch model of a power system adopted in this paper contains several VPPs and conventional power plants, under F-H weather, and the mixed integer linear programming (MILP) and the Yalmip toolbox of MATLAB were adopted to solve the dispatch model. The analysis of the results from a case study proves the validity and feasibility of the model and the algorithms. Full article

(This article belongs to the Special Issue Energy Conversion System Analysis)

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2193 KiB

Open AccessArticle

Design and Assessment of an IGCC Concept with CO₂ Capture for the Co-Generation of Electricity and Substitute Natural Gas

by Timo Blumberg, Max Sorgenfrei and George Tsatsaronis

Sustainability 2015, 7(12), 16213-16225; https://doi.org/10.3390/su71215811 - 04 Dec 2015

Cited by 12 | Viewed by 5836

Abstract

The focus of this work is on the modeling and the thermodynamic evaluation of an integrated gasification combined cycle (IGCC) for the co-production of electricity and substitute natural gas (SNG). At first, an IGCC with CO₂ capture for electricity generation is analyzed. [...] Read more.

The focus of this work is on the modeling and the thermodynamic evaluation of an integrated gasification combined cycle (IGCC) for the co-production of electricity and substitute natural gas (SNG). At first, an IGCC with CO₂ capture for electricity generation is analyzed. Coal-derived syngas is conditioned in a water gas shift unit (WGS), and cleaned in an acid gas removal system including carbon capture. Eventually, the conditioned syngas is fed to a combined cycle. A second case refers to a complete conversion of syngas to SNG in an integrated commercial methanation unit (TREMP™ process, Haldor Topsøe, Kgs. Lyngby, Denmark). Due to the exothermic reaction, a gas recycling and intercooling stages are necessary to avoid catalyst damage. Based on a state-of-the-art IGCC plant, an optimal integration of the synthetic process considering off-design behavior was determined. The raw syngas production remains constant in both cases, while one shift reactor in combination with a bypass is used to provide an adequate H₂/CO-ratio for the methanation unit. Electricity has to be purchased from the grid in order to cover the internal consumption when producing SNG. The resulting heat and power distributions of both cases are discussed. Full article

(This article belongs to the Special Issue Energy Conversion System Analysis)

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1597 KiB

Open AccessArticle

Improving the Environmental Sustainability of Flash Geothermal Power Plants—A Case Study

by Lorenzo Bruscoli, Daniele Fiaschi, Giampaolo Manfrida and Duccio Tempesti

Sustainability 2015, 7(11), 15262-15283; https://doi.org/10.3390/su71115262 - 18 Nov 2015

Cited by 10 | Viewed by 7395

Abstract

The sustainability of geothermal energy production is analyzed with reference to a production plant located in a specific area (Monte Amiata, Italy). Four solutions combining a flash power plant with an Organic Rankine Cycle in a hybrid configuration are analyzed in terms of [...] Read more.

The sustainability of geothermal energy production is analyzed with reference to a production plant located in a specific area (Monte Amiata, Italy). Four solutions combining a flash power plant with an Organic Rankine Cycle in a hybrid configuration are analyzed in terms of production of electricity, exergy balance and emissions level (CO₂, H₂S, Hg). The different solutions correspond to increasing environmental performance, and for the most advanced case achieve near-zero emissions (complete reinjection of the natural resource, including incondensable gases). The results show that this can be achieved at the price of a progressive reduction of electrical productivity. Full article

(This article belongs to the Special Issue Energy Conversion System Analysis)

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1255 KiB

Open AccessArticle

Energy Efficiency Evaluation and Economic Feasibility Analysis of a Geothermal Heating and Cooling System with a Vapor-Compression Chiller System

by Muharrem Imal, Koray Yılmaz and Ahmet Pınarbaşı

Sustainability 2015, 7(9), 12926-12946; https://doi.org/10.3390/su70912926 - 22 Sep 2015

Cited by 12 | Viewed by 6321

Abstract

Increasing attention has been given to energy utilization in Turkey. In this report, we present an energy efficiency evaluation and economic feasibility analysis of a geothermal heating and cooling system (GSHP) and a mechanical compression water chiller system (ACHP) to improve the energy [...] Read more.

Increasing attention has been given to energy utilization in Turkey. In this report, we present an energy efficiency evaluation and economic feasibility analysis of a geothermal heating and cooling system (GSHP) and a mechanical compression water chiller system (ACHP) to improve the energy utilization efﬁciency and reduce the primary energy demand for industrial use. Analyses of a mechanical water chiller unit, GSW 180, and geothermal heating and cooling system, EAR 431 SK, were conducted in experimental working areas of the office buildings in a cigarette factory in Mersin, Turkey. The heating and cooling loads of the cigarette factory building were calculated, and actual thermal data were collected and analyzed. To calculate these loads, the cooling load temperature difference method was used. It was concluded that the geothermal heating and cooling system was more useful and productive and provides substantial economic beneﬁts. Full article

(This article belongs to the Special Issue Energy Conversion System Analysis)

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1115 KiB

Open AccessArticle

Optimal Sizing of a Hybrid Grid-Connected Photovoltaic–Wind–Biomass Power System

by Arnau González, Jordi-Roger Riba and Antoni Rius

Sustainability 2015, 7(9), 12787-12806; https://doi.org/10.3390/su70912787 - 18 Sep 2015

Cited by 64 | Viewed by 8963

Abstract

Hybrid renewable energy systems (HRES) are a trendy alternative to enhance the renewable energy deployment worldwide. They effectively take advantage of scalability and flexibility of these energy sources, since combining two or more allows counteracting the weaknesses of a stochastic renewable energy source [...] Read more.

Hybrid renewable energy systems (HRES) are a trendy alternative to enhance the renewable energy deployment worldwide. They effectively take advantage of scalability and flexibility of these energy sources, since combining two or more allows counteracting the weaknesses of a stochastic renewable energy source with the strengths of another or with the predictability of a non-renewable energy source. This work presents an optimization methodology for minimum life cycle cost of a HRES based on solar photovoltaic, wind and biomass power. Biomass power seeks to take advantage of locally available forest wood biomass in the form of wood chips to provide energy in periods when the PV and wind power generated are not enough to match the existing demand. The results show that a HRES combining the selected three sources of renewable energy could be installed in a rural township of about 1300 dwellings with an up-front investment of US $7.4 million, with a total life cycle cost of slightly more than US $30 million. Such a system would have benefits in terms of energy autonomy and environment quality improvement, as well as in term of job opportunity creation. Full article

(This article belongs to the Special Issue Energy Conversion System Analysis)

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936 KiB

Open AccessArticle

Assessing Rare Metal Availability Challenges for Solar Energy Technologies

by Leena Grandell and Mikael Höök

Sustainability 2015, 7(9), 11818-11837; https://doi.org/10.3390/su70911818 - 26 Aug 2015

Cited by 52 | Viewed by 12925

Abstract

Solar energy is commonly seen as a future energy source with significant potential. Ruthenium, gallium, indium and several other rare elements are common and vital components of many solar energy technologies, including dye-sensitized solar cells, CIGS cells and various artificial photosynthesis approaches. This [...] Read more.

Solar energy is commonly seen as a future energy source with significant potential. Ruthenium, gallium, indium and several other rare elements are common and vital components of many solar energy technologies, including dye-sensitized solar cells, CIGS cells and various artificial photosynthesis approaches. This study surveys solar energy technologies and their reliance on rare metals such as indium, gallium, and ruthenium. Several of these rare materials do not occur as primary ores, and are found as byproducts associated with primary base metal ores. This will have an impact on future production trends and the availability for various applications. In addition, the geological reserves of many vital metals are scarce and severely limit the potential of certain solar energy technologies. It is the conclusion of this study that certain solar energy concepts are unrealistic in terms of achieving TW scales. Full article

(This article belongs to the Special Issue Energy Conversion System Analysis)

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561 KiB

Open AccessArticle

Thermoeconomic Analysis of Biodiesel Production from Used Cooking Oils

by Emilio Font de Mora, César Torres and Antonio Valero

Sustainability 2015, 7(5), 6321-6335; https://doi.org/10.3390/su7056321 - 22 May 2015

Cited by 18 | Viewed by 8083

Abstract

Biodiesel from used cooking oil (UCO) is one of the most sustainable solutions to replace conventional fossil fuels in the transport sector. It can achieve greenhouse gas savings up to 88% and at the same time reducing the disposal of a polluting waste. [...] Read more.

Biodiesel from used cooking oil (UCO) is one of the most sustainable solutions to replace conventional fossil fuels in the transport sector. It can achieve greenhouse gas savings up to 88% and at the same time reducing the disposal of a polluting waste. In addition, it does not provoke potential negative impacts that conventional biofuels may eventually cause linked to the use of arable land. For this reason, most policy frameworks favor its consumption. This is the case of the EU policy that double-counters the use of residue and waste use to achieve the renewable energy target in the transport sector. According to different sources, biodiesel produced from UCO could replace around 1.5%–1.8% of the EU-27 diesel consumption. This paper presents an in-depth thermoeconomic analysis of the UCO biodiesel life cycle to understand its cost formation process. It calculates the ExROI value (exergy return on investment) and renewability factor, and it demonstrates that thermoeconomics is a useful tool to assess life cycles of renewable energy systems. It also shows that UCO life cycle biodiesel production is more sustainable than biodiesel produced from vegetable oils. Full article

(This article belongs to the Special Issue Energy Conversion System Analysis)

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2346 KiB

Open AccessArticle

The Relationship between Urbanization, Economic Growth and Energy Consumption in China: An Econometric Perspective Analysis

by Yabo Zhao and Shaojian Wang

Sustainability 2015, 7(5), 5609-5627; https://doi.org/10.3390/su7055609 - 07 May 2015

Cited by 126 | Viewed by 12603

Abstract

As the largest developing country in the world, with rapid economic growth, China has witnessed fast-paced urbanization development over the past three decades. In fact, urbanization has been shown to promote economic growth and improve the livelihood of people, but it can also [...] Read more.

As the largest developing country in the world, with rapid economic growth, China has witnessed fast-paced urbanization development over the past three decades. In fact, urbanization has been shown to promote economic growth and improve the livelihood of people, but it can also increase energy consumption and further generate energy crisis. Therefore, a better understanding of the relationship between urbanization, economic growth and energy consumption is important for China’s future sustainable development. This paper empirically investigates the long-term equilibrium relationships, temporal dynamic relationships and causal relationships between urbanization, economic growth and energy consumption in China. Econometric models are utilized taking the period 1980–2012 into consideration. Cointegration tests indicate that the variables are found to be of I(1) and cointegrated. Further, vector error-correction model (VECM) indicates that when the short-term fluctuations deviate from the long-term equilibrium, the current changes of energy consumption could eliminate 9.74% non-equilibrium error of the last period, putting back the situation to the equilibrium state through a reverse adjustment. Impulse response analysis intuitively portrays the destabilized changes of the variables in response to some external shocks. However, the impact of energy consumption shock on urbanization and the impact of urbanization on economic growth seem to be rather marginal. Moreover, Granger causality results reveal that there is a bi-directional Granger causal relationship between energy consumption and economic growth, and unidirectional causality running from urbanization to energy consumption and economic growth to urbanization. The findings have important implications for Chinese policymakers that on the path towards a sustainable society, the effects of urbanization and economic growth on energy consumption must be taken into consideration. Full article

(This article belongs to the Special Issue Energy Conversion System Analysis)

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