Solar Hydrogen Energy Systems: Science and Technology for the Hydrogen Economy

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Despite the advantages, hydrogen fuel technology still faces challenges. For instance, the electrodes used in water electrolysis are currently coated with platinum, which is not a sustainable resource, and researchers are currently investigating other materials. Other issues include transporting hydrogen - a recent study has shown that it is more economical to deliver hydrogen by truck to refueling stations rather than perform on-site electrolysis.

Another hurdle is storage - in terms of sustainability, Abbott suggests that the most straightforward approach is to liquefy the hydrogen. Although liquefying hydrogen requires an additional energy cost, Abbott argues that the scenario should not be mistaken for a zero-sum game as is the case with fossil fuels. Since the sun supplies a virtually unlimited amount of energy, the solution is to factor in the non-recurring cost of extra solar collectors to provide the energy for liquefaction.

His calculations show that the cost of a solar collector farm used to produce hydrogen is still lower than a nuclear station of equivalent power. Overall, Abbott's message is that there exists a single technology that can supply the world's energy needs in a clean, sustainable way: The difference in his approach compared to other analyses, he explains, is his long-term perspective.

While nuclear power is often cited to be the economically favorable technology in the short-term, Abbott argues that the long-term return on nuclear power is virtually zero due to its limited lifetime, while solar-hydrogen power can theoretically last us the next one billion years. Of course, Abbott's analysis is just one approach in the ongoing debate on the advantages and disadvantages of hydrogen.

Among several reviews published in a special issue of the Proceedings of the IEEE in October is an analysis by Ulf Bossel, which shows that a hydrogen economy is uncompetitive due to the energy costs of storage, transportation, etc. Abbott agrees that hydrogen is not an efficient energy storage method, but he also points out that energy from the sun is virtually unlimited, and more solar collectors could make up for the inefficiency of hydrogen technology. There is so much solar that all you have to do is invest in the non-recurring cost of more dishes to drive a solar-hydrogen economy at whatever efficiency it happens to sit at.

So let's begin now, what are we waiting for? How do we supply the world's energy needs?

Why a hydrogen economy doesn't make sense. In a recent study, fuel cell expert Ulf Bossel explains that a hydrogen economy is a wasteful economy. The large amount of energy required to isolate hydrogen from natural compounds water, natural gas, biomass , package A small CSIRO-developed hydrogen device the size of a domestic microwave oven may be all you need to fuel your car in the future.

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What does the future hold for solar power? The Hydrogen production was accomplished at When a bird in flight lands, it performs a rapid pitch-up maneuver during the perching process to keep from overshooting the branch or telephone wire. In aerodynamics, that action produces a complex phenomenon known as dynamic Conventional lithium ion batteries, such as those widely used in smartphones and notebooks, have reached performance limits.

MIT researchers have 3-D printed a novel microfluidic device that simulates cancer treatments on biopsied tumor tissue, so clinicians can better examine how individual patients will respond to different therapeutics—before Google said Monday it will close the consumer version of its online social network sooner than originally planned due to the discovery of a new software bug.

A Chinese court ordered a ban in the country on iPhone sales in a patent dispute, US chipmaking giant Qualcomm said Monday. Ride-share company Uber quietly filed paperwork this week for its initial public offering, the Wall Street Journal reported late Friday. Please sign in to add a comment. Registration is free, and takes less than a minute. Why a hydrogen economy doesn't make sense December 11, In a recent study, fuel cell expert Ulf Bossel explains that a hydrogen economy is a wasteful economy.

Understanding dynamic stall at high speeds December 18, When a bird in flight lands, it performs a rapid pitch-up maneuver during the perching process to keep from overshooting the branch or telephone wire. Adjust slider to filter visible comments by rank. Simply declaring something false does not make it so. Please provide credible references to back that allegation up. That the oil in Montana area alone is in the trillions of barrels.. I personally do not believe we need to be using oil and want to get rid of it except for industrial purposes and in areas whee it is indispensable.

We don't need to be polluting with it. However, I will not put up with the direct lie about scarcity--utilized as a control device, as a lever on the people. What a lame hackjob. The average crustal abundance of uranium and thorium corresponds to barrels of oil per tonne when effectively used. Any old junk contains far more energy that can be unlocked with nuclear fission than the most concentrated coal mines, gas or oil wells. Instead of the government strong-arming the nuclear industry to treat it as waste and burrying it, it should be treated as the valuable resource it is and it should be used as starter charges for breeder reactors I happen to like liquid fluoride thorium reactors a lot more than fast reactors, but this is a minor point in the big scheme of things.

The discrepancy comes from a hidden assumption. This is pure idiocy even if you are considering only light water reactors since it corresponds to the highest acceptable cost being a fraction of a cent per kWh. Nuclear fission is sustainable for the next billion years. Critics like to rant about the high government imposed costs of nuclear power; they nearly never talk about the costs of solar power. Solar will be feasible cost competitive some day, but it is not now. Even when it is, the energy intensity of gasoline and diesel will outpace electricity for many uses.

The projections for fossil fuels supply are very low. Nuclear fuels have about 30, years supply. Hydrogen remains very hard to store for any length of time because of extreme pressure and cold requirements. Producing hydrogen from electricity is extremely inefficient, about 9 units of power for each unit power of hydrogen available. The answer is continued technology development, and less time spent on speculation.

How a Solar-Hydrogen Economy Could Supply the World's Energy Needs

It goes on to say the buoyancy of the hydrogen keeps it from igniting at the tank itself, keeping it from superheating the tank and leading to a catastrophic explosion. My real reason for replying is lubrication. The man they are quoting says a limiting factor of wind turbines is lubricating the turbines, a mere 20 gallons ever 5 years per turbine, but makes no statements regarding the lubrication of Sterling and Rankine engines.

This seems like a purposeful omission on his part to give more credibility to his solar power stance since a similar amount of lubrication would be needed to power said engines, leading to his 'lubrication crisis' in a few decades. LariAnn, pro-fission people don't bother with facts. Otherwise how could they face themselves in the morning? Physorg mutilates my euro sign. If the cost over-run for a first of a kind reactor is a few billion euros the antis get their panties in a knot. Yet the same 'tards advocate power plants that are at least an order of magnitude more expensive still.

The Solar constant is Watts per square meter A typical non-tracking PV-installation optimizes for the worst case i. Efficiency declines with age over it's year lifespan. Velanarris; yes there are some cranks that think thermite was an important aspect of Hindenburg; they are wrong. There was much too little aluminium and iron oxide in the paint and it was separated, not uniformly mixed.

Thermite has never been a component of explosives or rocket fuel; the military used the stuff in incendiary devices to set fire to stuff and it has been extensively used for welding rail-roads. Mythbusters tried the same recipe used in hindenburg's cloth and it didn't do dick as an accelerant. Yes, some cranks still believe that and you can find some by scraping geocities. But whenever someone actually tests it e. Molecular Hydrogen is unnatural and energy inefficient. Hydrogen technology naturally leaks which rises to the upper atmosphere and depletes the ozone layer and forms water in the high atmosphere which is normally dry.

Water is a vastly more potent greenhouse gas than CO2 and may be far worse than the CO2 released by fossil fuels currently used. Bio diesel is carbon neutral and much less flammable than either gas or hydrogen. Bio diesel can be integrated with current infrastructure without massive investments of money and energy. Clean diesel cars are now available that get 70 mpg without added expense and hazardous waste of hybrids.

The best answers will always be lost to political expediency and ideologist fervor. A discussion on energy seems as good a place as any to pose this question. In the space shuttle Columbia performed a test with a tethered satelite to look into harvesting energy. Unfortunately the tether broke and the experiment was incomplete. At the time I remember hearing that the tether broke because a bolt of the electricity being gathered struck it at the point where it connected to the boom, and also that it had generated huge amounts of electricity something about enough to run New York City.

Unfortunately I'm having trouble finding any data to support this, so if anyone can give me a source I would appreciate it. What I do know is that in the process of developing ground tethered space stations someone gave me the term Skyhook, which sounded good to me, guess it's from StarWars or something they have to deal with this, or a similar effect.

Unfortunately when I tried to get answers from several individuals who are working on the project at Washington State University I never got responses back, as though they're busy or something. The questions, after all that, are these: Could that electricity be harnessed? How much would it be? If it could be harnessed it would seem like it would be quite the renewable energy source.

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I am all for creating a new energy system and analysis like this provide a great basis for discussion. The one hole I keep seeing in these arguments is there never seems to be an analysis of the effect of all this water vapor being released into the atmosphere. Hydrogen is considered a 'Clean' technology, but I have not seen a credible analysis of what will happen when the water vapor from every vehicle on the planet is being released into the air.

Will it increase cloud cover? Will we have global cooling due to the increase in cloud cover? Are there other environmental impacts we should consider? What happens to all this solar power generation when there is less sunlight getting through? I don't claim to know the answers to these questions, but they are similar to the questions we should have asked before destroying our environment with emissions from numerous other energy sources. A Solar-Hydrogen energy combo may be the best solution we have, but we really need to stop calling it a perfectly 'Clean' energy solution.

Let look at ALL the tradeoffs before over committing ourselves in any one direction. Bio diesel is carbon neutral If carbon has a year half life in the atmosphere, as is suggested by the AGW hypothesists then you cannot state that biodiesel is carbon neutral as you cannot quantify that ALL carbon released was taken up through respiration, which it was not. There's a lot of misunderstanding in the plant carbon cycle. Plants create hydrocarbons utilizing CO2, water, and energy sunlight. The plant then burns those hydrocarbons at night and releases CO2. If that was the case it would not be usable in diesel engines which use a lower heat than gasoline engines.

A bio-reactor tank of algae can have it's inputs and outputs precisely measured so there is no guesswork as to where the carbon comes from. New solid catalyst reactors plants are in the works that are designed for up to 50 million gallons of fuel production per year. The flammability of diesel does not correspond to it's energy content. Diesel actually has greater density of energy than gasoline, but has a low vapor pressure so it does not ignite if you throw a match into a bucket of it.

Plants don't use the same amount of carbs at night as they synthesis during daylight. If they did they would not get bigger over time. All the CO2 that biofuels release come from the air. If the land used to grow them was wasteland e. One carbon in net after night time release minus one carbon out equals neutral. TrinityComplex the reason why it isn't workable is because its the equivalent of a generator - only using the earth instead of a traditional magnet and the coils docked to the ship as the motor coils.

To make a generator work you have to add energy and the motion of the ship against the earth's magnetic field is where the power comes from. As electricity is flowing in the coil it creates a counter magnetic force to the earths magnetic field and in effect would slow the ship down thats why the cable experienced forces that snapped it because they didn't anticipate it dragging against the ship so aggressively. Really the test was an engineering failure that with more study would have been scrapped before launch since you would need to continuously boost the ship to maintain orbit as the coil dragged you back.

I used to wonder what happened to that experiment too. As for ground tethered i think if it was stationary there would be no net magnet force from the earth since it moves along with the planet's movement. Buses in Munich have been running on hydrogen gas since I haven't heard of any explosions?

And they run on time! We love to deflect from real problems, which are defective human instincts for this niche, and too many humans, an emergent effect from the sexual instinct. But we can't even THINK about population reduction, the easiest way to carbon reduction don't burn the bodies! This has all been said before. There is an effort to promote the Hydrogen Economy call the Pheonix Project.

You can be a genius and have all these fantastic ideas to help the world but if you don't have the power, it does not do any good. The one that wield the power decide the courses of the world. I am not one of them and I wield no power. But it does not means I do not acknowledge reality. As one of the law of reality is: Either you acknowledge reality or it will work against you.

And one of the reality is Might makes right. Although I find this report interesting, it does not tell me anything that the Pheonix Project by Harry Braun did not tell me. They are becoming cheaper and cheaper sources of energy. I have invented a way to get greater than double the amount of electricity from solar power towers and other concentrating solar collectors such as sun catchers, and parabolic troughs.

I can give you a lot of details on my solar system at protn7 att. Someone should fire the professor!! While I really like CSP solar, it's best use is in home size units and it supplies hot water, heat too. And you can store the heat or run it from any fuel too if the sun don't shine and you need the power. Biological hydrogen can be produced in bioreactors that use feedstocks other than algae, the most common feedstock being waste streams.

The process involves bacteria feeding on hydrocarbons and excreting hydrogen and CO 2. The CO 2 can be sequestered successfully by several methods, leaving hydrogen gas. In , NanoLogix first demonstrated a prototype hydrogen bioreactor using waste as a feedstock at Welch's grape juice factory in North East, Pennsylvania U. Besides regular electrolysis, electrolysis using microbes is another possibility. With biocatalysed electrolysis, hydrogen is generated after running through the microbial fuel cell and a variety of aquatic plants can be used.

These include reed sweetgrass , cordgrass, rice, tomatoes, lupines, and algae [45]. High pressure electrolysis is the electrolysis of water by decomposition of water H 2 O into oxygen O 2 and hydrogen gas H 2 by means of an electric current being passed through the water. The difference with a standard electrolyzer is the compressed hydrogen output around bar psi , 12—20 MPa.

How a Solar-Hydrogen Economy Could Supply the World's Energy Needs

Hydrogen can be generated from energy supplied in the form of heat and electricity through high-temperature electrolysis HTE. Because some of the energy in HTE is supplied in the form of heat, less of the energy must be converted twice from heat to electricity, and then to chemical form , and so potentially far less energy is required per kilogram of hydrogen produced.

While nuclear-generated electricity could be used for electrolysis, nuclear heat can be directly applied to split hydrogen from water. Research into high-temperature nuclear reactors may eventually lead to a hydrogen supply that is cost-competitive with natural gas steam reforming. In addition, this is lower-quality "commercial" grade Hydrogen, unsuitable for use in fuel cells. Using electricity produced by photovoltaic systems offers the cleanest way to produce hydrogen. Water is broken into hydrogen and oxygen by electrolysis—a photoelectrochemical cell PEC process which is also named artificial photosynthesis.

Hydrogen evolved on the front amorphous silicon surface decorated with various catalysts while oxygen evolved off the back metal substrate. A Nafion membrane above the multijunction cell provided a path for ion transport. Their patent also lists a variety of other semiconductor multijunction materials for the direct water splitting in addition to amorphous silicon and silicon germanium alloys. Research continues towards developing high-efficiency multi-junction cell technology at universities and the photovoltaic industry. If this process is assisted by photocatalysts suspended directly in water instead of using photovoltaic and an electrolytic system, the reaction is in just one step, which can improve efficiency.

A method studied by Thomas Nann and his team at the University of East Anglia consists of a gold electrode covered in layers of indium phosphide InP nanoparticles. In , it was reported that Panasonic Corp. Very high temperatures are required to dissociate water into hydrogen and oxygen. A catalyst is required to make the process operate at feasible temperatures. Heating the water can be achieved through the use of concentrating solar power. Hydrosol II has been in operation since The design of this kilowatt pilot plant is based on a modular concept. As a result, it may be possible that this technology could be readily scaled up to the megawatt range by multiplying the available reactor units and by connecting the plant to heliostat fields fields of sun-tracking mirrors of a suitable size.

There are more than [58] thermochemical cycles which can be used for water splitting , [59] around a dozen of these cycles such as the iron oxide cycle , cerium IV oxide-cerium III oxide cycle , zinc zinc-oxide cycle , sulfur-iodine cycle , copper-chlorine cycle and hybrid sulfur cycle are under research and in testing phase to produce hydrogen and oxygen from water and heat without using electricity. Thermochemical production of hydrogen using chemical energy from coal or natural gas is generally not considered, because the direct chemical path is more efficient.

None of the thermochemical hydrogen production processes have been demonstrated at production levels, although several have been demonstrated in laboratories. The industrial production of chlorine and caustic soda by electrolysis generates a sizable amount of Hydrogen as a byproduct. In the port of Antwerp a 1MW demonstration fuel cell power plant is powered by such byproduct. This unit has been operational since late Although molecular hydrogen has very high energy density on a mass basis, partly because of its low molecular weight , as a gas at ambient conditions it has very low energy density by volume.

If it is to be used as fuel stored on board the vehicle, pure hydrogen gas must be stored in an energy-dense form to provide sufficient driving range. Increasing gas pressure improves the energy density by volume, making for smaller, but not lighter container tanks see pressure vessel. Achieving higher pressures necessitates greater use of external energy to power the compression. The mass of the hydrogen tanks needed for compressed hydrogen reduces the fuel economy of the vehicle. Because it is a small molecule, hydrogen tends to diffuse through any liner material intended to contain it, leading to the embrittlement , or weakening, of its container.

Alternatively, higher volumetric energy density liquid hydrogen or slush hydrogen may be used. However, liquid hydrogen is cryogenic and boils at Cryogenic storage cuts weight but requires large liquification energies. The liquefaction process, involving pressurizing and cooling steps, is energy intensive. Liquid hydrogen storage tanks must also be well insulated to minimize boil off. Japan have a liquid hydrogen LH2 storage facility at a terminal in Kobe, and are expected to receive the first shipment of liquid hydrogen via LH2 carrier in A potential efficiency loss of Distinct from storing molecular hydrogen, hydrogen can be stored as a chemical hydride or in some other hydrogen-containing compound.

Hydrogen gas is reacted with some other materials to produce the hydrogen storage material, which can be transported relatively easily. At the point of use the hydrogen storage material can be made to decompose, yielding hydrogen gas. As well as the mass and volume density problems associated with molecular hydrogen storage, current barriers to practical storage schemes stem from the high pressure and temperature conditions needed for hydride formation and hydrogen release. For many potential systems hydriding and dehydriding kinetics and heat management are also issues that need to be overcome.

A third approach is to adsorb molecular hydrogen on the surface of a solid storage material. Hydrogen densities similar to liquefied hydrogen can be achieved with appropriate adsorbent materials. Some suggested adsorbents include activated carbon , nanostructured carbons including CNTs , MOFs , and hydrogen clathrate hydrate. Underground hydrogen storage is the practice of hydrogen storage in underground caverns , salt domes and depleted oil and gas fields. Large quantities of gaseous hydrogen have been stored in underground caverns by ICI for many years without any difficulties. Power to gas is a technology which converts electrical power to a gas fuel.

There are 2 methods, the first is to use the electricity for water splitting and inject the resulting hydrogen into the natural gas grid. The second less efficient method is used to convert carbon dioxide and water to methane , see natural gas using electrolysis and the Sabatier reaction. The excess power or off peak power generated by wind generators or solar arrays is then used for load balancing in the energy grid.

Using the existing natural gas system for hydrogen Fuel cell maker Hydrogenics and natural gas distributor Enbridge have teamed up to develop such a power to gas system in Canada.

Hydrogen economy

A natural gas network may be used for the storage of hydrogen. Before switching to natural gas , the German gas networks were operated using towngas , which for the most part consisted of hydrogen. The use of the existing natural gas pipelines for hydrogen was studied by NaturalHy [73]. The hydrogen infrastructure would consist mainly of industrial hydrogen pipeline transport and hydrogen-equipped filling stations like those found on a hydrogen highway.

Hydrogen stations which were not situated near a hydrogen pipeline would get supply via hydrogen tanks , compressed hydrogen tube trailers , liquid hydrogen trailers , liquid hydrogen tank trucks or dedicated onsite production. Because of hydrogen embrittlement of steel, and corrosion [74] [75] natural gas pipes require internal coatings or replacement in order to convey hydrogen. Techniques are well-known; over miles of hydrogen pipeline currently exist in the United States.

Although expensive, pipelines are the cheapest way to move hydrogen. Hydrogen gas piping is routine in large oil-refineries, because hydrogen is used to hydrocrack fuels from crude oil. Hydrogen piping can in theory be avoided in distributed systems of hydrogen production, where hydrogen is routinely made on site using medium or small-sized generators which would produce enough hydrogen for personal use or perhaps a neighborhood.

In the end, a combination of options for hydrogen gas distribution may succeed. While millions of tons of elemental hydrogen are distributed around the world each year in various ways, bringing hydrogen to individual consumers would require an evolution of the fuel infrastructure. The same study however, shows that building the infrastructure in a systematic way is much more doable and affordable than most people think.

For example, one article has noted that hydrogen stations could be put within every 10 miles in metro Los Angeles, and on the highways between LA and neighboring cities like Palm Springs, Las Vegas, San Diego and Santa Barbara, for the cost of a Starbuck's latte for every one of the 15 million residents living in these areas. In a future full hydrogen economy, primary energy sources and feedstock would be used to produce hydrogen gas as stored energy for use in various sectors of the economy.

Producing hydrogen from primary energy sources other than coal, oil, and natural gas, would result in lower production of the greenhouse gases characteristic of the combustion of these fossil energy resources. One key feature of a hydrogen economy would be that in mobile applications primarily vehicular transport energy generation and use could be decoupled. The primary energy source would need no longer travel with the vehicle, as it currently does with hydrocarbon fuels.

Instead of tailpipes creating dispersed emissions, the energy and pollution could be generated from point sources such as large-scale, centralized facilities with improved efficiency. This would allow the possibility of technologies such as carbon sequestration , which are otherwise impossible for mobile applications. Alternatively, distributed energy generation schemes such as small scale renewable energy sources could be used, possibly associated with hydrogen stations. Aside from the energy generation, hydrogen production could be centralized, distributed or a mixture of both.

While generating hydrogen at centralized primary energy plants promises higher hydrogen production efficiency, difficulties in high-volume, long range hydrogen transportation due to factors such as hydrogen damage and the ease of hydrogen diffusion through solid materials makes electrical energy distribution attractive within a hydrogen economy. In such a scenario, small regional plants or even local filling stations could generate hydrogen using energy provided through the electrical distribution grid. While hydrogen generation efficiency is likely to be lower than for centralized hydrogen generation, losses in hydrogen transport could make such a scheme more efficient in terms of the primary energy used per kilogram of hydrogen delivered to the end user.

The proper balance between hydrogen distribution and long-distance electrical distribution is one of the primary questions that arises about the hydrogen economy. Again the dilemmas of production sources and transportation of hydrogen can now be overcome using on site home, business, or fuel station generation of hydrogen from off grid renewable sources.

Distributed electrolysis would bypass the problems of distributing hydrogen by distributing electricity instead. It would use existing electrical networks to transport electricity to small, on-site electrolysers located at filling stations. However, accounting for the energy used to produce the electricity and transmission losses would reduce the overall efficiency. Natural gas combined cycle power plants , which account for almost all construction of new electricity generation plants in the United States, generate electricity at efficiencies of 60 percent or greater.

The distributed production of hydrogen in this fashion would be expected to generate air emissions of pollutants and carbon dioxide at various points in the supply chain, e. Such externalities as pollution must be weighed against the potential advantages of a hydrogen economy. One of the main offerings of a hydrogen economy is that the fuel can replace the fossil fuel burned in internal combustion engines and turbines as the primary way to convert chemical energy into kinetic or electrical energy; hereby eliminating greenhouse gas emissions and pollution from that engine.

Although hydrogen can be used in conventional internal combustion engines, fuel cells, being electrochemical , have a theoretical efficiency advantage over heat engines. Fuel cells are more expensive to produce than common internal combustion engines. Some types of fuel cells work with hydrocarbon fuels, [78] while all can be operated on pure hydrogen. In the event that fuel cells become price-competitive with internal combustion engines and turbines, large gas-fired power plants could adopt this technology.

Hydrogen gas must be distinguished as "technical-grade" five nines pure, Fuel cells require high-purity hydrogen because the impurities would quickly degrade the life of the fuel cell stack. Much of the interest in the hydrogen economy concept is focused on the use of fuel cells to power electric cars. Current hydrogen fuel cells suffer from a low power-to-weight ratio.

The economic viability of fuel cell powered vehicles will improve as the hydrocarbon fuels used in internal combustion engines become more expensive, because of the depletion of easily accessible reserves or economic accounting of environmental impact through such measures as carbon taxes. Other fuel cell technologies based on the exchange of metal ions e. Since the State of the Union address, when the notion of the hydrogen economy came to national prominence in the United States , there has been a steady chorus of naysayers. Most recently, in , Lux Research, Inc.

An accounting of the energy utilized during a thermodynamic process, known as an energy balance, can be applied to automotive fuels. Additional energy will be required to liquefy or compress the hydrogen, and to transport it to the filling station via truck or pipeline. The energy that must be utilized per kilogram to produce, transport and deliver hydrogen i. Another grid-based method of supplying hydrogen would be to use electrical to run electrolysers.

However, as noted above, hydrogen can be produced from a number of feedstocks, in centralized or distributed fashion, and these afford more efficient pathways to produce and distribute the fuel. A study of the well-to-wheels efficiency of hydrogen vehicles compared to other vehicles in the Norwegian energy system indicates that hydrogen fuel-cell vehicles FCV tend to be about a third as efficient as EVs when electrolysis is used, with hydrogen Internal Combustion Engines ICE being barely a sixth as efficient.

Hydrogen has been called one of the least efficient and most expensive possible replacements for gasoline petrol in terms of reducing greenhouse gases; other technologies may be less expensive and more quickly implemented. However, the technologies face very difficult challenges, in terms of cost, performance and policy.

That means that whatever the mix proportion between air and hydrogen, a hydrogen leak will most likely lead to an explosion, not a mere flame, when a flame or spark ignites the mixture. This makes the use of hydrogen particularly dangerous in enclosed areas such as tunnels or underground parking.

Hydrogen is odorless and leaks cannot be detected by smell. Hydrogen codes and standards are codes and standards for hydrogen fuel cell vehicles , stationary fuel cell applications and portable fuel cell applications. There are codes and standards for the safe handling and storage of hydrogen, for example the standard for the installation of stationary fuel cell power systems from the National Fire Protection Association. Codes and standards have repeatedly been identified as a major institutional barrier to deploying hydrogen technologies and developing a hydrogen economy.

To enable the commercialization of hydrogen in consumer products, new model building codes and equipment and other technical standards are developed and recognized by federal, state, and local governments. One of the measures on the roadmap is to implement higher safety standards like early leak detection with hydrogen sensors. It is expected that the general public will be able to use hydrogen technologies in everyday life with at least the same level of safety and comfort as with today's fossil fuels.

There are many concerns regarding the environmental effects of the manufacture of hydrogen. Hydrogen is made either by electrolysis of water , or by fossil fuel reforming. Reforming a fossil fuel leads to a higher emissions of carbon dioxide compared with direct use of the fossil fuel in an internal combustion engine. Similarly, if hydrogen is produced by electrolysis from fossil-fuel powered generators, increased carbon dioxide is emitted in comparison with direct use of the fossil fuel. Using renewable energy source to generate hydrogen by electrolysis would require greater energy input than direct use of the renewable energy to operate electric vehicles, because of the extra conversion stages and losses in distribution.

Hydrogen as transportation fuel, however, is mainly used for fuel cells that do not produce greenhouse gas emission, but water. There have also been some concerns over possible problems related to hydrogen gas leakage. It has been hypothesized that if significant amounts of hydrogen gas H 2 escape, hydrogen gas may, because of ultraviolet radiation, form free radicals H in the stratosphere.

These free radicals would then be able to act as catalysts for ozone depletion. A large enough increase in stratospheric hydrogen from leaked H 2 could exacerbate the depletion process. However, the effect of these leakage problems may not be significant.

In , the production of unit of hydrogen fuel by steam reformation or electrolysis was approximately 3 to 6 times more expensive than the production of an equivalent unit of fuel from natural gas. The energy content of these fuels is not a product of human effort and so has no cost assigned to it. Only the extraction, refining, transportation and production costs are considered.

On the other hand, the energy content of a unit of hydrogen fuel must be manufactured, and so has a significant cost, on top of all the costs of refining, transportation, and distribution. Systems which use renewably generated electricity more directly, for example in trolleybuses , or in battery electric vehicles may have a significant economic advantage because there are fewer conversion processes required between primary energy source and point of use.

The barrier to lowering the price of high purity hydrogen is a cost of more than 35 kWh of electricity used to generate each kilogram of hydrogen gas. Hydrogen produced by steam reformation costs approximately three times the cost of natural gas per unit of energy produced. Demonstrated advances in electrolyser and fuel cell technology by ITM Power [99] are claimed to have made significant in-roads into addressing the cost of electrolysing water to make hydrogen. Cost reduction would make hydrogen from off-grid renewable sources economic for refueling vehicles.

Hydrogen pipelines are more expensive [] than even long-distance electric lines. Hydrogen is about three times bulkier in volume than natural gas for the same enthalpy. Hydrogen accelerates the cracking of steel hydrogen embrittlement , which increases maintenance costs, leakage rates, and material costs. The difference in cost is likely to expand with newer technology: Setting up a hydrogen economy would require huge investments in the infrastructure to store and distribute hydrogen to vehicles. In contrast, battery electric vehicles , which are already publicly available, would not necessitate immediate expansion of the existing infrastructure for electricity transmission and distribution.

Power plant capacity that now goes unused at night could be used for recharging electric vehicles. Different production methods each have differing associated investment and marginal costs. The energy and feedstock could originate from a multitude of sources, i. The distribution of hydrogen for the purpose of transportation is currently being tested around the world, particularly in Portugal , Iceland , Norway , Denmark , Germany , California , Japan and Canada , but the cost is very high. Some hospitals have installed combined electrolyser-storage-fuel cell units for local emergency power.

These are advantageous for emergency use because of their low maintenance requirement and ease of location compared to internal combustion driven generators.

Iceland has committed to becoming the world's first hydrogen economy by the year Presently, it imports all the petroleum products necessary to power its automobiles and fishing fleet. Iceland has large geothermal resources, so much that the local price of electricity actually is lower than the price of the hydrocarbons that could be used to produce that electricity. Iceland already converts its surplus electricity into exportable goods and hydrocarbon replacements.

Iceland is also developing an aluminium-smelting industry. Aluminium costs are driven primarily by the cost of the electricity to run the smelters. Either of these industries could effectively export all of Iceland's potential geothermal electricity.

Neither industry directly replaces hydrocarbons. For more practical purposes, Iceland might process imported oil with hydrogen to extend it, rather than to replace it altogether. CUTE, [] operating hydrogen fueled buses in eight European cities. A pilot project demonstrating a hydrogen economy is operational on the Norwegian island of Utsira. The installation combines wind power and hydrogen power. In periods when there is surplus wind energy, the excess power is used for generating hydrogen by electrolysis.

The hydrogen is stored, and is available for power generation in periods when there is little wind. United States has a hydrogen policy with several examples. When excess electricity is available after the batteries are full, hydrogen is generated by electrolysis and stored for later production of electricity by fuel cell. The trial began in September and concluded in September

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