A review on critical assessment of advanced bioreactor options for sustainable hydrogen production

The utilization of fossil fuels causes adverse effects on the human and environment and the world is facing the depletion of these resources. The conventional technologies available for hydrogen production create greenhouse gases which cause a serious threat to the surroundings. Hence, there is a need to create a renewable and alternative technique for hydrogen production. The biological method acts as renewable technology to conventional technologies. For the present and future generations, the development of bioreactors may provide a sustainable route to meet cleaner hydrogen production. The conventional methods like reforming process, gasification process, thermochemical method, water electrolysis and photoelectrochemical method are not sustainable which emits toxic gases and requires a large amount of energy but in the application of bioreactors the cleaner fuel can be obtained and wastewater can be treated efficiently. The objectives of this review are to estimate the efficiency of reactors involving dark fermentation reactors (suspended and attached growth reactors), photobioreactors (tubular and flat plate reactors) and microbial electrolysis cell bioreactors along with their recent advancements in hydrogen production. This article also highlighted the comprehensive review about the substrate utilization, waste treatment, the principle of reactor process and recent process developments. Although several methods are available for hydrogen production, important and innovative discoveries and process configurations in pilot-scale are needed to estimate the potential of each bioreactor to provide sustainable and cleaner fuel production. Through this review, the present status of bioreactors in hydrogen production and their scale-up opportunities can be determined.     

Hydropower for green hydrogen production in Turkey

The current study develops a hydro-based hydrogen production concept and investigates the utilization of hydroelectric power for green hydrogen production in Turkey. For the hydroelectric power potential calculations, the installed and under construction hydroelectric power plants, run-of-river systems, and reservoir dams are considered for the entire country. The potential capacities of each city are estimated based on the available official and published data by the government agencies, and some reasonable assumptions are also made for detailed analysis and assessment for a feasible hydrogen economy in the country. The results obtained here clearly show that the contribution of hydroelectric energy to hydrogen production is considerable high in promoting countries towards leadership in the field of green hydrogen production. Based on the analysis results, Turkey's hydro-based green hydrogen production potential is estimated to be 2.26 megatons. Şanlıurfa, Elazığ, Diyarbakır, Artvin, and Adana are cities with the highest green hydrogen production potential from hydroelectric power with an annual production capacity of 233.09, 204.92, 175.35, 157.28, and 140.8 kilotons, respectively. The results of this study are expected to help the policymakers to use hydropower energy for planning and developing action plan for the country and help overcome carbon-based fuel usage and its associated pollution. The main idea is to prepare hydrogen maps in detail for each region in Turkey, based on the hydro energy potential by using electrolysers. This, in turn, can be considered in the context of the current policies of the local communities and policymakers to prepare a sustainable energy roadmap for the country.     

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.     

Key prospects and major development of hydrogen and bioethanol production

Cheap Production of bioethanol from renewable lignocellulosic waste has the imperative potential to economically cut burgeoning world dependency on fossils while reducing net emission of carbon dioxide (CO₂), a principal greenhouse gas (GHGs). This paper highlights key benefits and status of bioethanol production technologies, aiming mainly on recent developments and its key potentials in Pakistan. Most sector of Pakistan economy heavily rely on the energy and power that is being produced using traditional approaches like from oil and hydel. However, the sedimentation in dams cut-down the energy generation and overwhelmed severe energy crisis that are witnessed since last decade. Thus, Pakistan must go to avail alternative sources of energy like hydro, biomass and solar so that energy security can be ensured to recover the tremendous loss of economy. Renewable biomass is abundantly available in Pakistan which can be used to produce bioethanol and electricity. Currently, 22 distilleries are producing the ethanol from sugar cane bagasse and out of these only 8 distillation units are producing motor fuel grade ethanol. The current bioethanol production of country is about 403,500 tons/year along with 2423 tons of biodegradable waste available in major cities. In addition, Pakistan produces 6.57, 0.5, 0.66, and 2.66 million tons of sugarcane, corn, rice, and wheat straw per annum, respectively. This biomass can produce 1.6 million liters of bioethanol which can produce approximately 38% of Pakistan's electricity annually. Despite having large potential, Pakistan is still producing a few volumes of ethanol from sugarcane bagasse. The production of bioethanol can be boosted using (I) pretreatment of agricultural biomass by alkali (II) enzymatic and bacteria-based hydrolysis of the biomass (III) post-hydrolysis using pressurized steam above 100 °C (IV) Fermentation of the biomass@ 7–10 h and (V) and (VI) distillation of bioethanol. This study recommends (1) increase R&D capacities mainly in the west and central regions of Pakistan, (2) initiate mega-projects to promote integrated bio-ethanol production at agriculture farms by providing 1/3 subsides, (3) purchase of bioethanol directly from the major agricultural farms, (4) produce bioethanol related manpower from the key research institutes as specified in this study.     

Design of a novel flat-plate photobioreactor system for green algal hydrogen production

Some green microalgae have the ability to harness sunlight to photosynthetically produce molecular hydrogen from water. This renewable, carbon-neutral process has the additional benefit of sequestering carbon dioxide and accumulating biomass during the algal growth phase. We document the details of a novel one-litre vertical flat-plate photobioreactor that has been designed to facilitate green algal hydrogen production at the laboratory scale. Coherent, non-heating illumination is provided by a panel of cool-white light-emitting diodes. The reactor body consists of two compartments constructed from transparent polymethyl methacrylate sheets. The primary compartment holds the algal culture, which is agitated by means of a recirculating gas-lift. The secondary compartment is used to control the temperature of the system and the wavelength of radiation. The reactor is fitted with probe sensors that monitor the pH, dissolved oxygen, temperature and optical thickness of the algal culture. A membrane-inlet mass spectrometry system has been developed and incorporated into the reactor for dissolved hydrogen measurement and collection. The reactor is hydrogen-tight, modular and fully autoclaveable.     

Resource assessment for green hydrogen production in Kazakhstan

Kazakhstan has long been regarded as a major exporter of fossil fuel energy. As the global energy sector is undergoing an unprecedented transition to low-carbon solutions, new emerging energy technologies, such as hydrogen production, require more different resource bases than present energy technologies. Kazakhstan needs to consider whether it has enough resources to stay competitive in energy markets undergoing an energy transition. Green hydrogen can be made from water electrolysis powered by low-carbon electricity sources such as wind turbines and solar panels. We provided the first resource assessment for green hydrogen production in Kazakhstan by focusing on three essential resources: water, renewable electricity, and critical raw materials. Our estimations showed that with the current plan of Kazakhstan to keep its water budget constant in the future, producing 2–10 Mt green hydrogen would require reducing the water use of industry in Kazakhstan by 0.6–3% or 0.036–0.18 km³/year. This could be implemented by increasing the share of renewables in electricity generation and phasing out some of the water- and carbon-intensive industries. Renewable electricity potential in South and West Kazakhstan is sufficient to run electrolyzers up to 5700 and 1600 h/year for wind turbines and solar panels, respectively. In our base case scenario, 5 Mt green hydrogen production would require 50 GW solar and 67 GW wind capacity, considering Kazakhstan's wind and solar capacity factors. This could convert into 28,652 tons of nickel, 15,832 tons of titanium, and many other critical raw materials. Although our estimations for critical raw materials were based on limited geological data, Kazakhstan has access to the most critical raw materials to support original equipment manufacturers of low-carbon technologies in Kazakhstan and other countries. As new geologic exploration kicks off in Kazakhstan, it is expected that more deposits of critical raw materials will be discovered to respond to their potential future needs for green hydrogen production.     

Contribution of green energy sources to electrical power production of Turkey: A review

Green power products may be seen as a means of fostering renewable energy sources (RES) because they create and channel consumer demand for environmentally sound power generation. Turkey also has a large potential for renewable energy exploitation in a number of areas. Clean, domestic and renewable energy is commonly accepted as the key for future life, not only for Turkey but also for the world. The renewable energy contribution in the total primary energy production is insignificant. The alternative and renewable energy systems have been neglected so far in Turkey but must be included in the new energy programs. In this context, Renewable Energy Law was enacted in 2005 in order to encourage renewable-based generation in competitive market conditions. Supporting mechanisms such as feed-in tariffs and purchase obligation are defined in the law, in conformity with the EU legislation and practice. These mechanisms are envisaged to facilitate the development of power plants based on RES.     

Influence of renewable energy power fluctuations on water electrolysis for green hydrogen production

The development of renewable energy technologies is essential to achieve carbon neutrality. Hydrogen can be stably stored and transported in large quantities to maximize power utilization. Detailed understanding of the characteristics and operating methods of water electrolysis technologies, in which naturally intermittent fluctuating power is used directly, is required for green hydrogen production, because fluctuating power-driven water electrolysis processes significantly differ from industrial water electrolysis processes driven by steady grid power. Thus, it is necessary to overcome several issues related to the direct use of fluctuating power. This article reviews the characteristics of fluctuating power and its generation as well as the current status and issues related to the operation conditions, water electrolyzer configuration, system requirements, stack/catalyst durability, and degradation mechanisms under the direct use of fluctuating power sources. It also provides an accelerated degradation test protocol method for fair catalyst performance comparison and share of effective design directions. Finally, it discusses potential challenges and recommendations for further improvements in water electrolyzer components and systems suitable for practical use, suggesting that a breakthrough could be realized toward the achievement of a sustainable hydrogen-based society.     

Prospects for the production of green hydrogen: Review of countries with high potential

The article provides a review of the current hydrogen production and the prospects for the development of the production of “green” hydrogen using renewable energy sources in various countries of the world that are leaders in this field. The potential of hydrogen energy in such countries and regions as Australia, the European Union, India, Canada, China, the Russian Federation, United States of America, South Korea, the Republic of South Africa, Japan and the northern countries of Africa is considered. These countries have significant potential for the production of hydrogen and “green” hydrogen, in particular through mining of fossil fuels and the use of renewable energy sources. The quantitative indicators of the production of “green” hydrogen in the future and the direction of its export are considered; the most developed hydrogen technologies in these countries are presented. The production of “green” hydrogen in most countries is the way to transition from the consumption of fossil fuels to the clean energy of the future, which will significantly improve the environmental situation, reduce greenhouse gas emissions and improve the energy independence of the regions.     

Co-firing biomass with coal for electricity generation—An assessment of the potential in EU27

The European Union aims to increase bioenergy use. Co-firing biomass with coal represents an attractive near-term option for electricity generation from renewable energy sources (RES-E). This study assesses the near-term technical potential for biomass co-firing with coal in the existing coal-fired power plant infrastructure in the EU27 Member States. The total technical potential for RES-E from biomass co-firing amounts to approximately 50–90 TWh/yr, which requires a biomass supply of approximately 500–900 PJ/yr. The estimated co-firing potential in EU27 amounts to 20–35% of the estimated gap between current RES-E production and the RES-E target for 2010. However, for some member states the national co-firing potential is large enough to fill the national gap. The national biomass supply potential is considerably larger than the estimated biomass demand for co-firing for all member states. About 45% of the estimated biomass demand for co-firing comes from plants located close to the sea or near main navigable rivers and indicates the possibility for biomass import by sea transport. Thus, biomass co-firing has the potential to contribute substantially to the RES-E development in EU27.     

Techno-economic calculation of green hydrogen production and export from Colombia

In the present paper a techno-economic hydrogen production and transportation costs to export from Colombia to Europe and Asia were determined using the open-source Python tools, such as WindPowerLIB, PVLIB, ERA5 weather data, and the Hydrogen-2-Central (H2C) model. Calculations were performed as well for Chile, for comparison as a regional competitor. In addition, a detailed overview of Colombia's energy system and national efforts for a market ramp-up of renewable energy and hydrogen is provided. The application of the model in different scenarios shows Colombia's potential to produce green hydrogen using renewable energies. The prices estimated are 1.5 and 1.02 USD/kgH₂ for 2030 and 2050 with wind power, and 3.24 and 1.65 USD/kgH₂ for 2030 and 2050 using solar energy. Colombia can become one of the most promising hydrogen suppliers to Asian and European countries with one of the lowest prices in the production and transportation of green hydrogen.     

Impacts of low harm fracturing fluid on fossil hydrogen energy production in tight reservoirs

The polymer fracturing fluid has been gradually used in the fossil hydrogen energy field. However, its impacts on the fields are still unclear. In this study, a series of experiments were conducted to solve the problem. First, a new method called the pressure transmission test (PTT) was used to evaluate the permeability damage induced by polymer fracturing fluid. Then several rock properties were tested to reveal rock potential damage induced by the aqueous fracturing fluid, after that the interactions between polymer fracturing fluid and rock were discussed in detail. Results showed that the average permeability pollution is 10.6. Permeability and X-ray diffraction (XRD) tests stated that the core is easier to be blocked by particles in the formation or fracturing fluid residue. Blocking and scanning electron microscope (SEM) tests showed that the nanoscale polymer would stick on the rock surface, and reduce the pore size. Our work provides a new method to evaluate the impact of polymer fracturing fluid on tight reservoirs. Moreover, the mechanism of permeability damage caused by the polymer fracturing fluid was also revealed.     

Insights on performance and an improved model for full scale electrolysers based on plant data for design and operation of hydrogen production

Developers and operators of energy systems based on renewable energy require effective models of these systems, including those with hydrogen storage where electrolysers are critical components. However, electrolyser models are often either too detailed to be computationally efficient within whole system model, or too inaccurate at times of low production of renewable energy. Our novel model addresses this by combining the Tafel equation and an original model for Faradaic efficiency. It was validated and tested on plant data from the 250 kW electrolyser at Bright Green Hydrogen's Levenmouth Community Energy Project in Methil, Scotland. The model estimated hydrogen consumption more accurately than the ‘Linear Model’ habitually used in industry. Our data also emphasized the importance of an optimised control scheme for minimizing hot standby losses. Pressurisation during start-up, purging and pressure-driven fluctuations also contributed significant losses and scatter when inspecting minute-by-minute data. This knowledge should inform whole system analysis and control.     

Overview of US patents for energy management of renewable energy systems with hydrogen

The problems of energy shortage, severe pollution, and global warming are becoming increasingly severe. Renewable energy systems with hydrogen have been widely used. In recent years, much literature has described the energy management of renewable energy systems with hydrogen in a comprehensive way. However, most of them are proposed and discussed from an academic point of view. There are likewise several different approaches and ideas in the patents that address the energy management of hydrogen renewable energy systems. Moreover, most patents are oriented toward industrial applications and still need to be reviewed and analyzed. To fill this gap, this paper reviews relevant US patents to find potential and industrial hydrogen applications and energy management strategies in renewable energy systems. The work presented in this paper will provide solutions and guidance in solving energy management problems in renewable energy systems.     

Life cycle assessment of alternatives for hydrogen production from renewable and fossil sources

New processes under development for producing hydrogen have been assessed using a life cycle methodology and compared to conventional ones. The aim of this paper is to determine the main obstacles to be beaten or the critical aspects to be addressed to ensure the feasibility of these processes. Water photosplitting, solar two-step thermochemical cycles and automaintained methane decomposition with different lay-outs were studied. They have been compared to methane steam reforming with CCS and electrolysis with different electricity sources.     

Integrated fossil fuel and solar thermal systems for hydrogen production and CO2 mitigation

In most current fossil-based hydrogen production methods, the thermal energy required by the endothermic processes of hydrogen production cycles is supplied by the combustion of a portion of the same fossil fuel feedstock. This increases the fossil fuel consumption and greenhouse gas emissions. This paper analyzes the thermodynamics of several typical fossil fuel-based hydrogen production methods such as steam methane reforming, coal gasification, methane dissociation, and off-gas reforming, to quantify the potential savings of fossil fuels and CO₂ emissions associated with the thermal energy requirement. Then matching the heat quality and quantity by solar thermal energy for different processes is examined. It is concluded that steam generation and superheating by solar energy for the supply of gaseous reactants to the hydrogen production cycles is particularly attractive due to the engineering maturity and simplicity. It is also concluded that steam-methane reforming may have fewer engineering challenges because of its single-phase reaction, if the endothermic reaction enthalpy of syngas production step (CO and H₂) of coal gasification and steam methane reforming is provided by solar thermal energy. Various solar thermal energy based reactors are discussed for different types of production cycles as well.     

Potential of renewable hydrogen production for energy supply in Hong Kong

Hong Kong is highly vulnerable to energy and economic security due to the heavy dependence on imported fossil fuels. The combustion of fossil fuels also causes serious environmental pollution. Therefore, it is important to explore the opportunities for clean renewable energy for long-term energy supply. Hong Kong has the potential to develop clean renewable hydrogen energy to improve the environmental performance. This paper reviews the recent development of hydrogen production technologies, followed by an overview of the renewable energy sources and a discussion about potential applications for renewable hydrogen production in Hong Kong. The results show that although renewable energy resources cannot entirely satisfy the energy demand in Hong Kong, solar energy, wind power, and biomass are available renewable sources for significant hydrogen production. A system consisting of wind turbines and photovoltaic (PV) panels coupled with electrolyzers is a promising design to produce hydrogen. Biomass, especially organic waste, offers an economical, environmental-friendly way for renewable hydrogen production. The achievable hydrogen energy output would be as much as 40% of the total energy consumption in transportation.     

An assessment of the impacts of renewable and conventional electricity supply on the cost and value of power-to-gas

Power-to-gas (P2G) is a promising enabling technology for more cross-sector integration but its high cost has so far been a key barrier to implementation. Electricity supply is the greatest contributor to the levelised cost therefore it is important to understand which technologies and strategies can minimise the cost and accelerate the deployment. In this study, a method is devised to evaluate the cost and value of combined systems comprising P2G and renewable energy technologies such as solar photovoltaics, wind and hydro as well as comparing to traditional electricity supply via the wholesale market. The proposed models are based on a temporal resolution of 1 h and include partial operation and ageing throughout the system's lifespan. Our analysis covers both distributed and centralised P2G systems producing hydrogen or methane as well as various value-adding services across different geographies. It is found that the capacity factor of a P2G system drives the economic case and therefore the electricity supply from hydropower plants is economically more attractive than electricity from wind and solar photovoltaic plants in this order. Under today's market conditions, it is highly advisable to combine local renewable supply with wholesale-based supply but interestingly, a 20% capital cost reduction in wind technology or a P2G system efficiency of 80% are break-even points for P2G systems producing hydrogen and connected to wind plants.     

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.     

Comparative life cycle assessment of hydrogen pathways from fossil sources in China

Emissions of multiple hydrogen production pathways from fossil sources were evaluated and compared with that of fossil fuel production pathways in China by using the life cycle assessment method. The considered hydrogen pathways are gasoline reforming, diesel reforming, natural gas reforming, soybean‐derived biodiesel (s‐biodiesel) reforming, and waste cooking oil‐derived biodiesel reforming. Moreover, emissions and energy consumption of fuel cell vehicles utilizing hydrogen from different fossil sources were presented and compared with those of the electric vehicle, the internal combustion engine vehicle, and the compression ignition engine vehicle. The results indicate both fuel cell vehicles and the electric vehicle have less greenhouse gas emissions and energy consumption compared with the traditional vehicle technologies in China. Based on an overall performance comparison of five different fuel cell vehicles and the electric vehicle in China, fuel cell vehicles operating on hydrogen produced from natural gas and waste cooking oil‐derived biodiesel show the best performance, whereas the electric vehicle has the worse performance than all the fuel cell vehicles because of very high share of coal in the electricity mix of China. The emissions of electric vehicle in China will be in the same level with that of natural gas fuel cell vehicle if the share of coal decreases to around 40% and the share of renewable energy increases to around 20% in the electricity mix of China. Copyright © 2016 John Wiley & Sons, Ltd.