Authors have proposed a new hydrogen production system that simultaneously synthesizes hydrogen and hydrogen peroxide from water by electrochemical reaction. Experimental apparatus of this system is composed of a hydrogen electrode with platinum mesh, a hydrogen peroxide electrode with carbon material and an electrolyte with Nafion®. In this paper, the superiority of this system is outlined. In addition, the experimental results of electrolytic synthesis of hydrogen and hydrogen peroxide from water are reported. Furthermore, the possibility of the system that synthesizes hydrogen and hydrogen peroxide from water by the photochemical reaction using solar radiation is also discussed.

The photocatalytic splitting of water into hydrogen and oxygen using solar energy is one of the most attractive renewable sources of hydrogen fuel. Therefore, considerable efforts have been paid in developing photocatalysts capable of using visible light, which accounts for about 43% of the solar energy. However such a photocatalyst has not been developed so far. We have developed a new Ni-doped indium-tantalum oxide photocatalyst, In 1-x Ni x TaO 4 (x = 0.0∼0.2), which induced direct splitting of water into stoichiometric amount of oxygen and hydrogen under visible light irradiation with a quantum yield of about 0.66% at 420.7 nm. We have also developed a new two-step water splitting system using two different semiconductor photocatalysts, Pt/WO 3 photocatalyst for oxygen evolution and Pt/SrTiO 3 (Cr-Ta-doped) photocatalyst for hydrogen evolution, and a redox mediator, I − /IO 3 − , mimicking the Z-scheme mechanism of the natural photosynthesis. The quantum yield of this system was about 0.1% at 420.7nm. Both photocatalytic methods are the first examples for visible light water splitting system in the world.

Two renewable approaches to advanced solar supported hydrogen generation are presented. For the near and midterm, Hydrogen from solar reforming might be a viable, and economic approach. For the long-term, hydrogen generated by solar supported electrolysis of water will hold great promise for clean hydrogen production.

This paper presents the development of photoelectrochemical (PEC) setup using multiple bandgap combination of CuIn 1−x Ga x S 2 (CIGS 2 ) thin-film photovoltaic (PV) cell and ruthenium oxide (RuO 2 ) photocatalyst. FSEC PV Materials Lab has developed a PEC setup consisting of two illuminated CIGS 2 cells, a ruthenium oxide (RuO 2 ) anode deposited on titanium sheet for oxygen evolution and a platinum foil cathode for hydrogen evolution. With this combination, a PEC efficiency of 4.29% has been achieved.

An innovative heat storage system with metal hydride (MH) applied to air conditioning of buildings is investigated. The characteristics that metal hydride generates heat at absorption process and absorbs heat at desorption process is useful for new air conditioning system without chlorofluorocarbon (CFC). The trial system is composed of two heat storage vessels of a “shell and tube type” heat exchanger with heat transfer fins and filled with MH and a compressor equipped for hydrogen transfer. The system proposed in this paper is simple because the heat storage vessel has two functions of heat source and heat storage, and suitable for environment because of no usage of CFC. The purpose of heat storage is to decrease the difference of the electric power demand at daytime and that at night. That is to say, the effective heat storage system consumes electric power at night and requires no power at daytime. In the innovative heat storage system with metal hydride, the hydrogen is transferred using electric power at night and transferred in reverse only by the pressure difference between two heat storage vessels at daytime. The trial system was operated at actual loading condition, and the performance of the MH heat storage system was evaluated. As the experimental result, heat storage finishes in a limited time, and heat quantity for cooling was 13.5MJ, which was sufficient for the heat capacity to cool the 10m 2 room for 3 hours. In addition, the coefficient of performance of the system is 2.44.

Hydrogen is a clean and sustainable form of carrier of energy that can be used in mobile and stationary applications. At present hydrogen is produced mostly from fossil sources. Solar photoelectrochemical processes are being developed for hydrogen production. Storing hydrogen can be done in three main ways: in compressed form, liquid form and by chemical bonding. Near term spaceport operations are one of the prominent applications for usage of large quantities of liquid hydrogen as a cryogenic propellant. Efficient storage and transfer of liquid hydrogen is essential for reducing the launch costs. A Two Stage Reverse Turbo Brayton Cycle (RTBC) CryoCooler is being developed at University of Central Florida. The cryocooler will be used for storage and transport of hydrogen in spaceport and space vehicle application. The efficiency of the compressor and motor of the cryocooler depends mainly on the friction and wear between the mating parts. Tribological coatings having extremely high hardness, ultra-low coefficient of friction, and high durability at temperatures lower than 60 K are being developed with an aim to reduce the friction and wear, thereby resulting in improved efficiency of the cryocooler. Extremely hard and extremely low friction coatings of DLC, TiN coatings and DLC/MoS 2 and TiN/MoS 2 bilayer coatings have been chosen as part of this ongoing research aimed for this application. This paper presents preparation; characterization (SEM and XRD), microhardness and tribological measurements carried out on TiN and TiN/MoS 2 coatings on aluminum and glass substrate.

Today’s production of renewable hydrogen using energy sources such as solar and wind is too expensive compared with conventional production, normally by an order of magnitude. The high costs are a major bottleneck for the launch of the hydrogen economy. This paper will present a bypass of this bottleneck, which is a compromise between the use of fossil and solar energy: the solar steam reforming of natural gas (NG). It comprises the production of hydrogen from NG and the use of solar energy as the renewable source at low cost. Using the solar reformer technology for generation of hydrogen, we expect fuel savings of up to 40% compared to a conventional plant. Therefore, the CO 2 emissions can be reduced accordingly. Based on the experiences in DLR solar reformers, which were successfully demonstrated at a level of few hundred kW in previous EC co-funded projects (e.g. SOLASYS), industrial plant layouts were developed. For a 50 MW th solar reforming plant a cost study was prepared. Two process layouts were investigated and the hydrogen costs were calculated. Sensitivity analyses of different parameters such as the natural gas prize were conducted. The conceptual layout of a solar driven hydrogen production plant comprises the innovative solar reformer followed by a water gas shift reactor and gas separation units. For the separation of hydrogen and carbon dioxide a PSA unit and gas washing unit using methyldiethanolamine (MDEA) are considered. The remaining methane rich gas is recycled to the process. The results of this cost study show that hydrogen produced by solar reforming costs between 4.5 and 4.7ct € / kWh (LHV of H 2 ). Therefore it is only about 20% more expensive than conventionally produced hydrogen. Increasing the cost of methane (NG) will result in favorable conditions for the solar hydrogen.

Hydrogen production from solar-driven thermochemical water splitting cycles (TCWSCs) provides an approach that is energy efficient and environmentally attractive. Of particular interest are TCWSCs that utilize both thermal ( i.e. high temperature) and light ( i.e. quantum) components of the solar resource, boosting the overall solar-to-hydrogen conversion efficiency compared to those with heat-only energy input. We have analyzed two solar-driven TCWSCs: 1) carbon dioxide (CO 2 )/carbon monoxide cycle; and 2) sulfur dioxide (SO 2 )/sulfuric acid cycle. The first cycle is based on the premise that CO 2 becomes susceptible to near-ultraviolet and even visible radiation at high temperatures (greater than 1300K). The second cycle is a modification of the well-known Westinghouse hybrid cycle, wherein the electrochemical step is replaced by a photocatalytic step. At the Florida Solar Energy Center (FSEC), a novel hybrid photo-thermochemical sulfur-ammonia (S-A) cycle has been developed. The main reaction (unique to FSEC’s S-A cycle) is the light-induced photocatalytic production of hydrogen and ammonium sulfate from an aqueous ammonium sulfite solution. Ammonium sulfate product is processed to generate oxygen and recover ammonia and SO 2 that are then recycled and reacted with water to regenerate the ammonium sulfite. Experimental data for verification of the concept are provided.

Solar power towers can be used to make hydrogen on a large scale. Electrolyzers could be used to convert solar electricity produced by the power tower to hydrogen, but this process is relatively inefficient. Rather, efficiency can be much improved if solar heat is directly converted to hydrogen via a thermochemical process. In the research summarized here, the marriage of a high-temperature (∼1000 °C) power tower with a sulfuric acid/hybrid thermochemical cycle (SAHT) was studied. The concept combines a solar power tower, a solid-particle receiver, a particle thermal energy storage system, and a hybrid-sulfuric-acid cycle. The cycle is “hybrid” because it produces hydrogen with a combination of thermal input and an electrolyzer. This solar thermochemical plant is predicted to produce hydrogen at a much lower cost than a solar-electrolyzer plant of similar size. To date, only small lab-scale tests have been conducted to demonstrate the feasibility of a few of the subsystems and a key immediate issue is demonstration of flow stability within the solid-particle receiver. The paper describes the systems analysis that led to the favorable economic conclusions and discusses the future development path.

Near-term and cost-effective production of solar hydrogen from inexpensive and readily available hydrogen containing compounds (HCCs) can boost the prospects of future hydrogen economy. In this paper, we assess the prospects of solar-assisted conversion of HCCs into hydrogen using polyoxometalate (POM) based photocatalysts, such as isopolytunstates (IPT) and silicotungstic acid (STA). Upon exposure to solar photons, IPT aqueous solutions containing various HCCs ( e.g. alcohols, alkanes, organic acids, sugars, etc.) produce hydrogen gas and corresponding oxygenated compounds. The presence of small amounts of colloidal platinum increases the rate of hydrogen evolution by one order of magnitude. A solar photocatalytic flat-bed reactor, approximately 1.2 m × 1.2 m in size, was fabricated and tested for production of hydrogen from water-alcohol solutions containing IPT and STA and small amounts of colloidal Pt. The solar photoreactor tests demonstrated steady-state production of hydrogen gas for several days. IPT immobilized on granules of anion exchange resins with quaternary ammonium active groups show good photocatalytic activity for hydrogen production from water-alcohol solutions exposed to near-UV or solar radiation.

As a new clean energy source and important material, the use and demand of hydrogen are increasing-rapidly. So that bio-hydrogen producing technology moves toward cutting down the operation costs in recent years. Biohydrogen production capacity improvement and cost reduction are two key points for industrialization of the process. Biohydrogen production has been studied in China for over 20 years in both photosynthetic hydrogen production and fermentative processes fields. The anaerobic process of fermentative hydrogen production has been developing in China since 1990s. The isolation and identification of high efficient bio-hydrogen production anaerobic bacteria is an important foundation of fermentative bio-hydrogen production process by anaerobic digestion of organic wastewater. The paper focuses on: (1) Fermentative biohydrogen production system, (2) Laboratory experiments and pilot scale tests for continued hydrogen production, (3) Fermentation types and their engineering control, (4) isolation, culture media and characterization of anaerobes, (5) Applications of pure bacteria, (6) Fundamental researches including ecology, genetics and improvements, (7) Development of two-phase anaerobic process of H2-producing and methanogenic phases as, and (8) the integrated processes with bioengineering and wastewater treatments. Recently, the first pilot factory has been costructedin Harbin, China by hydrogen production rate of more than 1200m3/d which located in northeast of China. In photosynthetic hydrogen production filed, study is focused on the fundamentals, engineering application and microbiology. Detailed discussion comes later.

There are not many non-biological resources that can be extracted from the ocean without causing serious environmental impact and whose extraction is concomitantly sustainable. But among the few ones it is appropriate to mention ocean energy. The exploitation of these has been suggested for centuries, often decried, only exceptionally undertaken. It is perhaps opportune to reconsider them because, mega-projects set aside, they could bring an appreciable relief to the heavy burden that weighs upon isolated areas, poor countries, deprived of hydrocarbon reserves, for their energy needs.

Nine research groups from four countries have been collaborating for 4.5 years under Annex-14 with the aim to advance the science underlying photoelectrolytic hydrogen production from water-splitting. Significant research progress has been made in the areas of material science (semiconductor photoelectrodes, light absorption, photocatalyst stability and charge transfer) and systems development (monolithic multijunction systems, two-photon tandem systems, dual-bed redox systems and monomaterial two-step systems), resulting in the synthesis as well as development of new photoactive materials and the demonstration of various photoelectrochemical (PEC) water-splitting prototype devices, limited to typical laboratory-size miniature scales.

A very promising method for the conversion and storage of solar energy into a fuel is the dissociation of water to oxygen and hydrogen, carried out via a two-step process using metal oxide redox systems such as mixed iron oxides, coated upon multi-channeled honeycomb ceramic supports capable of absorbing solar irradiation, in a configuration similar to that encountered in automobile exhaust catalytic converters. With this configuration, the whole process can be carried out in a single solar energy converter, the process temperature can be significantly lowered compared to other thermo-chemical cycles and the re-combination of oxygen and hydrogen is prevented by fixing the oxygen in the metal oxide. For the realization of the integrated concept, research work proceeded in three parallel directions: synthesis of active redox systems, manufacture of ceramic honeycomb supports and manufacture, testing and optimization of operating conditions of a thermochemical solar receiver-reactor. The receiver-reactor has been developed and installed in the solar furnace in Cologne, Germany. It was proven that solar hydrogen production is feasible by this process demonstrating that multi cycling of the process was possible in principle.

The counter-rotating-ring receiver/reactor/recuperator (CR5) solar thermochemical heat engine is a new concept for production of hydrogen that allows for thermal recuperation between solids in an efficient counter-current arrangement. At the heart of the CR5 system are annular rings of a reactive solid ferrite that are thermally and chemically cycled to produce oxygen and hydrogen from water in separate and isolated steps. This design is very demanding from a materials point of view. The ferrite rings must maintain structural integrity and high reactivity after months of thermal cycling and exposure to temperatures in excess of 1100 °C. In addition, the design of the rings must have high geometric surface area for gas-solid contact and for adsorption of incident solar radiation. After performing a series of initial screenings, we chose Co 0.67 Fe 2.33 O 4 as our baseline working material for a planned demonstration of CR5 and have begun additional characterization and development of this material. Our results to date with powders are consistent with the expectation that small particle sizes and the application of a support to inhibit ferrite sintering and enhance the chemistry are critical considerations for a practical operating device. Concurrent with the powder studies, we are using Robocasting, a Sandia-developed technique for free form processing of ceramics, to manufacture monolithic structures with complex three-dimensional geometries for chemical, physical, and mechanical evaluation. We have demonstrated that ferrite/zirconia mixtures can be fabricated into small three-dimensional monolithic lattice structures that give reproducible hydrogen yields over multiple cycles.

Hydrogen is an energy vector of considerable recent interest because of its perceived environmental benignity. Aspects of the hydrogen economy are addressed in this article by quantifying associated impacts and costs. For the first time, important questions are addressed in a comprehensive way. Impact assessments and external cost analyses investigate whether hydrogen should replace standard fuels and which production technologies are preferred. Finally, the life cycle stages of that contribute the largest impacts are identified. If external costs are to be minimized in the operation of a U.S. hydrogen economy, it is recommended that hydrogen (H 2 ) be produced from solar thermochemical (STC) cycles and wind electrolysis, with the possible use of steam methane reforming (SMR). The external costs associated with biomass gasification are shown to be comparable with those for wind electrolysis. Thus, biomass-produced hydrogen could also be a viable alternative, especially in areas ideally suited to the growth of energy crops. Finally, the most influential life cycle stages are the Construction of the Fuel Cell Vehicle (FCV) and Hydrogen Production (except for the environmentally benign wind electrolysis). For the wind/electrolysis case, the majority of impacts come from plant construction.

A possible future approach to home and personal vehicle energy needs is to combine solar power generation on the structure with hydrogen production and use. In this paper, performance of a solar-hydrogen system for residential application is simulated. Included in the main components of the solar-hydrogen system are photovoltaic panels, electrolyzer, fuel cell, compressor, and storage tank. The solar-hydrogen system is assumed to be installed on the standard house (1600 sq ft), to be a part of a grid-connected system where the house can receive energy from both grid as well as PV panels and fuel cell based on the energy requirements of the house. Using yearly weather data for Las Vegas, net grid interaction as well as stand alone (off grid) performance is considered as part of the analysis. The effect of component sizing aspects is examined.

This paper describes the design of a 14 kW grid-tied photovoltaic system for powering a hydrogen generation and refueling station that is being constructed at the Las Vegas Valley Water District. The fixed array layout is determined by considering the available space, aesthetics and impact of shading on annual energy production. Computer simulations using PV-DesignPro software and area hourly solar radiation data are conducted to simulate the energy flow into and out of the electric utility grid for different profiles of hydrogen use. Stand-alone system operation is also simulated to estimate the maximum amount of hydrogen that can be produced under limited storage.

Production of hydrogen using solar thermal energy has the potential to be a viable alternative to other hydrogen production methods, typically fossil-fuel driven processes. Thermochemical reactions for splitting water require high temperatures to operate effectively, for which solar is well-suited. Numerical modeling to investigate the concept of a solar-driven reactor for splitting water is presented in detail in this paper for an innovative reactor, known as the “counter-rotating-ring receiver/reactor/recuperator” (CR5) solar thermochemical heat engine that is presently under development. In this paper, details of numerical simulations predicting the thermal/fluid behavior of the innovative solar-driven thermo-chemical reactor are described in detail. These scoping calculations have been used to provide insight into the thermal behavior of the counter-rotating reactor rings and to assess the degree of flow control required for the CR5 concept.

A major effort to develop a renewably-based hydrogen generation/utilization system is described. This system consists of PV-powered electrolysis and compression units and hydrogen-fueled vehicles. Both conventional and high-pressure PEM electrolysis units are included. On the utilization side, both fuel cell and ICE powered vehicles are being developed. Each of these aspects is described in the paper.