This paper investigates the performance and economic viability of Combined Cycle Gas Turbines (CCGT) operating on natural gas (NG) and hydrogen within the context of evolving electricity markets. The study is structured into several sections, beginning with a benchmark analysis to establish baseline performance metrics, including break-even prices and price margins for CCGTs running on NG. The research then explores various base cases and sensitivity analyses, focusing on different CCGT capacity factors and the uncertainties surrounding key parameters. The study also compares the performance of CCGTs across different European countries, highlighting the impact of increased price fluctuations in forecasted electricity markets. Additionally, the paper examines Power-to-X-to-Power (P2X2P) configurations, assessing the economic feasibility of hydrogen production and its integration into CCGT operations. The analysis considers scenarios where hydrogen is sourced externally or produced on-site using renewable energy or grid electricity during off-peak hours. The results provide insights into the competitiveness and adaptability of CCGTs in a transitioning energy landscape, emphasizing the potential role of hydrogen as a flexible and sustainable energy carrier. 

Power-to-Ammonia (P2A) is a promising technology that can provide a low-emission energy carrier for long-term storage. This study presents an optimization approach to a novel small-scale containerized P2A concept commissioned in 2024. A dynamic nonlinear optimization problem of the P2A concept is set up, employing the non-commercial MOSAIC (R) software V3.0.1 in combination with the NEOS (R) server. In total, seven optimization solvers, ANTIGONE (R), CONOPT (R), IPOPT (R), KNITRO (R), MINOS (R), PATHNLP (R), and SNOPT (R), are used. The first and main part of this work optimizes several disturbance scenarios of the concept and aims to determine the optimal reactor temperature profile to counter the disturbances. The optimization results suggest, for example, lowering the reactor temperature profile if the hydrogen and nitrogen inlet streams into the system decrease. The second part of this work presents a crude dynamic optimal scheduling model. This part aims to determine the amount of ammonia to be produced and sold given a randomized price of electricity for three consecutive points in time. The optimization results recommend decreasing production when the price of electricity is high and vice versa. However, the dynamic model must be improved to include fluctuations in the price of ammonia. Then, it can be used as a real-time optimization tool.

The integration of a heat pump (HP) with a combined cycle gas turbine (CCGT) to control the inlet air temperature is a promising technology to meet the requirements imposed by the current electricity systems in terms of efficiency and flexibility. If the HP is coupled with a thermal energy storage (TES) in an inlet conditioning unit (ICU), it can be exploited in different modes to enhance the off-design CCGT's efficiency or to boost the power output at full load. Furthermore, fuel-saving would be reflected in avoided emissions. The optimal sizing of the ICU, as well as an accurate estimation of the benefits, is a complex problem influenced by several factors such as the local climate and electricity market prices. This paper aims to systematically investigate, utilizing a mixed integer linear programming (MILP) model for optimal dispatch, the feasibility of an ICU integration in different scenarios (EU and US). Different electricity markets have been analyzed and classified according to the parameters describing the average and variability of prices, the interdependency with the gas market, the ambient temperature, or the local carbon pricing policy. The most favorable conditions are identified and the dependency of the optimal ICU sizing on the climate and the electricity market is highlighted. This paper provides information for a first viability assessment: the concept appears to be highly profitable in hot regions with high price variability. Additionally, even in less profitable conditions (i.e., stable low prices in a cold climate), the system increases operating hours and reduces economic losses.

Herein, a novel methodology to perform optimal sizing of AC-linked solar PV-PEM systems is proposed. The novelty of this work is the proposition of the solar plant to electrolyzer capacity ratio (AC/AC ratio) as optimization variable. The impact of this AC/AC ratio on the Levelized Cost of Hydrogen (LCOH) and the deviation of the solar DC/AC ratio when optimized specifically for hydrogen production are quantified. Case studies covering a Global Horizontal Irradiation (GHI) range of 1400–2600 kWh/m2-year are assessed. The obtained LCOHs range between 5.9 and 11.3 USD/kgH2 depending on sizing and location. The AC/AC ratio is found to strongly affect cost, production and LCOH optimality while the optimal solar DC/AC ratio varies up to 54% when optimized to minimize the cost of hydrogen instead of the cost of energy only. Larger oversizing is required for low GHI locations; however, H2 production is more sensitive to sizing ratios for high GHI locations.

Natural gas turbine combined cycles (GTCCs) are playing a fundamental role in the current energy transition phase towards sustainable power generation. The competitiveness of a GTCC in future electrical networks will thus be firmly related to its capability of successfully compensating the discontinuous power demands. This can be made possible by enhancing power generation flexibility and extending the operative range of the plant. To achieve this goal, a test rig to investigate gas turbine inlet conditioning techniques was developed at the TPG laboratory of the University of Genoa, Italy. The plant is composed of three key hardware components: a micro gas turbine, a butane-based heat pump, and a phase-change material cold thermal energy storage system. The physical test-rig is virtually scaled up through a cyber-physical approach, to emulate a full scale integrated system. The day-ahead schedule of the plant is determined by a high-level controller referring to the Italian energy market, considering fluctuations in power demands. By using HP and TES, it is possible to control the mGT inlet air temperature and thus enhance the operational range of the plant optimizing the management of energy flows. This article (Part 1) introduces the new experimental facility, the real-time bottoming cycle dynamic model, and the four-level control system that regulates the operation of the whole cyber-physical plant. The experimental campaign and the analysis of the system performance are presented in the Part 2. 

Hydrogen as an energy vector is seen as a fundamental enabler to the energy transition toward a low-carbon energy future not only from the power perspective but also from a primary energy one. In fact, not only is it conceivable as an electricity storage method (Power-to-X-to-Power) that can contribute to the safe increase of penetration stochastic renewable electricity to the grid but it also represents a versatile cross-vector medium enabling the deep decarbonization of non-electrified hard-to-abate sectors (renewable fuels, sector integration, mobility, etc.). In this context, great political and economic interest has risen related to the deployment of hydrogen technologies in the past few years, leading most key players – both industries and institutions – to include hydrogen technologies in national industrial strategies and development programs. In this chapter – after a brief overview of the state of the art of the main hydrogen technologies (declined for each section of the value chain) – an application-driven analysis of what will be the foreseen role of hydrogen technologies in future integrated energy systems is provided, considering a wide range of applications such as energy storage, grid flexibility services, renewable feedstocks for heavy industries, and fuel cells for both stationary μ-CHP and automotive applications. Ultimately, a list of worldwide key breakthrough projects of the period 2000–2020 is provided to show the history and development of hydrogen technology toward market maturity.

Combined Cycle Gas Turbines, CCGTs, are oftenconsidered as the bridging technology to a decarbonized energysystem thanks to their high exploitation rate of the fuel energeticpotential. At present time in most European countries, however,revenues from the electricity market on their own are insufficientto operate existing CCGTs profitably, also discouraging newinvestments and compromising the future of the technology. Inaddition to their high efficiency, CCGTs offer ancillary servicesin support of the operation of the grid such as spinning reserveand frequency control, thus any potential risk of plantdecommissioning or reduced investments could translate into arisk for the well-functioning of the network. To ensure thereliability of the electricity system in a transition towards ahigher share of renewables, the economic sustainability ofCCGTs must be preserved, for which it becomes relevant tomonetize properly the ancillary services provided. In this paper,an accurate statistical analysis was performed on the day-ahead,intra-day, ancillary service, and balancing markets for the wholeItalian power-oriented CCGT fleet. The profitability of 45 realproduction units, spread among 6 market zones, was assessed onan hourly basis considering local temperature, specific plantlayouts, and off-design performance. The assessment revealedthat net income from the ancillary service market doubled, onaverage, the one from the day-ahead energy market. It wasobserved that to be competitive in the ancillary services marketCCGTs are required to be more flexible in terms of ramp rates,minimum environmental loads, and partial load efficiencies.This paper explores how integrating a Heat Pump and a ThermalEnergy Storage within a CCGT could allow improving itscompetitiveness in the ancillary services market, and thus itsprofitability, by means of implementing a model of optimaldispatch operating on the ancillary services market

Under new scenarios with high shares of renewable electricity, combined cycle gas turbines (CCGTs) are required to improve their flexibility to help balance the power system. Simultaneously, liberalization of electricity markets and the complexity of its hourly price dynamics are affecting the CCGT profitability, leading the need for optimizing its operation. An inlet conditioning unit (ICU) offers the benefit of power augmentation and “minimum environmental load” (MEL) reduction by controlling the gas turbine (GT) inlet temperature using cold thermal energy storage (TES) and a heat pump (HP). Consequently, an evaluation of a CCGT integrated with this unit including a day-ahead optimized operation strategy was developed in this study. To establish the hourly dispatch of the power plant and the operation mode of the ICU, a mixed-integer linear programing (MILP) optimization was formulated, aiming to maximize the operational profit of the plant within a 24 h horizon. To assess the impact of the unit operating under this dispatch strategy, historical data have been used to perform annual simulations of a reference power plant located in Turin, Italy. Results indicate that the power plant's operational profit increases by achieving a wider operational range during peak and off-peak periods. For the specific case study, it is estimated that the net present value (NPV) of the CCGT integrated with the ICU is 0.5% higher than the CCGT without it. Results also show that the unit reduces the MEL by approximately 1.34% and can increase the net power output by 0.17% annually.

Under new scenarios with high shares of variable renewable electricity, combined cycle gas turbines (CCGT) are required to improve their flexibility, in terms of ramping capabilities and part-load efficiency, to help balance the power system. Simultaneously, liberalization of electricity markets and the complexity of its hourly price dynamics are affecting the CCGT profitability, leading the need for optimizing its operation. Among the different possibilities to enhance the power plant performance, an inlet air conditioning unit (ICU) offers the benefit of power augmentation and “minimum environmental load” (MEL) reduction by controlling the gas turbine inlet temperature using cold thermal energy storage and a heat pump. Consequently, an evaluation of a CCGT integrated with this inlet conditioning unit including a day-ahead optimized operation strategy was developed in this study. 

The present study presents a techno-economic analysis of a novel power plant layout developed to increase the dispatch flexibility of a Combined Cycle Gas Turbine (CCGT) coupled to a District Heating Network (DHN). The layout includes the incorporation of high temperature heat pumps (HP) and thermal energy storage (TES). A model for optimizing the short-term dispatch strategy of such system has been developed to maximize its operational profit. The constraints and boundary conditions considered in the study include hourly demand and price of electricity and heat, ambient conditions and CO2 emission allowances. To assess the techno-economic benefit of the new layout, a year of operation was simulated for a power plant in Turin, Italy. Furthermore, different layout configurations and critical size-related parameters were considered. Finally, a sensitivity analysis was made to assess the performance under different market scenarios.

The results show that it is indeed beneficial, under the assumed market conditions, to integrate a HP in a CCGT plant coupled to a DHN, and that it remains profitable to do so under a variety of market scenarios. The best results for the assumed market conditions were found when integrating a 15 MWth capacity HP in the 400 MWel CCGT-CHP. For this case study, the investment in the HP would yield a net present value (NPV) of 1.22 M€ and an internal rate of return (IRR) of 3.04% for a lifetime of 20 years. An increase was shown also in operational flexibility with 0.14% of the electricity production shifted while meeting the same heating demand. Additionally, it was found that the TES makes the system even more flexible, but does not make up for the extra investment.