Applications & Pathways

The aeroderivative gas turbine is widely used as it demonstrates many advantages. Adding hydrogen to natural gas fuels can improve the performance of combustion. Following this the effects of hydrogen enrichment on combustion characteristics were analyzed in an aeroderivative gas turbine combustor using CFD simulations. The numerical model was validated with experimental results. The conditions of the constant mass flow rate and the constant energy input were studied. The results indicate that adding hydrogen reduced the fuel residues significantly (fuel mass at the combustion chamber outlet was reduced up to 60.9%). In addition the discharge of C2H2 and other pollutants was reduced. Increasing the volume fraction of hydrogen in the fuel also reduced CO emissions at the constant energy input while increasing CO emissions at the constant fuel mass flow rate. An excess in the volume fraction of added hydrogen changed the combustion mode in the combustion chamber resulting in fuel-rich combustion (at constant mass flow rate) and diffusion combustion (at constant input power). Hydrogen addition increased the pattern factor and NOx emissions at the outlet of the combustion chamber.

This paper presents a method for refining the forecast schedule of renewable energy sources (RES) generation by its intraday adjustment and investigates the measures for reserving RES with unstable generation in electric power systems (EPSs). Owing to the dependence of electricity generation by solar and wind power plants (PV and WPPs respectively) on natural conditions problems arise with their contribution to the process of balancing the power system. Therefore the EPS is obliged to keep a power reserve to compensate for deviations in RES from the planned generation amount. A system-wide reserve (mainly the shunting capacity of thermal and hydroelectric power plants) is used first followed by other means of power reserve: electrochemical hydrogen or biogas plants. To analyze the technical and economic efficiency of certain backup means mathematical models based on the theory of similarity and the criterion method were developed. This method is preferred because it provides the ability to compare different methods of backing up RES generation with each other assess their proportionality and determine the sensitivity of costs to the capacity of backup methods with minimal available initial information. Criterion models have been formed that allow us to build dependencies of the costs of backup means for unstable RES generation on the capacity of the backup means. It is shown that according to the results of the analysis of various methods and means of RES backup hydrogen technologies are relatively the most effective. The results of the analysis in relative units can be clarified if the current and near-term price indicators are known.

The optimal sizing of stand-alone renewable H2-based microgrids requires the load demand to be reliably satisfied by means of local renewable energy supported by a hybrid battery/hydrogen storage unit while minimizing the system costs. However this task is challenging because of the high number of components that have to be installed and operated. In this work an MILP optimization framework has been developed and applied to the off-grid village of Ginostra (on the Stromboli island Italy) which is a good example of several other insular sites throughout the Mediterranean area. A year-long time horizon was considered to model the seasonal storage which is necessary for off-grid areas that wish to achieve energy independence by relying on local renewable sources. The degradation costs of batteries and H2-based devices were included in the objective function of the optimization problem i.e. the annual cost of the system. Efficiency and investment cost curves were considered for the electrolyzer and fuel cell components in order to obtain a more detailed and precise techno-economic estimation. The design optimization was also performed with the inclusion of a general demand response program (DRP) to assess its impact on the sizing results. Moreover the effectiveness of the proposed MILP-based method was tested by comparing it with a more traditional approach based on a metaheuristic algorithm for the optimal sizing complemented with ruled-based strategies for the system operation. Thanks to its longer-term storage capability hydrogen is required for the optimal system configuration in order to reach energy self-sufficiency. Finally considering the possibility of load deferral the electricity generation cost can be reduced to an extent that depends on the amount of load that is allowed to participate in the DRP scheme. This cost reduction is mainly due to the decreased capacity of the battery storage system.

Automotive proton-exchange membrane fuel cells (PEMFCs) have finally reached a state of technological readiness where several major automotive companies are commercially leasing and selling fuel cell electric vehicles including Toyota Honda and Hyundai. These now claim vehicle speed and acceleration refueling time driving range and durability that rival conventional internal combustion engines and in most cases outperform battery electric vehicles. The residual challenges and areas of improvement which remain for PEMFCs are performance at high current density durability and cost. These are expected to be resolved over the coming decade while hydrogen infrastructure needs to become widely available. Here we briefly discuss the status of automotive PEMFCs misconceptions about the barriers that platinum usage creates and the remaining hurdles for the technology to become broadly accepted and implemented.

Considering the current environmental restrictions particularly those imposed on fossil fuel exploitation hydrogen stands out as a very promising alternative for the power and transportation sectors. This paper investigates the effects of the employment of hydrogen in a K9K automotive diesel engine. Experiments were conducted at a speed of 2000 min−1 with various engine load levels of 40% 55% 70% and 85%; several quantities were monitored to evaluate the performance with hydrogen use in terms of brake-specific energetic consumption (BSEC) fuel economy maximum pressure and heat-release characteristics. It was found that at 55% engine load the engine efficiency increased by 5.3% with hydrogen addition achieving a diesel fuel economy of 1.32 kg/h. The rate of increase of the peak pressure and maximum pressure started to increase as a consequence of the higher fuel quantity that burned in the premixed combustion phase while still remaining within reliable operational limits. The accelerated combustion and augmented heat release rate resulted in a combustion duration that was reduced by 3◦ CA (crank angle degree) achieving a mass fraction burned percentage of 10% to 90% earlier in the cycle and the combustion variability was also influenced. Hydrogen use assured the decrease of CO2 HC NOx and smoke emission levels in comparison with classic fueling.

Concerns about climate change air pollution and the depletion of oil resources have prompted authorities to enforce increasingly strict rules in the automotive sector. There are several benefits to implementing fuel cell hybrid vehicles (FCHV) in the transportation sector including the ability to assist in reducing greenhouse gas emissions by replacing fossil fuels with hydrogen as energy carriers. This paper examines different control strategies for optimizing the power split between the battery and PEM fuel cell in order to maximize the PEM fuel cell system efficiency and reduce fuel consumption. First the vehicle and fuel cell system models are described. A forward approach is considered to model the vehicle dynamics while a semi-empirical and quasi-static model is used for the PEM fuel cell. Then different rule-based control strategies are analyzed with the aim of maximizing fuel cell system efficiency while ensuring a constant battery state of charge (SOC). The different methods are evaluated while the FCHV is performing both low-load and high-load drive cycles. The hydrogen consumption and the overall fuel cell system efficiency are considered for all testing conditions. The results highlight that in both low-load cycles and high-load cycles the best control strategies achieve a fuel cell system efficiency equal or greater to 33% while achieving a fuel consumption 30% less with respect to the baseline control strategy in low-load drive cycles.

High electricity cost is the biggest challenge faced by the steel industry in transitioning to hydrogen based steelmaking. A steel plant in Norway could have access to cheap emission free electricity high-quality iron ore skilled manpower and the European market. An open-source model for conducting techno-economic assessment of a hydrogen based steel manufacturing plant operating in Norway has been developed in this work. Levelized cost of production (LCOP) for two plant configurations; one procuring electricity at a fixed price and the other procuring electricity from the day-ahead electricity markets with different electrolyzer capacity were analyzed. LCOP varied from $622/tls to $722/tls for the different plant configurations. Procuring electricity from the day-ahead electricity markets could reduce the LCOP by 15%. Increasing the electrolyzer capacity reduced the operational costs but increased the capital investments reducing the overall advantage. Sensitivity analysis revealed that electricity price and iron ore price are the major contributors to uncertainty for configurations with fixed electricity prices. For configurations with higher electrolyzer capacity changes in the iron ore price and parameters related to capital investment were found to affect the LCOP significantly.

The thermal efficiency and combustion of conventional hydrogen engines cannot be optimized and improved by its symmetric reciprocating. This article introduces an asymmetric motion hydrogen engine (AHE) and investigates its combustion characteristics using diesel pilot ignition. A dynamic model is firstly proposed to describe the asymmetric motion of the AHE and then it is coupled into a multidimensional model for combustion simulation. The effect of asymmetric motion on the AHE combustion is also analyzed by comparing with a corresponding conventional symmetric hydrogen engine (SHE). The results show that the AHE moves slower in compression and faster in expansion than the SHE which brings about higher hydrogen-air mixing level for combustion. The asymmetric motion delays diesel injection to ignite the AHE and its combustion appears later than the SHE which leads to lower pressure and temperature for reducing NO formation. However the AHE faster expansion has a more severe post-combustion effect to reduce isovolumetric heat release level and decrease the energy efficiency.

There is renewed interest in hydrogen as an alternative fuel for aero engines due to their perceived environmental and performance benefits compared to jet fuel. This paper presents a cycle thermal performance energy and creep life assessment of hydrogen compared with jet fuel using a turbofan aero engine. The turbofan cycle performance was simulated using a code developed by the authors that allows hydrogen and jet fuel to be selected as fuel input. The exergy assessment uses both conservations of energy and mass and the second law of thermodynamics to understand the impact of the fuels on the exergy destruction exergy efficiency waste factor ratio environmental effect factor and sustainability index for a turbofan aero engine. Finally the study looks at a top-level creep life assessment on the high-pressure turbine hot section influenced by the fuel heating values. This study shows performance (64% reduced fuel flow rate better SFC) and more extended blade life (15% increase) benefits using liquefied hydrogen fuel which corresponds with other literary work on the benefits of LH2 over jet fuel. This paper also highlights some drawbacks of hydrogen fuel based on previous research work and gives recommendations for future work aimed at maturing the hydrogen fuel concept in aviation.

Green liquid hydrogen (LH2) could play an essential role as a zero-carbon aircraft fuel to reach long-term sustainable aviation. Excluding challenges such as electrolysis transportation and use of renewable energy in setting up hydrogen (H2) fuel infrastructure this paper investigates the interface between refueling systems and aircraft and the impacts on fuel distribution at the airport. Furthermore it provides an overview of key technology design decisions for LH2 refueling procedures and their effects on the turnaround times as well as on aircraft design. Based on a comparison to Jet A-1 refueling new LH2 refueling procedures are described and evaluated. Process steps under consideration are connecting/disconnecting purging chill-down and refueling. The actual refueling flow of LH2 is limited to a simplified Reynolds term of v · d = 2.35 m2/s. A mass flow rate of 20 kg/s is reached with an inner hose diameter of 152.4 mm. The previous and subsequent processes (without refueling) require 9 min with purging and 6 min without purging. For the assessment of impacts on LH2 aircraft operation process changes on the level of ground support equipment are compared to current procedures with Jet A-1. The technical challenges at the airport for refueling trucks as well as pipeline systems and dispensers are presented. In addition to the technological solutions explosion protection as applicable safety regulations are analyzed and the overall refueling process is validated. The thermodynamic properties of LH2 as a real compressible fluid are considered to derive implications for airport-side infrastructure. The advantages and disadvantages of a subcooled liquid are evaluated and cost impacts are elaborated. Behind the airport storage tank LH2 must be cooled to at least 19 K to prevent two-phase phenomena and a mass flow reduction during distribution. Implications on LH2 aircraft design are investigated by understanding the thermodynamic properties including calculation methods for the aircraft tank volume and problems such as cavitation and two-phase flows. In conclusion the work presented shows that LH2 refueling procedure is feasible compliant with the applicable explosion protection standards and hence does not impact the turnaround procedure. A turnaround time comparison shows that refueling with LH2 in most cases takes less time than with Jet A-1. The turnaround at the airport can be performed by a fuel truck or a pipeline dispenser system without generating direct losses i.e. venting to the atmosphere.