scholarly journals A Thermodynamic Analysis of Tubular SOFC Based Hybrid Systems

2001 ◽  
Author(s):  
A. D. Rao ◽  
G. S. Samuelsen
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Hybrid Systems ◽  
Carbon Tax ◽  
Hybrid Plant ◽  
Cost Of Electricity ◽  
Efficiency Performance ◽  
Analysis Strategy ◽  
The University ◽  
Gas Price

The goals of a research program recently completed at the University of California, Irvine were to develop analysis strategy for Solid Oxide Fuel Cell (SOFC) based systems, to apply the analysis strategy to tubular SOFC hybrid systems and to identify promising hybrid configurations. A pressurized tubular SOFC combined with an intercooled-reheat gas turbine (SureCell™ cycle) is chosen as the Base Cycle over which improvements are sought. The humid air turbine (HAT) cycle features are incorporated to the Base Cycle resulting in the SOFC-HAT hybrid cycle which shows an efficiency of 69.05% while the Base Cycle has an efficiency of 66.23%. Exergy analysis identified the superior efficiency performance of the SOFC component. Therefore, an additional cycle variation added a second SOFC component followed by a low pressure combustor in place of the reheat combustor of the gas turbine of the SOFC-HAT hybrid. The resulting Dual SOFC-HAT hybrid has a thermal efficiency of 75.98%. The Single SOFC-HAT hybrid gives the lowest cost of electricity (3.54¢/kW-hr) while the Dual SOFC-HAT hybrid has the highest cost of electricity (4.02¢/kW-hr) among the three cycles with natural gas priced at $3/GJ. The Dual SOFC-HAT hybrid plant cost is calculated to be significantly higher because the fraction of power produced by the SOFC(s) is significantly higher than that in the other cases on the basis of $1100/kw initial cost for the SOFC. The Dual SOFC-HAT hybrid can only be justified in favor of the Single SOFC-HAT hybrid when price of natural gas is greater than $14/GJ or if a severe carbon tax on the order of $180/ton of CO2 is imposed while natural gas price remains at $3/GJ.

scholarly journals A Thermodynamic Analysis of Tubular Solid Oxide Fuel Cell Based Hybrid Systems

2002 ◽  
Vol 125 (1) ◽  
pp. 59-66 ◽  
Author(s):  
A. D. Rao ◽  
G. S. Samuelsen
Keyword(s):  
Fuel Cell ◽  
Natural Gas ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Hybrid Systems ◽  
Hybrid Plant ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Cost Of Electricity ◽  
Analysis Strategy

The goals of a research program recently completed at the University of California, Irvine were to develop analysis strategy for solid oxide fuel cell (SOFC) based systems, to apply the analysis strategy to tubular SOFC hybrid systems and to identify promising hybrid configurations. A pressurized tubular SOFC combined with an intercooled-reheat gas turbine (SureCell™ cycle) is chosen as the base cycle over which improvements are sought. The humid air turbine (HAT) cycle features are incorporated to the base cycle resulting in the SOFC-HAT hybrid cycle which shows an efficiency of 69.05 percent while the base cycle has an efficiency of 66.23 percent. Exergy analysis identified the superior efficiency performance of the SOFC component. Therefore, an additional cycle variation added a second SOFC component followed by a low pressure combustor in place of the reheat combustor of the gas turbine of the SOFC-HAT hybrid. The resulting dual SOFC-HAT hybrid has a thermal efficiency of 75.98 percent. The single SOFC-HAT hybrid gives the lowest cost of electricity (3.54¢/kW-hr) while the dual SOFC-HAT hybrid has the highest cost of electricity (4.02¢/kW-hr) among the three cycles with natural gas priced at $3/GJ. The dual SOFC-HAT hybrid plant cost is calculated to be significantly higher because the fraction of power produced by the SOFC(s) is significantly higher than that in the other cases on the basis of $1100/kw initial cost for the SOFC. The dual SOFC-HAT hybrid can only be justified in favor of the single SOFC-HAT hybrid when the price of natural gas is greater than $14/GJ or if a severe carbon tax on the order of $180/ton of CO2 is imposed while natural gas price remains at $3/GJ.

scholarly journals Energetic and Economic Analyses of an LCPV/T Solar Hybrid Plant for a Sports Center Building in Mexico

Energies ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 5681
Author(s):  
Iván Acosta-Pazmiño ◽  
Carlos Rivera-Solorio ◽  
Miguel Gijón-Rivera
Keyword(s):  
Natural Gas ◽  
Winter Season ◽  
Hybrid Plant ◽  
Hot Water ◽  
Electrical Performance ◽  
Payback Time ◽  
Economic Analyses ◽  
Levelized Cost Of Heat ◽  
Solar Field ◽  
Gas Price

This study presents a techno-economic performance evaluation of a hybrid low-concentrating photovoltaic/thermal (LCPV/T) plant, which operates in a student sports and wellness center building situated at a university campus in Mexico. The solar plant comprises 144 LCPV/T collectors based on a hybridized version of a local parabolic trough technology. Dynamic thermal and electrical performance analyses were performed in the TRNSYS simulation studio. The results showed that the solar field could cover up to 72% of the hot water demand of the building during the summer season and 24% during the winter season. The hybrid system could annually save 7185 USD, accounting for heat (natural gas boiler) and electricity generation. However, the payback time was of 19.23 years, which was mainly attributed to a reduced natural gas price in Monterrey, Mexico. A new approach to evaluating the equivalent levelized cost of heat (LCOHeq), is proposed. This results in an LCOHeq of 0.065 USD/kWh, which is nearly equivalent to the LCOH of a natural gas-fired boiler (0.067 USD/kWh). Finally, the hybrid plant could achieve a specific CO2e emission reduction of 77.87 kg CO2e per square meter of the required installation area.

scholarly journals Carbon Tax on Three Fossil Fuels

2019 ◽  
Vol 4 (2) ◽  
pp. 130-142
Author(s):  
James Stodder
Keyword(s):  
Natural Gas ◽  
Carbon Footprint ◽  
Fossil Fuels ◽  
Fossil Fuel ◽  
Carbon Tax ◽  
Tax Burden ◽  
Vector Auto Regression ◽  
Price Instability ◽  
Gas Price ◽  
Auto Regression

Carbon pricing will make Natural Gas the last fossil fuel. As is well-known, the carbon footprint of Oil is half-again as large, and the footprint of Coal is twice as large as that of Gas. Price sensitivities also imply that Gas producers bear relatively little of the total tax burden. As a result of the smaller tax on Gas, structured vector auto-regression (SVAR) simulations of a carbon tax show demand for Oil falling, with a rush for natural Gas. These simulations show that a modest ($40 per metric ton) carbon tax can be introduced gradually, avoiding price instability and achieving greater substitution into Gas than a tax ‘shock.’

Optimum Size of ORC Cycles for Waste Heat Recovery in Natural Gas Compressor Stations

2019 ◽  
Author(s):  
L. Branchini ◽  
M. A. Ancona ◽  
M. Bianchi ◽  
A. De Pascale ◽  
F. Melino ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Case Studies ◽  
Waste Heat ◽  
Carbon Tax ◽  
Economic Feasibility ◽  
Environmental Benefits ◽  
Optimum Size ◽  
Part Load ◽  
Design Power

Abstract The paper investigates the optimum size and potential economic, energetic and environmental benefits of ORC applications, as bottomer section in natural gas compressor stations. Since typical installations consist of multiple gas turbine units in mechanical drive arrangement, operated most of the time under part-load conditions, the economic feasibility of the ORC can become questionable even though the energetic advantage is indisputable. Depending on mechanical drivers profile during the year the optium size of the bottomer section must be carefully selected in order not to overestimate its design power output. To achieve this goal a numerical optimization procedure has been implemented in the Matlab environment, based on the integration of a in house-developed calculation code with a commercial software for the thermodynamic design and off-design analysis of complex energy systems (Thermoflex). Thus the optimal ORC design power size is identified in the most generic scenario, in terms of compressors load profile, installation site conditions (i.e. ambient conditions and carbon tax value) and gas turbine models used as drivers. Two different objective functions are defined aiming at maximize the CO2 savings or the net present value. Different case studies are shown and discussed to prove the potential of the developed code. The comparison among the case studies highlights, chiefly, the influence of yearly mechanical drivers profile, part-load control strategy applied and carbon tax value on the ORC techno-economic feasibility.

Designing Solid Oxide Fuel Cell Gas Turbine Hybrid Systems Using Exergy Analysis

2006 ◽  
Author(s):  
K. J. Bosch ◽  
N. Woudstra ◽  
K. V. van der Nat
Keyword(s):  
Fuel Cell ◽  
Natural Gas ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Hybrid Systems ◽  
Exergy Analysis ◽  
Operating Conditions ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Exergy Losses

In conventional gas turbine systems combustion results in high exergy losses (∼30%) of fuel exergy input. Replacing the combustor with a high temperature fuel cell, like the Solid Oxide Fuel Cell (SOFC), will significantly reduce these exergy losses. As the SOFC electrochemically converts the natural gas, exergy losses are far lower (∼10%) compared to combustion. Natural gas entering a SOFC system has to be reformed first to hydrogen and carbon monoxide by steam reforming. Here it is chosen to use the heat generated by the fuel cell to drive the endothermic reforming reactions: internal reforming. The SOFC-GT system has the advantage that both fuel cell and gas turbine technology contribute to power production. In earlier work [1] several fuel cell system configurations with PEMFC, MCFC or SOFC, were analyzed studying the exergy flows. Here is focused on the SOFC-GT configuration, to get a detailed understanding of the exergy flows and losses through all individual components. Several configurations, combining the SOFC with the GT are possible. The selected operating conditions should prevent carbon deposition. Systems studies are performed to get more insight in the exergy losses in these combined systems. Exergy analysis facilitates the search for the high efficient SOFC-GT hybrid systems. Using exergy analysis, several useful configurations are found. Exergy losses are minimized by varying pressure ratio and turbine inlet temperature. Sensitivity studies, of equivalent cell resistance and fuel cell temperature, show that total system exergy efficiencies of more than 80% are conceivable, without using a bottoming cycle.

Fixed-Bed Coal Gasifiers Integrated With MCFC-GT Hybrid Systems for Distributed Power and Heat Generation

2008 ◽  
Author(s):  
Daniele Cocco ◽  
Fabio Serra ◽  
Vittorio Tola
Keyword(s):  
Natural Gas ◽  
Performance Assessment ◽  
Gas Turbine ◽  
Hybrid Systems ◽  
Heat Generation ◽  
Fixed Bed ◽  
Research Centre ◽  
Medium Size ◽  
Molten Carbonate ◽  
Distributed Power

In this paper, a performance assessment of coal gasification processes integrated with molten carbonate fuel cells (IG-MCFC) is reported on. The main aim of the study was to evaluate the performance of small and medium size IG-MCFC systems based on fixed-bed gasifiers for distributed power and heat generation. In particular, the plant configuration considered here was developed on the basis of the 700 kg/h fixed-bed up-draft coal gasifier located in the Sotacarbo Research Centre in Carbonia, Italy. The MCFC section is based on the DFC/T® hybrid system developed by FCE Inc., and includes a MCFC stack integrated with an indirectly heated gas turbine. Two different coals, namely a low and a high sulphur coal, were considered. Moreover, the performance of MCFC hybrid systems fuelled by natural gas and coal gas were also compared. The results of the performance assessment show that the optimum value of the gas turbine pressure ratio is around 3, which is very similar to that used by the DFC/T systems proposed by FCE Inc. and fuelled by natural gas. However, replacing methane with coal gases leads to a significant decrease in MCFC efficiency, on the order of 10–11 percentage points. On the whole, the performance assessment carried out in this paper demonstrates that IG-MCFC systems could be an interesting option for small- and medium-size power generation plants fuelled by coal as they can reach efficiencies of nearly 40%.

Optimizing Natural Gas Combined Cycle Part Load Operation

2019 ◽  
Author(s):  
Robert Flores ◽  
Jack Brouwer
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Combined Cycle ◽  
University Of California ◽  
Inlet Guide Vane ◽  
Outlet Temperature ◽  
Part Load ◽  
Carbon Neutrality ◽  
Natural Gas Combined Cycle ◽  
The University

Abstract The University of California, Irvine (UCI) uses a 19 MW natural gas combined cycle (NGCC) to provide nearly all campus energy requirements. Meanwhile, the University of California system has committed to achieving carbon neutrality at all facilities by 2025. This has resulted in an influx of new energy efficiency and onsite solar generation, increasing the duration of NGCC part load operation. In addition, the shift towards carbon neutrality has resulted in the pursuit of renewable natural gas via anaerobic digestion to replace conventional fossil fuels. The combination of other sources of renewable generation and the shift towards more expensive fuels has created the need to boost NGCC part load performance. This work focuses on the methods used at UCI to explore the NGCC operating space in order to optimize part-load performance. In this work, a physical gas turbine and heat recovery steam generator model are developed and used with an exhaustive search optimization method to predict maximum part load plant efficiency. NGCC control elements considered in this work include gas turbine inlet guide vane modulation and changing combustor outlet temperature. This optimization was also used to explore replacing the current engine with a two-shaft or smaller gas turbine. Results indicate that there are some possible benefits with increased modulation of inlet guide vanes, but the largest efficiency gains are achieved when allowing the compressor to operate at variable speed. Shifting towards a smaller engine could also enable more consistent full power operation, but must be paired with additional resources in order to meet the campus demand.

scholarly journals Comparison between Concentrated Solar Power and Gas-Based Generation in Terms of Economic and Flexibility-Related Aspects in Chile

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1063
Author(s):  
Catalina Hernández Moris ◽  
Maria Teresa Cerda Guevara ◽  
Alois Salmon ◽  
Alvaro Lorca
Keyword(s):  
Natural Gas ◽  
Solar Power ◽  
Renewable Energy Sources ◽  
Cost Effective ◽  
Hybrid Plant ◽  
Point Of View ◽  
Concentrated Solar Power ◽  
Economic Point ◽  
Hybrid Plants ◽  
Cost Of Energy

The energy sector in Chile demands a significant increase in renewable energy sources in the near future, and concentrated solar power (CSP) technologies are becoming increasingly competitive as compared to natural gas plants. Motivated by this, this paper presents a comparison between solar technologies such as hybrid plants and natural gas-based thermal technologies, as both technologies share several characteristics that are comparable and beneficial for the power grid. This comparison is made from an economic point of view using the Levelized Cost of Energy (LCOE) metric and in terms of the systemic benefits related to flexibility, which is very much required due to the current decarbonization scenario of Chile’s energy matrix. The results show that the LCOE of the four hybrid plant models studied is lower than the LCOE of the gas plant. A solar hybrid plant configuration composed of a photovoltaic and solar tower plant (STP) with 13 h of storage and without generation restrictions has an LCOE 53 USD/MWh, while the natural gas technology evaluated with an 85% plant factor and a variable fuel cost of 2.0 USD/MMBtu has an LCOE of 86 USD/MWh. Thus, solar hybrid plants under a particular set of conditions are shown to be more cost-effective than their closest competitor for the Chilean grid while still providing significant dispatchability and flexibility.

scholarly journals Gas Turbine Powered Campus Update

2019 ◽  
Vol 141 (05) ◽  
pp. 46-48
Author(s):  
Lee S. Langston
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combined Heat And Power ◽  
Educational Benefits ◽  
Heating And Cooling ◽  
The University

An updated report is given on the University of Connecticut’s gas turbine combined heat and power plant, now in operation for 13 years after its start in 2006. It has supplied the Storrs Campus with all of its electricity, heating and cooling needs, using three gas turbines that are the heart of the CHP plant. In addition to saving more than $180 million over its projected 40 year life, the CHP plant provides educational benefits for the University.

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