scholarly journals Geothermal power plants with improved environmental performance: assessment of the potential for an Italian site

2021 ◽  
Vol 238 ◽  
pp. 01010
Author(s):  
Daniele Fiaschi ◽  
Martina Leveni ◽  
Giampaolo Manfrida ◽  
Barbara Mendecka ◽  
Lorenzo Talluri

Geothermal energy is a clean resource, which could significantly contribute to the reduction of greenhouse and other gas emissions by replacing fossil fuels for power generation. In many geothermal sites, the resource contains substantial Non-Condensable Gases (NCGs: CO2 and contaminants), whose emissions can be limited to developing power plant schemes suitable for complete resource reinjection. Organic Rankine or other closed-loop cycles are definitely favored in this light. This work investigates a solution for complete NCG reinjection in the liquid-dominated reservoir conditions typical of the Monte Amiata area (Italy), referring to the specific site of Torre Alfina (IT) which presents a specific attractiveness because of its high pressurization. The solution considered avoids flashing the resource and thus presents an appealing environmental performance. The power plant models include energy and exergy balances, as well as exergo-environmental analysis. The overall environmental performance is evaluated by a simplified (preliminary) Life Cycle Analysis (LCA). Different solutions are compared, considering the possibility of sub- or super-critical power cycles.

Author(s):  
Obumneme Oken

Nigeria has some surface phenomena that indicate the presence of viable geothermal energy. None of these locations have been explored extensively to determine the feasibility of sustainable geothermal energy development for electricity generation or direct heating. In this context, the present study aims to provide insight into the energy potential of such development based on the enthalpy estimation of geothermal reservoirs. This particular project was conducted to determine the amount of energy that can be gotten from a geothermal reservoir for electricity generation and direct heating based on the estimated enthalpy of the geothermal fluid. The process route chosen for this project is the single-flash geothermal power plant because of the temperature (180℃) and unique property of the geothermal fluid (a mixture of hot water and steam that exists as a liquid under high pressure). The Ikogosi warm spring in Ekiti State, Nigeria was chosen as the site location for this power plant. To support food security efforts in Africa, this project proposes the cascading of a hot water stream from the flash tank to serve direct heat purposes in agriculture for food preservation, before re-injection to the reservoir. The flowrate of the geothermal fluid to the flash separator was chosen as 3125 tonnes/hr. The power output from a single well using a single flash geothermal plant was evaluated to be 11.3 MW*. This result was obtained by applying basic thermodynamic principles, including material balance, energy balance, and enthalpy calculations. This particular project is a prelude to a robust model that will accurately determine the power capacity of geothermal power plants based on the enthalpy of fluid and different plant designs.


Author(s):  
Reynir S. Atlason ◽  
Oli P. Geirsson ◽  
Ari Elisson ◽  
Runar Unnthorsson

Iceland relies greatly on geothermal energy, for electricity, district heating and industrial activities. It is therefore of great importance that the maintenance on site is carried out quite successfully to minimize down time. Reykjavik Energy is the largest energy company in Iceland utilizing geothermal energy. The company operates two cogenerating geothermal power plants, Hellisheidi (303 MWe and 133 MWt) and Nesjavellir (120 MWe and 300 MWt). In this study we investigate the development of the wellhead maintenance at the Hellisheidi geothermal power plant. We look at the maintenance recommendations provided to on-site employees and how maintenance procedures have developed since the power plant began its operations. We investigate real data retrospectively and use it to calculate expected waiting times between repairs. The result is a maintenance model based on the observed and statistically analyzed data provided by the power company on the maintenance procedures. Such model should prove of great significance to other geothermal power plants in the early stages of planning the wellhead maintenance.


Author(s):  
Henry Egware ◽  
Albert I. Obanor ◽  
Harrison Itoje

Energy and exergy analyses were carried out on an active 42MW open cycle gas turbine power plant. Data from the power plant record book were employed in the investigation. The First and Second Laws of Thermodynamics were applied to each component of the gas power plant at ambient air temperature range of 21 - 330C. Results obtained from the analyses show that the energy and exergy efficiencies decrease with increase in ambient air temperature entering the compressor. It was also shown that 66.98% of fuel input and 54.53% of chemical exergy are both lost to the environment as heat from the combustion chamber in the energy and exergy analysis respectively. The energy analysis quantified the efficiency of the plant arising from energy losses , while exergy analysis revealed the magnitude of losses in various components of the plant. Therefore a complete thermodynamic evaluation of gas turbine power plants requires the use of both analytical methods.


Author(s):  
Nela Slavu ◽  
Cristian Dinca

Abstract One of the way to reduce the greenhouses gases emissions generated by the fossil fuels combustion consists in the Carbon Capture, Transport and Storage (CCS) technologies utilization. The integration of CCS technologies in the coal fired power plants increases the cost of the energy generation. The CCS technology could be a feasible solution in the case of a high value of a CO2 certificate but for the present value an optimization of the CCS technology integration in the power plants is expected. However, for reducing the cost of the energy generated in the case of CCS integration in the power plants, a parametrical study optimization of the CO2 capture process is required. In this study, the chemical absorption process was used and the monoethanolamine with 30 wt. %. The objective of this paper is to analyze the effects of the package type used in the absorption column on the size of the equipment used and, on the energy cost of the power plant with CO2 capture process consequently. The packages types analyzed in this paper are metal Pall rings with different sizes and the rings are made of different metals: aluminum, nickel, cooper, and brass. In the case of metal Pall rings, the utilization of different material has an impact on the absorption column weight. Also, Pall rings made of plastics (polypropylene and polyethylene) were analyzed. The comparative assessment was achieved for a coal fired power plant with an installed power of 100 MW and considering the CO2 capture process efficiency of 90 %.


Resources ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 84
Author(s):  
Margarida Casau ◽  
Diana C. M. Cancela ◽  
João C. O. Matias ◽  
Marta Ferreira Dias ◽  
Leonel J. R. Nunes

Energy consumption is associated with economic growth, but it comes with a toll regarding the environment. Renewable energies can be considered substitutes for fossil fuels and may contribute to reducing the environmental degradation that the world is presently facing. With this research, we aimed to offer a broader view of the state-of-the-art in this field, particularly regarding coal and biomass. The main objective is to present a viable and sustainable solution for the coal power plants still in operation, using as a hypothetical example the Pego Power Plant, the last operating coal fueled power plant in Portugal. After the characterization of land use and energy production in Portugal, and more particularly in the Médio Tejo region, where the power plant is located, the availability of biomass was assessed and it was concluded that the volume of biomass needed to keep the Pego power plant working exclusively with biomass is much lower than the yearly growth volume of biomass in the region, which means that this transition would be viable in a sustainable way. This path is aligned with policies to fight climate change, since the use of biomass for energy is characterized by low levels of GHGs emissions when compared to coal. The risk of rural fires would be reduced, and the economic and social impact for this region would be positive.


Author(s):  
Soumya Jyoti Chatterjee ◽  
Goutam Khankari ◽  
Sujit Karmakar

The comparative performance study is carried out for 500 MW Supercritical (SupC) Oxy-Coal Combustion (OCC) and Air-Coal Combustion (ACC) power plants with membrane-based CO2 capture at the fixed furnace temperature. The proposed configurations are modelled using a computer-based analysis software 'Cycle-Tempo' at different operating conditions, and the detailed thermodynamic study is done by considering Energy, Exergy, and Environmental (3-E) analysis. The result shows that the net energy and exergy efficiencies of ACC power plants with CO2 capture are about 35.07 % and 30.88 %, respectively, which are about 6.44 % and 5.77 % points, respectively higher than that of OCC power plant. Auxiliary power consumption of OCC based power plant is almost 1.97 times more than that of the ACC based plant due to huge energy utilization in the Air Separation Unit (ASU) of OCC plant which leads to performance reduction in OCC plant. However, environmental benefit of OCC based power plant is more than that of ACC based power plant with respect to CO2 emission. OCC plant emits about 0.164 kg/kWh of CO2 which is approximately 16.75 times lower than the CO2 emission in ACC based power plant. It is also analyzed that the performance of the CO2 Capture Unit (CCU) for the OCC based plant is about 3.65 times higher than the ACC based power plant due to higher concentration of CO2 (nearly 80.63%) in the flue gas emitting from OCC plant. The study also reveals that the auxiliary power consumption per kg of CO2 capture of the OCC based plant is about 0.142 kWh/kg, which is approximately 0.06 times lower than the ACC based plant. The higher performance of the OCC based power plant is found at lower value of flue gas recirculation due to the fact that reduction in exergy destruction at the mixing zone of the combustor is higher than the increase in exergy destruction of the heat exchangers at higher furnace exit temperature. But the metallurgical temperature limit of boiler tube materials restricts the use of the higher value of furnace temperature. OCC based power plant with CO2 capture can be preferred over ACC based plant with CO2 capture due to higher environmental benefits towards mitigating CO2, the key greenhouse gas on earth in spite of exhibiting lesser energy and exergy efficiencies.


2018 ◽  
Vol 204 ◽  
pp. 04013 ◽  
Author(s):  
Rima Septiani Prastika ◽  
A.N. Afandi ◽  
Dwi Prihanto

Recently, electric usages are increasing every year by year in many sectors. In facts, fossil fuels have been fueled to produce electrical energy availability at many power plants which are very limited for the sustainable procurement. Developing and implementing renewable energy sources should be urgently promoted to reduce the dependence on fossil fuels that have been fueled to generate electricity for the long period throughout various power plant combinations. In expectation, the natural source of electrical energy which environmentally friendly and easy to obtain in nature is recommended to explore for the existing energy producers. The natural source of energy can be operated as an alternative power plant to reduce environmental effects and to decrease air contaminants. These works cover those opportunities. In these studies, the method used is a quantitative category with collected primary and secondary data for all evaluations and mitigations. In general, these works are also designed for identifying problems and looking for literature, data collection, processing stage, analysis phase, and final conclusion. The data used is defined in terms of temperature, air pressure, and wind speed. The collected data are supposed to the Purwoharjo City of Banyuwangi Regency, with 10 meters above ground level. Naturally, the wind speed is about 3.5 m/s to 4 m/s and the average temperature is 300° Kelvin. The potentially generated wind energy at a single point of coordinates is around 85.17 Wh.


2011 ◽  
Vol 110-116 ◽  
pp. 4772-4779
Author(s):  
Kumar Ashlesh ◽  
Rohit Vadera ◽  
K. Ramachandra

The use of woody biomass gasification based power plants to generate electricity is on the rise with the fast depletion of fossil fuels and ever increasing energy demands. An important sub-system of such a plant is the drier which is used to reduce the moisture content of biomass to an optimum level for trouble free and optimum performance of the gasification system. This work concerns with the design, development and implementation of a drier system which utilizes waste heat available from the power plant to dry biomass. The drier designed is simple yet effective in capturing the waste heat from the engine exhaust as well as the radiator hot air. The drier is also easy to implement in rural areas.


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