Identifying opportunities for developing CSP and PV-CSP hybrid projects under current tender conditions and market perspectives in MENA – benchmarking with PV-CCGT

Concentrating solar power (CSP) is one of the promising renewable energy technologies provided the fact that it is equipped with a cost-efficient storage system, thermal energy storage (TES). This solves the issue of intermittency of other renewable energy technologies and gives the advantage of achieving higher capacity factors and lower levelized costs of electricity (LCOE). This is the main reason why solar tower power plants (STPP) with molten salts and integrated TES are considered one of the most promising CSP technologies in the short term [1]. On the other hand, solar photovoltaic (PV) is a technology whose costs have been decreasing and are expected to continue doing so thus providing competitive LCOE values, but with relatively low capacity factors as electrical storage systems remain not cost-effective. Combining advantages and eliminating drawbacks of both technologies (CSP and PV), Hybridized PV-CSP power plants can be deemed as a competitive economic solution to offer firm output power when CSP is operated smartly so that its load is regulated in response to the PV output. Indeed previous works, have identified that it would allow achieving lower LCOEs than stand-alone CSP plants by means of allowing it to better utilize the solar field for storing energy during the daytime while PV is used [1]. On the fossil-based generation side, the gas turbine combined cycle (CCGT) occupies an outstanding position among power generation technologies. This is due to the fact that it is considered the most efficient fossil fuel-to-electricity converter, in addition to the maturity of such technology, high flexibility, and the generally low LCOE, which is largely dominated by fuel cost and varies depending on the natural gas price at a specific location. Obviously, the main drawback is the generated carbon emissions. In countries rich in natural gas resources and with vast potential for renewable energies implementation, such as the United Arab Emirates (UAE), abandoning a low LCOE technology with competitively low emissions – compared to coal or oil - and heading to costly pure renewable generation, seems like an aggressive plan. Therefore, hybridizing CCGT with renewable generation can be considered an attractive option for reducing emissions at reasonable costs. This is the case of the UAE with vast resources of both natural gas and solar energy. Previous work have shown the advantages of hybrid PV-CCGT and hybrid PV-CSP plants separately [1][2]. In this thesis, CSP and the two hybrid systems are compared on the basis of LCOE and CO2 emissions for a same firm-power capacity factor when considering a location in the UAE. The results are compared against each other to highlight the benefits of each technology from both environmental and economic standpoints and provide recommendations for future work in the field. The techno-economic analysis of CSP (STPP with TES), PV-CSP(STPP with TES) and PV-CCGT power plants have been performed by DYESOPT, an in-house tool developed in KTH, which runs techno-economic performance evaluation of power plants through multi-objective optimization for specific locations[1]. For this thesis, a convenient location in the UAE was chosen for simulating the performance of the plants. The UAE is endowed by the seventh-largest proven natural gas reserves and average to high global horizontal irradiation (GHI) and direct normal irradiation (DNI) values all year round, values considered to be lower than other countries in the MENA region due to its high aerosol concentrations and sand storms. The plants were designed to provide firm power in two cases, first as baseload, and second as intermediate load of 15 hours from 6:00 until 21:00. The hours of production were selected based on a typical average daily load profile. CSP and PV-CSP model previously developed by [3][1] were used. Ideally in the PV-CSP model, during daytime hours the PV generation is used for electricity production, covering the desired load, while CSP is used partly for electricity production and the rest for storing energy in the TES. Energy in the TES system is then used to supply firm power during both periods of low Irradiance and night hours or according to need. A PV-CCGT model has been developed which operates simultaneously, prioritizing the availability of PV while the CCGT fulfils the remaining requirement. There is a minimum loading for the CCGT plant which is determined by the minimum possible partial loading of the gas turbine restricted by the emission constraints. Accordingly, in some cases during operation PV is chosen to be curtailed due to this limitation. The main results of the techno-economic analysis are concluded in the comparative analysis of the 3 proposed power plant configurations, where the PV-CCGT plant is the most economic with minimum LCOE of 86 USD/MWh, yet, the least preferable option in terms of carbon emissions. CSP and PV-CSP provided higher LCOE, while the PV-CSP plant configuration met the same capacity factor with 11% reduction in LCOE, compared to CSP

Computational technique for compressible vortex flows using the integral equation solution

The steady full-potential equation is written in the form of Poisson's equation, and the solution for the velocity field is expressed in terms of an integral equation. The integral solution consists of two surface integrals and one volume integral. The solution is obtained through successive iteration cycles. Each cycle of iteration consists of two sub-cycles, an inner cycle for wake relaxation and an out cycle for the strength of the source distribution integrals representing the flow compressibility. The density gradients in the source distribution is computed by using a type-differencing scheme of the Murman-Cole type. The method is applied to delta wings and the numerical examples show that a curved shock is captured on the wing suction side beneath the leading edge vortex sheet. Recently, a modified version of the scheme was applied to rectangular wings. In this modified scheme, the surface integral terms were computed by using a bilinear distribution of vorticity on triangular vortex panels which represent the wing and its wake. The results were compared with the available experimental data and they are in good agreement

Unsteady hybrid vortex technique for transonic vortex flows and flutter application

Papers resulting from work performed from January 1, 1987 to July 31, 1987 are listed. Transonic computational schemes based on Integral Equation Formulation of the full potential equation were presented. Classical and zero-total pressure-loss sets of Euler equations applied to delta wings were examined

Fostering south-south research collaborations

This repository item contains a single issue of Issues in Brief, a series of policy briefs that began publishing in 2008 by the Boston University Frederick S. Pardee Center for the Study of the Longer-Range Future.This policy brief reviews the state of research collaborations between and amongst developing country scholars – South-South research collaborations and develops a rationale for a more systematic and multilateral approach to such endeavors

Analysis and mitigation of numerical dissipation in inviscid and viscid computation of vortex-dominated flows

The conservative unsteady Euler equations for the flow relative motion in the moving frame of reference are used to solve for the steady and unsteady flows around sharp-edged delta wings. The resulting equations are solved by using an implicit approximately-factored finite volume scheme. Implicit second-order and explicit second- and fourth-order dissipations are added to the scheme. The boundary conditions are explicitly satisfied. The grid is generated by locally using a modified Joukowski transformation in cross flow planes at the grid chord stations. The computational applications cover a steady flow around a delta wing whose results serve as the initial conditions for the unsteady flow around a pitching delta wing about a large angle of attack. The steady results are compared with the experimental data and the periodic solution is achieved within the third cycle of oscillation