Prospects and challenges for green hydrogen production and utilization in the Philippines

The Philippines is exploring different alternative sources of energy to make the country less dependent on imported fossil fuels and to reduce significantly the country's CO₂ emissions. Given the abundance of renewable energy potential in the country, green hydrogen from renewables is a promising fuel because it can be utilized as an energy carrier and can provide a source of clean and sustainable energy with no emissions. This paper aims to review the prospects and challenges for the potential use of green hydrogen in several production and utilization pathways in the Philippines. The study identified green hydrogen production routes from available renewable energy sources in the country, including geothermal, hydropower, wind, solar, biomass, and ocean. Opportunities for several utilization pathways include transportation, industry, utility, and energy storage. From the analysis, this study proposes a roadmap for a green hydrogen economy in the country by 2050, divided into three phases: I–green hydrogen as industrial feedstock, II–green hydrogen as fuel cell technology, and III–commercialization of green hydrogen. On the other hand, the analysis identified several challenges, including technical, economic, and social aspects, as well as the corresponding policy implications for the realization of a green hydrogen economy that can be applied in the Philippines and other developing countries.     

Hydrogen-based systems for integration of renewable energy in power systems: Achievements and perspectives

This paper is a critical review of selected real-world energy storage systems based on hydrogen, ranging from lab-scale systems to full-scale systems in continuous operation. 15 projects are presented with a critical overview of their concept and performance. A review of research related to power electronics, control systems and energy management strategies has been added to integrate the findings with outlooks usually described in separate literature. Results show that while hydrogen energy storage systems are technically feasible, they still require large cost reductions to become commercially attractive. A challenge that affects the cost per unit of energy is the low energy efficiency of some of the system components in real-world operating conditions. Due to losses in the conversion and storage processes, hydrogen energy storage systems lose anywhere between 60 and 85% of the incoming electricity with current technology. However, there are currently very few alternatives for long-term storage of electricity in power systems so the interest in hydrogen for this application remains high from both industry and academia. Additionally, it is expected that the share of intermittent renewable energy in power systems will increase in the coming decades. This could lead to technology development and cost reductions within hydrogen technology if this technology is needed to store excess renewable energy. Results from the reviewed projects indicate that the best solution from a technical viewpoint consists in hybrid systems where hydrogen is combined with short-term energy storage technologies like batteries and supercapacitors. In these hybrid systems the advantages with each storage technology can be fully exploited to maximize efficiency if the system is specifically tailored to the given situation. The disadvantage is that this will obviously increase the complexity and total cost of the energy system. Therefore, control systems and energy management strategies are important factors to achieve optimal results, both in terms of efficiency and cost. By considering the reviewed projects and evaluating operation modes and control systems, new hybrid energy systems could be tailored to fit each situation and to reduce energy losses.     

Effects of nanofluids on the photovoltaic thermal system for hydrogen production via electrolysis process

In this study the photovoltaic hybrid thermal system has been fabricated for an effective increase in production of electric output. Further the PV/T system also designed to produce the hydrogen from the water through electrolysis process. Several studies reported drastic reduction in the electric output due to high cell temperatures. Nevertheless, these effects are reduced by introduction of the nanoparticles. This study also examines the nanofluids MWCNT and Fe₂O₃ as the passive cooling agent for higher electric output production without any major energy loss. The nanoparticles are dispersed in the water at the optimum fashions to increase the thermal and electrical efficiency of the system. Both MWCNT and Fe₂O₃ nanofluids were passed to the hybrid system at the flow rate of 0.0075 kg/s and 0.01 kg/s. The highest electrical output and thermal efficiency has been obtained at 12.30 P.M. With regard to the production of hydrogen, the maximum productions were observed from 12.15 P.M. to 13.00 P.M.. Implementation of this method compensates the energy loss with superior electrical output compared to previous conventional method. By compelling the results, 0.01 kg/s subjected to be efficient on the electricity production and the hydrogen generation. Further, employing the electrolyzer as the attached to the hybrid system produces the hydrogen, which can be stored for future use as the promising source of energy.     

Analysis of hydrogen production from combined photovoltaics, wind energy and secondary hydroelectricity supply in Brazil

In this work, the technical and economical feasibility for implementing a hypothetical electrolytic hydrogen production plant, powered by electrical energy generated by alternative renewable power sources, wind and solar, and conventional hydroelectricity, was studied mainly trough the analysis of the wind and solar energy potentials for the northeast of Brazil. The hydrogen produced would be exported to countries which do not presently have significant renewable energy sources, but are willing to introduce those sources in their energy system. Hydrogen production was evaluated to be around 56.26 × 10⁶ m³ H₂/yr at a cost of 10.3 US$/kg.     

Varying load distribution impacts on the operation of a hydrogen generator plant

This study advances several methods to evaluate the operation of a hydrogen generator plant. The model developed helps customize plants that contain multiple generators of varying powers using a decision module, which determines the most efficient plant load distribution. Evaluation indices to assess individual devices within the plant are proposed and system flexibility maximizes the amount of renewable energy stored. Three case studies examined the variable load distribution of an electrolysis system connected to a 40 MW wind farm for energy storage purposes and incorporated a “night-valley” operational strategy. These methods facilitate the selection of the proper plant configuration and provide estimates for individual device effectiveness within the system.     

The viability of hydrogen storage to supplement renewable energy when used to power municipal scale reverse osmosis plant

This paper investigates the viability of using hydrogen energy storage to supplement renewable energy when used to meet a significant and fundamental human need, in this case, large-scale drinking water supplies for around 50,000 people in Newhaven, in South East England, and in Massawa in Eritrea.     

Energy and exergy analysis of a turbocharged hydrogen internal combustion engine

This paper has analyzed the energy and exergy distribution of a 2.3 L turbocharged hydrogen engine by mapping characteristics experiment. The energy loss during fuel energy conversion mainly includes: exhaust energy (23.5–34.7%), cooling medium (coolant and oil) energy (21.3–34.8%), intercooler energy (0.5–3.6%) and uncounted energy (5.8–14.1%), while the proportion of effective work ranges from 25.7% to 35.1%. Results show that all kinds of energies increase with engine speeds and they are not sensitive to the loads. However, the proportions of different kind of energy exhibit different characteristics. Moreover, the turbocharger can increase the brake thermal efficiency and the maximum can be increased by 4.8%. Exergy analysis shows exergy efficiency of the coolant energy does not exceed 5%, while the exergy efficiency of the exhaust energy can reach up to 23%. And the total hydrogen fuel thermal efficiency limit is theoretically above 59%.     

Hydrogen systems for large-scale photovoltaic plants: Simulation with forecast and real production data

The unevenness of solar photovoltaic energy output poses a number of issues that reduce its capability to be considered a reliable substitute for fossil fuels. For instance, solar photovoltaic plants convert and inject energy in the grid during the daytime, but fail to do so during bad weather conditions or at night. Variable weather conditions also render a reliable energy injection planning impossible, causing the photovoltaic power plant output to be most often unpredictable. Furthermore, all the energy converted and immediately injected in the grid poses the risk of creating imbalances in the electric energy distribution lines. A nation-wide energy system characterized by a large penetration of photovoltaic and wind energy sources can therefore be extremely difficult to manage and cannot be considered dependable. The core issue is how to improve the reliability of electricity production from such renewable energy sources.     

Size optimization of a hybrid photovoltaic/fuel cell grid connected power system including hydrogen storage

This paper describes the size optimization of a hybrid photovoltaic/fuel cell grid linked power system including hydrogen storage. The overall objective is the optimal sizing of a hybrid power system to satisfy the load demand of a university laboratory with an unreliable grid, with low energy cost and minimal carbon emissions. The aim is to shift from grid linked diesel power system to a clean and sustainable energy system. The optimum design architecture was established by adopting the energy-balance methods of HOMER (hybrid optimization model for electric renewables). Analysis of hourly simulations was performed to decide the optimal size, cost and performance of the hybrid system, using 22-years monthly averaged solar radiation data collected for Ambrose Alli University, Ekpoma (Lat. 6°44.3ʹN, Long. 6°4.8ʹE). The results showed that a hybrid system comprising 54.7 kW photovoltaic array, 7 kW fuel cell system, 14 kW power inverter and 3 kW electrolyzer with 8 kg hydrogen storage tank can sustainably augment the erratic grid with a very high renewable fraction of 96.7% at $0.0418/kWh. When compared with the conventional usage of grid/diesel generator system; energy cost saving of more than 88% and a return on investment of 41.3% with present worth of $308,965 can be derived in less than 3 years. The application of the optimally sized hybrid system would possibly help mitigate the rural-to-urban drift and resolve the electricity problems hindering the economic growth in Nigeria. Moreover, the hybrid system can alleviate CO₂ emissions from other power generation sources to make the environment cleaner and more eco-friendly.     

Cost of green hydrogen: Limitations of production from a stand-alone photovoltaic system

The aim of this work is to analyse the price of renewable hydrogen production in a stand-alone photovoltaic plant. The energy studied herein is generated in a photovoltaic plant. Two dependent parameters that directly affect the price of hydrogen are analysed in detail: the price of the electricity needed to carry out its production process, and the utilisation rate of the connected electrolyser. To this end, a photovoltaic plant is dimensioned with the help of the PVsyst simulator, by means of which the hourly generation curves are obtained. A variable power electrolyser is employed to study its performance according to these photovoltaic production curves. Furthermore, the system is studied by introducing batteries capable of storing the energy left over during the day and of supplying the electrolyser when the photovoltaic power is insufficient. The selling prices calculated in the various scenarios in terms of efficiency and electricity cost are calculated. The significance of a combined analysis of these two parameters and their real impact on the final price of hydrogen is also analysed. This article aims to analyse the price of green hydrogen produced through an isolated photovoltaic system. When the hourly production is evaluated, differences are found with respect to global production that justify the importance of the variables analysed herein, which could not be determined in any other way. The behaviour of isolated production and its effects are discussed.     

Feasibility of renewable energy storage using hydrogen in remote communities in Bhutan

This paper considers the technical and economic feasibility of using renewable energy with hydrogen as the energy storage medium for two remote communities in Bhutan, selected to illustrate two common scenarios presenting different challenges. The Royal Government of Bhutan has published plans to provide electricity to all households in the next 20 years, but the practical problems of extending the grid over long distances and mountainous terrain will make that target difficult and expensive to achieve. Consequently, the possibility of using natural energy and diversified generation is attractive. This paper examines the use of hydro power in one community and photovoltaics with wind power in another. Hydrogen is the proposed energy storage medium in both cases. Analysis suggests that it is technically possible to use renewable energy and hydrogen for diversified power supplies and that where, as here, the costs of grid extension are high, it may also be financially viable. Thus we argue that there is a good case for establishing a test and demonstration system near the capital Thimphu for further investigation prior to use in remote locations.     

Decarbonization synergies from joint planning of electricity and hydrogen production: A Texas case study

Hydrogen (H₂) shows promise as an energy carrier in contributing to emissions reductions from sectors which have been difficult to decarbonize, like industry and transportation. At the same time, flexible H₂ production via electrolysis can also support cost-effective integration of high shares of variable renewable energy (VRE) in the power system. In this work, we develop a least-cost investment planning model to co-optimize investments in electricity and H₂ infrastructure to serve electricity and H₂ demands under various low-carbon scenarios. Applying the model to a case study of Texas in 2050, we find that H₂ is produced in approximately equal amounts from electricity and natural gas under the least-cost expansion plan with a CO₂ price of $30–60/tonne. An increasing CO₂ price favors electrolysis, while increasing H₂ demand favors H₂ production from Steam Methane Reforming (SMR) of natural gas. H₂ production is found to be a cost effective solution to reduce emissions in the electric power system as it provides flexibility otherwise provided by natural gas power plants and enables high shares of VRE with less battery storage. Additionally, the availability of flexible electricity demand via electrolysis makes carbon capture and storage (CCS) deployment for SMR cost-effective at lower CO₂ prices ($90/tonne CO₂) than for power generation ($180/tonne CO₂). The total emissions attributable to H₂ production is found to be dependent on the H₂ demand. The marginal emissions from H₂ production increase with the H₂ demand for CO₂ prices less than $90/tonne CO₂, due to shift in supply from electrolysis to SMR. For a CO₂ price of $60/tonne we estimate the production weighted-average H₂ price to be between $1.30–1.66/kg across three H₂ demand scenarios. These findings indicate the importance of joint planning of electricity and H₂ infrastructure for cost-effective energy system decarbonization.     

Multi-objective optimization of batteries and hydrogen storage technologies for remote photovoltaic systems

Stand-alone photovoltaic (PV) systems comprise one of the promising electrification solutions to cover the demand of remote consumers, especially when it is coupled with a storage solution that would both increase the productivity of power plants and reduce the areas dedicated to energy production.     

Stable power supply of an independent power source for a remote island using a Hybrid Energy Storage System composed of electric and hydrogen energy storage systems

We propose a self-sustaining power supply system consisting of a “Hybrid Energy Storage System (HESS)” and renewable energy sources to ensure a stable supply of high-quality power in remote islands. The configuration of the self-sustaining power supply system that can utilize renewable energy sources effectively on remote islands where the installation area is limited is investigated. It is found that it is important to select renewable energy sources whose output power curve is close to the load curve to improve the efficiency of the system. The operation methods that can increase the cost-effectiveness of the self-sustaining power supply system are also investigated. It is clarified that it is important for increasing the cost effectiveness of the self-sustaining power supply system to operate the HESS with a smaller capacity of its components by setting upper limits on the output power of the renewable energy sources and cutting the infrequent generated power.     

Analytical model for predicting the performance of photovoltaic array coupled with a wind turbine in a stand-alone renewable energy system based on hydrogen

We present the results of an analysis of the performance of a photovoltaic array that complement the power output of a wind turbine generator in a stand-alone renewable energy system based on hydrogen production for long-term energy storage. The procedure for estimating hourly solar radiation, for a clear sunny day, from the daily average solar insolation is also given. The photovoltaic array power output and its effective contribution to the load as well as to the energy storage have been determined by using the solar radiation usability concept. The excess and deficit of electrical energy produced from the renewable energy sources, with respect to the load, govern the effective energy management of the system and dictate the operation of an electrolyser and a fuel cell generator. This performance analysis is necessary to determine the effective contribution from the photovoltaic array and the wind turbine generator and their contribution to the load as well as for energy storage.     

Renewable and hydrogen energy integrated house

The residential sector accounts for about a third of the total world energy consumption. Energy efficiency, Renewable Energy Sources and Hydrogen can play an important role in reducing the consumptions and the emissions and improving the energy security if integrated (Efficiency, Res, Hydrogen) systems are developed and experimented. The paper analyzes a real residential 100 square meters house, where energy efficiency measures and RES technologies have been applied, sizing a hydrogen system (electrolyzer, metal hydrides and fuel cell) for power backup, taking into consideration its dynamic behavior, experimentally determined. The technologies used are already available in the market and, except hydrogen technologies, sufficiently mature. Through energy efficiency technologies (insulation, absorbers, etc), the maximum electrical and thermal power needed decreases from 4.4 kW_e to 1.7 kW_e (annual consumption from 5000 kWh to 1200 kWh) and from 5.2 kW_t to 1.6 kW_t (annual consumption from 14,600 kWh to 4500 kWh) respectively. With these reduced values it has been possible to supply the consumptions entirely by small photovoltaic and solar thermal plants (less than 10 m² each). The hydrogen backup even if remains the most expensive (versus traditional batteries and gasoline generator), satisfying all the electric needs for one day, increases the security and allows net metering. Moreover the low-pressure hydrogen storage system through metal hydrides guarantees system safety too. Finally the system modularity can also satisfy higher energy production.     

Design and transient-based analysis of a power to hydrogen (P2H2) system for an off-grid zero energy building with hydrogen energy storage

In this study, zero energy building (ZEB) with four occupants in the capital and most populated city of Iran as one of the biggest greenhouse gas producers is simulated and designed to reduce Iran's greenhouse emissions. Due to the benefits of hydrogen energy and its usages, it is used as the primary energy storage of this building. Also, the thermal comfort of occupants is evaluated using the Fanger model, and domestic hot water consumption is supplied. Using hydrogen energy as energy storage of an off-grid zero energy building in Iran by considering occupant thermal comfort using the fanger model has been presented for the first time in this study. The contribution of electrolyzer and fuel cell in supplying domestic hot water is shown. For this simulation, Trnsys software is used. Using Trnsys software, the transient performance of mentioned ZEB is evaluated in a year. PV panels are used for supplying electricity consumption of the building. Excess produced electricity is converted to hydrogen and stored in the hydrogen tank when a lack of sunrays exists and electricity is required. An evacuated tube solar collector is used to produce hot water. The produced hot water will be stored in the hot water tank. For supplying the cooling load, hot water fired water-cooled absorption chiller is used. Also, a fan coil with hot water circulation and humidifier are used for heating and humidifying the building. Domestic hot water consumption of the occupants is supplied using stored hot water and rejected heat of fuel cell and the electrolyzer. The thermal comfort of occupants is evaluated using the Fanger model with MATLAB software. Results show that using 64 m² PV panel power consumption of the building is supplied without a power outage, and final hydrogen pressure tank will be higher than its initial and building will be zero energy. Required hot water of the building is provided with 75 m² evacuated tube solar collector. The HVAC system of the building provided thermal comfort during a year. The monthly average of occupant predicted mean vote (PMV) is between ?0.4 and 0.4. Their predicted percentage of dissatisfaction (PPD) is lower than 13%. Also, supplied domestic hot water (DHW) always has a temperature of 50 °C, which is a setpoint temperature of DHW. Finally, it can be concluded that using the building's rooftop area can be transformed to ZEB and reduce a significant amount of greenhouse emissions of Iran. Also, it can be concluded that fuel cell rejected heat, unlike electrolyzer, can significantly contribute to supplying domestic hot water requirements. Rejected heat of electrolyzer for heating domestic water can be ignored.     

Development,analysis and assessment of fuel cell and photovoltaic powered vehicles

This paper deals with a new hybridly powered photovoltaic- PEM fuel cell – Li-ion battery and ammonia electrolyte cell integrated system (system 2) for vehicle application and is compared to another system (system 1) that is consisting of a PEM fuel cell, photovoltaic and Li-ion battery. The paper aims to investigate the effect of adding photovoltaic to both systems and the amount of hydrogen consumption/production that could be saved/generated if it is implemented in both systems. These two systems are analyzed and assessed both energetically and exergetically. Utilizing photovoltaic arrays in system 1 is able to recover 177.78 g of hydrogen through 1 h of continuous driving at vehicle output power of 98.32 kW, which is approximately 3.55% of the hydrogen storage tank used in the proposed systems. While, using the same photovoltaics arrays, system 2 succeeds to produce 313.86 g of hydrogen utilizing the ammonia electrolyzer system 2 appeared to be more promising as it works even if the car is not in operation mode. Moreover, the hydrogen produced from the ammonia electrolyzer can be stored onboard, and the liquefied ammonia can be used as a potential source for feeding PEM fuel cell with hydrogen. Furthermore, the effects of changing various system parameters on energy and exergy efficiencies of the overall system are investigated.     

Hydrogen production and End-Uses from combined heat,hydrogen and power system by using local resources

To address the problem of fossil fuel usage at the Missouri University of Science and Technology campus, using of alternative fuels and renewable energy sources can lower energy consumption and hydrogen use. Biogas, produced by anaerobic digestion of wastewater, organic waste, agricultural waste, industrial waste, and animal by-products is a potential source of renewable energy. In this work, we have discussed Hydrogen production and End-Uses from CHHP system for the campus using local resources. Following the resource assessment study, the team selects FuelCell Energy DFC1500™ unit as a molten carbonate fuel cell to study of combined heat, hydrogen and power (CHHP) system based on a molten carbonate fuel cell fed by biogas produced by anaerobic digestion. The CHHP system provides approximately 650 kg/day. The total hydrogen usage 123 kg/day on the university campus including personal transportation applications, backup power applications, portable power applications, and other mobility applications are 56, 16, 29, 17, and 5 respectively. The excess hydrogen could be sold to a gas retailer. In conclusion, the CHHP system will be able to reduce fossil fuel usage, greenhouse gas emissions and hydrogen generated is used to power different applications on the university campus.