Green hydrogen-based pathways and alternatives: Towards the renewable energy transition in South America's regions–Part B

Hydropower compounds most of the energy matrix of the countries of the Latin America and Caribbean region (LAC). Considering the concern in reducing Green House Gases emissions (GHG) from hydropower plants and hydrogen production from fossil sources, green hydrogen (H₂) appears as an energy vector able to mitigate this impact. Improving the efficiency of the plant and producing renewable energy the element is an interesting alternative from the ecological and economic point of view. This study aims to estimate the potential of H₂ production from wasted energy, through the electrolysis of water in hydroelectric plants in Colombia and Venezuela. The construction of two scenarios allowed obtaining a difference, considering a spilled flow of 2/3 in the first scenario and 1/3 in the second. In Colombia, hydrogen production reached 3.39 E+08 Nm³ at a cost of 2.05 E+05 USD/kWh in scenario1, and 1.70 E+08 Nm³ costing 4.10 E+05 USD/kWh in scenario 2. Regarding the Venezuelan context, the country obtained lower production values of H₂, ranging between 7.76 E+07 Nm³.d^?1 and 4.31 E+07 Nm³.d^?1, and production cost between 9.45 E+09 USD/kWh and 1.89 E+10 USD/kWh. Thus, the final cost for the production and storage of H₂ was estimated at 0.2239 USD.kg^?1. Ultimately, Colombia and Venezuela have a large potential to supply the demand for nitrogen fertilizers with green ammonia production, apply green hydrogen in manufacturing and use the surplus for energy substitution of Liquefied Petroleum Gas - LPG. In Colombia, the chemical energy offered is equivalent to 6.681 E+11 MJ/year^?1 and in Venezuela, the result is equal to 1.697 E+11 MJ/year^?1 in the conservative scenario. Finally, the countries have great potential for the diversification of the energy matrix and the insertion of renewables in the system.     

Integration of renewable energies using the surplus capacity of wind farms to generate H2 and electricity in Brazil and in the Rio Grande do Sul state: energy planning and avoided emissions within a circular economy

Hydrogen is a clean fuel capable of promoting sustainable energy development. The effective use of surplus energy from wind plants appears as a promising method to produce hydrogen. Accumulating surplus energy through hydrogen production and storage can solve the problem of energy excess, making energy available on-demand. This article explored the potential of hydrogen production from wind energy in three distinct scenarios of surplus energy, and the amount of electricity generation for Brazil and its regions. To a scenario of 6-h of energy excess, the potential for hydrogen production from wind energy was equal to 1.48E + 07 Nm³.d⁻¹. The state of Rio Grande do Sul reached a potential of 1.10E+06 MWh.month-¹ of electricity generation using H₂. Taking into account a payback-time of 3.5 years, the cost of hydrogen production was 0.402 US$.kWh⁻¹. Hydrogen ensures greater energy security in times of energy shortages through biofuel storage. The main goal was to show the possibilities of diversifying the national electrical matrix and the wind resources contribution to the Circular and H₂ Economy in the country.     

The potential and economic viability of hydrogen production from the use of hydroelectric and wind farms surplus energy in Brazil: A national and pioneering analysis

Energy security is an issue at stake in governments all over the world, and also in Brazil. Although the country's energetic matrix is largely based on hydropower sources, the need for diversification is increasingly needed. The possibility of hybrids between hydropower and wind power for hydrogen production emerges as a clean alternative source for energy security. In high-throughput seasons, excess energy could be used to produce hydrogen, which could supply shortages of energy. This study shows the potential for producing hydrogen in Brazil, using excess energy from hydroelectric and wind farms. Taking into account one hour per day of surplus energy production, it would be possible to generate 6.50E+09 Nm³.y⁻¹ of H₂. On the other hand, considering two and three hours, the H₂ generation would be equal to 1.30E+10 Nm³.y⁻¹ and 2.00E+10 Nm³.y⁻¹, respectively. This study calculated the economic viability for hydrogen production, at a cost of 0.303 USD.kWh⁻¹, a higher cost if compared to that of the wind and hydroelectric plants.     

An assessment of solar hydrogen production using the mark 13 hybrid process

An assessment is presented of hydrogen production using a dedicated central solar receiver system concept coupled to a Mark 13-V2 hybrid thermochemical process. The system which is capable of producing about 10⁶ GJ hydrogen per year was developed at the conceptual level. The total irradiance at normal incidence was taken as a parameter and varied from 1500 to 2500 kWh m^?2 y^?1 at a location with 30° latitude and 0.1 km altitude. The peak noon irradiance at normal incidence was taken as 0.95 kW m^?2 and the mean total sunshine hours as 2333 h y^?1.A flow sheet of the solar Mark 13-V2 hybrid process was developed to operate using the intermittent heat supply from the central receiver system and the continuous electric energy supply from outside. It was then evaluated using the models for the central receiver system, the solar receiver and the chemical process.It is found that for 2000 kWh m^?2 y^?1 total irradiance at normal incidence, the overall efficiency of the solar Mark 13-V2 process is about 21% and that the cost of the solar hydrogen is about $52 GJ^?1.     

A mathematical,economic and energetic appraisal of biomethane and biohydrogen production from Brazilian ethanol plants' waste: Towards a circular and renewable energy development

The high production of sugarcane in Brazil and its application of ethanol and sugar production results in a higher generation of vinasse and bagasse. The treatment of these residues can be carried out using anaerobic co-digestion procedures. Besides promoting waste treatment, it enables energy exploration through biogas and hydrogen generation. Bioenergy use can also generate steam in sugar and alcohol plants by burning, sugarcane milling, fueling vehicles for the transport of products, among others. These energy applications allow total and efficient, energetic exploring of sugarcane. Hence, this study estimated the production of methane, hydrogen, thermal and electrical energy generated from vinasse and bagasse in the autonomous and annexed Brazilian ethanol and sugar plants. Three scenarios present the use of biogas generated: Scenario 1: energy use of all methane from biogas; Scenario 2: hydrogen production from the remaining methane, after considering the energy autonomy of the ethanol plants; Scenario 3: hydrogen production from all the methane generated. All the scenarios which considered the use of methane led to energy self-sufficiency in the sector. However, only annexed plants present economic feasibility for implementing the project. Scenario 2 is highlighted in this study, once beyond the sector's energetic self-sufficiency, the operational conditions enabled the storage of 9.26E+07 Nm³.d^?1 of hydrogen, equal 3.04E+08 ton per year. CH₄ and H₂ production seen in a global scenario of circular economy and energy security have high benefits, contributing to the gradual transformation of an economy dependent on non-renewable resources into a circular and renewable economy.     

A pioneering study of biomethane and hydrogen production from the wine industry in Brazil: Pollutant emissions,electricity generation and urban bus fleet supply

The thematic area studied in this paper considers environmental issues such as atmospheric pollution from the combustion of fossil fuels, and the environmental impacts from the generation of urban agricultural solid wastes. This study has estimated the potential for hydrogen and biogas production from solid urban waste (SUW) and wine waste from Bento Gonçalves, which is a region in Brazil with the largest wine throughput and subsequent waste generation, thus providing a potential high-energy feedstock. The resulting hydrogen and biogas are assumed to displace the existing fuels in the local bus fleet. The analytical work consisted of three scenarios - scenario 1: production of biogas using SUW, sourced exclusively from the municipality of Bento Gonçalves; Scenario 2: the possibility to supply SUW from Bento Gonçalves and surrounding cities, to produce biogas; Scenario 3: the possibility to use wine waste and SUW for biogas production. Scenario 3 showed the greatest energy yield with 37.9 Gg of biomethane produced per year, which can supply the entire public bus fleet of Bento Gonçalves. The resulting hydrogen production potential using steam reforming of biomethane is 1.09 E+08 Nm³H₂.d^?1 which can generate 2.62 TW h.year^?1 of electrical energy, avoiding approximate emissions of 355 ktonCO₂.year^?1. These findings indicate value in the production of biogas from urban and agricultural wastes, especially for the generation of methane, hydrogen and useful energy outputs. Its production from renewable and clean sources contributes to the gradual transformation of an economy currently dependent on non-renewable resources into a circular and renewable economy.     

Transient simulation and comparative assessment of a hydrogen production and storage system with solar and wind energy using TRNSYS

This paper uses the TRNSYS software to investigate the hourly energy generation potential, storage, and consumption via an electrolyzer and a fuel cell in the Canadian city of Saskatoon, which is a region with high solar and wind energy potential. For this purpose, a location with an area of 10,000 m² was considered, in which the use of solar panels and vertical-axis wind turbines (VAWTs) were simulated. In the simulation, the solar panels were placed at specific distances, and the energy generation capacity, amount of produced hydrogen, and the energy available from the fuel cell were examined hourly and compared to the case with wind turbines placed at standard distances. The results indicated energy generation capacities of 1,966,084 kWh and 75,900 kWh for the solar panels and the wind turbines, respectively, showing the high potential of solar panels compared to wind turbines. Moreover, the fuel cells in the solar and wind systems can produce 733,077 kWh and 22,629 kWh of energy per year, respectively, if they store all of the received energy in the form of hydrogen. Finally, the hourly rates of hydrogen production by the solar and wind systems were reported.     

Theoretical analysis of green hydrogen from hydropower: A case study of the Northwest Columbia River system

Within the Pacific Northwest region of the United States, there is the unique opportunity to explore alternative energy management solutions of the Columbia River's multi-use hydropower system. As with various European hydropower systems that experience large variability in water runoff, but lack adequate reservoir storage capacity, the Columbia River System is a viable source for renewable hydrogen production. This paper studies the theoretical potential of green hydrogen production from excess hydropower energy from the Columbia River System. The potential surplus hydroelectric energy and hydrogen production potential from surplus energy (during March through July months) are estimated from 11 hydroelectric projects along with the Columbia River System. Results show that the system's total monthly average hydrogen production potential ranges from 2.22 × 10⁶ to 8.96 × 10⁶ kg H₂ with the utilization of surplus energy over a historical 80 water year period (1928–2008). This study concludes that hydrogen production from spilled hydropower energy and its use in the transportation sector is a viable opportunity to lead the country towards a hydrogen economy.     

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.     

Highly-stable,bifunctional, binder-free & stand-alone photoelectrode (FexNi1-xO@a-CC) for natural waters splitting into hydrogen

Photoelectrochemical (PEC) water splitting is a promising approach to boost green hydrogen production. Herein, we prepared novel binder-free photoelectrode by direct growth of iron doped nickel oxide catalyst over activated carbon cloth (Fe_xNi_1-xO@a-CC) having band gap energy of 2.2 eV for overall water splitting. Fe_xNi_1-xO@a-CC photoelectrode had shown remarkable lower potential of only 1.36 V for oxygen evolution reaction (OER) to reach 10 mA cm^?2 current density using very low photonic intensity of 8.36 × 10^?4 E/L.s. For the first time, we also reported electrical efficiency required for PEC water splitting for 1 m³ of water that is equal to 0.09 kWh/m³. Fe_xNi_1-xO@a-CC photoelectrode also exhibits low potentials of 1.44 V (OER) and ?0.210 V (HER) at 10 mA cm^?2 to split sea water. Our results confirmed that designing Fe_xNi_1-xO@a-CC photoelectrode would be an innovative step to widen green energy conversion applications using natural waters (both sea and fresh water).     

Experimental investigation of solar assisted hydrogen production from water and aluminum

Sustainable production of hydrogen at high capacities and low costs is one the main challenges of hydrogen as a future alternative fuel. In this paper, a new hydrogen production system is designed and fabricated to investigate hydrogen production using aluminum and solar energy. Numerous experiments are performed to evaluate the hydrogen production rate, quantitatively and qualitatively. Moreover, correlations between the total hydrogen production volume over time and other parameters are developed and the energy efficiency and conversion ratio of the system are determined. Also, a method is developed to obtain an optimal and stable hydrogen production rate based on system scale and consumed materials. It is observed that at low temperatures, the hydrogen production volume, efficiency and COP of the system increase at a higher sodium hydroxide molarity. In contrast, at high temperatures the results are vice versa. The maximum hydrogen production volume, hydrogen production rate, reactor COP and system efficiency using 0.5 M NaOH solution containing 3.33 g lit^?1 aluminum at 30 °C are 6119 mL, 420 mL min^?1, 1261 mL H₂ per 1 g of Al, and 16%, respectively.     

On the reduction of electric energy consumption in electrolysis: A thermodynamic study

Electricity is the major component in the cost of hydrogen production via electrolysis. This study aims to reduce electric energy consumption in electrolysis and replace it with lower cost thermal energy. An idealized thermodynamic analysis of hydrogen production by electrolysis at higher temperatures is presented, with particular emphasis on isolating the work and thermal components of the required energy. There is significant advantage in using thermal energy from another complementary process to overheat the inlet steam to meet this need. The electricity demand for electrolysis, under reasonable conditions, can thus be reduced to 26.63 kWh kg^?1. Introducing multiple stages can further reduce this to 25.22 kWh kg^?1 and more significantly, greatly reduce the temperature of the thermal energy needed. At lower utilizations, it is possible to reduce the electrical requirement to below 20 kWh kg^?1, which is less than half the most aggressive targets for electrolyzer improvements.     

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.     

Producing hydrogen from the fermentation of cheese whey and glycerol as cosubstrates in an anaerobic fluidized bed reactor

This study aimed to evaluate the effect of the organic loading rate (OLR) (60, 90, and 120 g Chemical Oxygen Demand (COD). L^?1. d^?1) on hydrogen production from cheese whey and glycerol fermentation as cosubstrates (50% cheese whey and 50% glycerol on a COD basis) in a thermophilic fluidized bed reactor (55 °C). The increase in the OLR to 90 gCOD.L^?1. d^?1 favored the hydrogen production rate (HPR) (3.9 L H₂. L^?1. d^?1) and hydrogen yield (HY) (1.7 mmol H₂. gCOD^?1_app) concomitant with the production of butyric and acetic acids. Employing 16S rRNA gene sequencing, the highest hydrogen production was related to the detection of Thermoanaerobacterium (34.9%), Pseudomonas (14.5%), and Clostridium (4.7%). Conversely, at 120 gCOD.L^?1. d^?1, HPR and HY decreased to 2.5 L H₂. L^?1. d^?1 and 0.8 mmol H₂. gCOD^?1_app, respectively, due to lactic acid production that was related to the genera Thermoanaerobacterium (50.91%) and Tumebacillus (23.56%). Cofermentation favored hydrogen production at higher OLRs than cheese whey single fermentation.     

Techno-economic analysis of a hybrid energy system for CCHP and hydrogen production based on solar energy

A typical problem in Northeast China is that a large amount of surplus electricity has arisen owing to the serious photovoltaic power curtailment phenomenon. To effectively utilize the excess photovoltaic power, a hybrid energy system is proposed that uses surplus electricity to produce hydrogen in this paper. It combines solar energy, hydrogen production system, and Combined Cooling Heating and Power (CCHP) system to realize cooling, heating, power, and hydrogen generation. The system supplies energy for three public buildings in Dalian City, Liaoning Province, China, and the system configuration with the lowest unit energy cost (0.0615$/kWh) was obtained via optimization. Two comparison strategies were used to evaluate the hybrid energy system in terms of unit energy cost, annual total cost, fossil energy consumption, and carbon dioxide emissions. Subsequently, the annual total energy supply, typical daily loads, and cost of the optimized system were analyzed. In conclusion, the system is feasible for small area public buildings, and provides a solution to solve the phenomenon of photovoltaic power curtailment.     

Green hydrogen-based pathways and alternatives: Towards the renewable energy transition in South America's regions – Part A

In recent years, there has been an increased concern regarding the impacts of climate change caused by the increase in anthropogenic CO₂ emissions, and the search for clean energy sources has grown. Hydrogen produced from renewable sources is an alternative to the demand for clean energy. Argentina, Paraguay and Uruguay are countries located in South America with a considerable number of rivers and hydroelectric plants. This study shows the potential production of hydrogen in these countries using the excess energy from hydroelectric plants. While Argentina has a potential generation of 3.44E+10 Kg.year^?1 of H₂, Paraguay and Uruguay presented, respectively, 5.32E+10 Kg.year^?1 and 2.19E+10 Kg.year^?1. Taking into account the economic viability analysis, H production and storage had a profit of 0.2253 US$.m^?3 for Paraguay, 0.2249 US$.m^?3 for Uruguay and a cost of 0.2263 US$.m^?3 in Argentina. The results of this research contribute to the renewable, sustainable energy transition and in accordance with the precepts of the circular economy for the search for new sources of energy. This idea needs to be encouraged around the world, including developing countries.     

Off-grid solar photovoltaic-alkaline electrolysis-metal hydrogen storage-fuel cell system: An investigation for application in eco-neighborhood in Ningbo,China

This study proposes a combined hydrogen, heating and power system based on solar energy for the off-grid application of distributed renewable energy. With hydrogen as the energy carrier, the stable consumption of renewable energy can be achieved by integrating alkaline water electrolysis (AWE), metal hydride (MH) hydrogen storage, and proton exchange membrane fuel cells (PEMFCs). An energy management strategy is proposed based on the coordinated control of mass, energy, and information flow. Fluctuations in multi-source heat flow during solar photovoltaic (PV) power generation, hydrogen production, hydrogen-storage, and PEMFC power generation were studied based on electric and heating loads of typical winter and summer days in an eco-neighborhood in Ningbo, China. Owing to differences in solar radiation between summer and winter, the total electric energy generated by PV panels was 6179 kWh and 3667 kWh for summer and winter, respectively. The start-up times for AWE and MHs were 0.92 h and 0.32 h in summer and 1.70 h and 0.55 h in winter, respectively. After one day of operation, the hydrogen and heat surpluses were 57.17 kg and 5735.83 MJ in summer, while in winter the hydrogen surplus and heat deficit were 30.87 kg and 226.41 MJ, respectively.     

An effective method for hydrogen production in a single-chamber microbial electrolysis by negative pressure control

In this study, we construct a scalable tubular single-chamber microbial electrolysis cell that using negative pressure (40.52 kPa) to enhance the hydrogen production. The impact of negative pressure on current production, hydrogen recovery, and microbial community of microbial electrolysis cells are investigated. Negative pressure could effectively enhance the hydrogen recovery and inhibit the growth of methanogens. Consequently, the microbial electrolysis cell operated under negative pressure achieves a maximum hydrogen production rate of 7.72 ± 0.06 L L^?1 d^?1, which is more than four times higher that of reactor running under normal pressure (1.51 ± 0.41 L L^?1 d^?1). Energy quantification shows that the electrical energy recovery under negative pressure is 146.98%, which is much higher than 95.00% under normal pressure. Therefore, negative pressure control is as effective for increasing hydrogen production and energy recovery in the scalable MEC, and has a great practical application prospect. However, negative pressure cannot knick out methanogens. Once negative pressure is removed, methanogens will quickly take over and after that applying negative pressure again can only partly inhibit methane production.     

Solar hydrogen production in urban areas of Mexico: towards hydrogen cities

Many efforts have been made to assess the potential of green hydrogen production at global, regional, and national levels using Geographic Information Systems (GIS); however, many dismiss the possibility of producing hydrogen in urban settlements. In order to reveal the true potential of these areas, it is essential to provide arguments that allow evaluation of the feasibility of promoting and impulsing the concept of hydrogen cities. Based on this idea, this work assesses the monthly and annual potential of solar hydrogen in urban areas of Mexico using actual measurements of sunshine duration as electrolyzer production times. Moreover, as light transportation is crucial for cities, we examine the substitution of gasoline with hydrogen and its cost throughout the year. These constitute the main contribution of the present work.This study departs from the geographical and technical potential of solar energy, and by using GIS, the amount of hydrogen production per unit of area (Ton/(km² year)) was computed. The levelized cost of hydrogen production (LCOH) is also evaluated, using two of the most popular and commercial electrolysis technologies: PEM and Alkaline.Our results revealed that Mexican urban areas have a high potential to produce solar hydrogen, having an average annual production that varies from 1991.8 Ton/km² to 4338.3 Ton/km² according to the region. The total solar hydrogen potential of all Mexican urban places is 9.39 MTon/year, which could satisfy up to 42.6 times the 2020 hydrogen demand of Mexico. We found that the national gasoline consumption could be replaced by H₂, requiring between 42% and 52% of the total urban production.Additionally, the national average of LCOH was found to be about 6.25 USD/kg for alkaline electrolyzer and 9.50 USD/kg for PEM technology, considering the yearly average sunshine duration of 3237 h/year, which means that Mexico could be competitive at large-scale hydrogen production by using Alkaline technology. Our findings have the potential to impact positively on the country since they provide information to facilitate the derivation of public policies from a rigorous and technical perspective.     

The feasibility of using geothermal energy in hydrogen production

A feasibility study exploring the use of geothermal energy in hydrogen production is presented. It is possible to use a thermal energy to supply heat for high temperature electrolysis and thereby substitute a part of the relatively expensive electricity needed. A newly developed HOT ELLY high temperature steam electrolysis process operates at 800 – 1000°C. Geothermal fluid is used to heat fresh water up to 200°C steam. The steam is further heated to 900°C by utilising heat produced within the electrolyser. The electrical power of this process is reduced from 4.6 kWh per normalised cubic meter of hydrogen (kWh/Nm³ H₂) for conventional process to 3.2 kWh/Nm³ H₂ for the HOT ELLY process implying electrical energy reduction of 29.5%. The geothermal energy needed in the process is 0.5 kWh/Nm³ H₂. Price of geothermal energy is approximately 8–10% of electrical energy and therefore a substantial reduction of production cost of hydrogen can be achieved this way. It will be shown that using HOT ELLY process with geothermal steam at 200°C reduces the production cost by approximately 19%.