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By
American Bobcat - Florin FODOR
H –
The Drawbacks of Hydrogen Does Hydrogen has any drawbacks which prevent us to have hydrogen economy? Striclty speaking about Hydrogen as fuel, the answer is NO. Elemental Hydrogen is the almost the perfect fuel. Hydrogen fuel is the most promising alternative fuel for the future. It has a high calorific value, It yields almost double the energy provided by jet fuels and its only combustion product is water vapor. A kilogram of hydrogen contains more than twice the energy of a kilogram of gasoline, diesel, or natural gas, (for instance hydrogen holds 33 kWh/kg of gross energy vs. diesel which contains 11.976 kWh/kg of gross energy). Hydrogen is a clean-burning zero-carbon, hence is 100% pollution free. The hydrogen fuel that launches NASA rockets into space and provides electrical power via fuel cells, produces only one waste product: water so pure the astronaut crew can even drink it. No doubt, Hydrogen has enormous potential. Lately, the fossil fuel industry is continuously promoting hydrogen of all kinds as a low-carbon replacement for all sorts of uses of fossil fuels—from powering vehicles and heavy industry to heating buildings and other domestic uses. Hydrogen fuel cells and hydrogen-burning gas turbines are already available for use. Yet somehow things still don’t go as expected with hydrogen. Many hydrogen projects will only lock us in to continued fossil fuel use and additional investments in fossil fuel infrastructure. The first cars powered by hydrogen fuel cells hit the market in 2015, promising cleaner air and a healthier planet. But if you have yet to see one on the road, you’re not alone. At the status for year 2023, there are fewer than 16,000 in the U.S. (most of them in California). So then why hasn’t hydrogen gone mainstream as an alternative to gasoline-powered engines so that we can really have a hydrogen economy? Is it all just hype? No, it is not! The drawback is not Hydrogen itself. Instead, it is the technology we currently have in order to produce, store and efficiently use Hydrogen as fuel. We don’t yet have a large hydrogen economy because there are a handful of factors which have limited the hydrogen uptake around the world. For the current status in 2023-2024, despite being light, energy-dense and readily available, hydrogen has yet to establish itself as a widely used fuel source. The main factors which still limit hydrogen to be used as domestic fuel are briefly reviewed next. These are:
Hydrogen is the lightest known element and in its natural elemental form is gas; Being light is also less dense so at standard pressure and temperature, hydrogen gas occupies large space. It’s not easy to contain conveniently. For long-term storage, hydrogen must be converted to a liquid, a process which can be more expensive than producing the hydrogen itself. Progress in this matter has been made but still more needs to be done. Storing hydrogen as a gas requires high-pressure tanks, and storing it as a liquid requires maintaining cryogenic (very cold) temperatures. Hence regardless in which state is, hydrogen remains difficult to handle. If hydrogen were to replace gas in the global economy, it would require 3 to 4 times more storage infrastructure at a cost of around $640 billion by 2050, to provide the same level of energy security as the world would have with gas.
PRODUCTION COSTS Due to its dramatically high buoyancy unlike other gases, hydrogen is not readily available in the atmosphere. That’s also because it’s highly reactive and forms compound molecules with other elements (such as oxygen and carbon). There’s virtually no pure hydrogen resources on Earth. However since its 1st discovery in 1766 by the chemist Henry Cavendish, up to present day different effective ways to separate hydrogen from its compounds have been developed. In spite of many technology improvements, unfortunately today more than 96% of hydrogen production still derives from non-renewable sources, effectively cancelling out its green properties. Nowadays, most hydrogen is made from methane [natural gas] in a process that produces carbon dioxide (CO2) and other greenhouse gases. Hydrogen can also be made from water using electrolysis, but that requires electrical energy. This is a very costly process and time consuming and to get electrical energy from it, we’re back to burning fossil fuels. This is one of the main reason why we don’t drive yet many hydrogen-fueled cars worldwide. Current hydrogen vehicles use fuel cells to convert the chemical energy to power, which is clean enough. Fuel cells are appealing because, in theory, they overcome efficiency limitations associated with traditional internal combustion engines. Yet these fuel cells are very costly because they are complex units and require expensive materials such as platinum. This is another reason why hydrogen remains limited in use at large scale. EFFICIENCY Currently hydrogen-powered cars are less advantageous than electric-powered for cars. The battery-powered electric motor is now the most efficient system because it converts 80% of the electricity in the battery into mechanical energy. What’s more, it is currently cheaper to charge an electric car than to refill on hydrogen. Hydrogen also comes in different version depending on how it’s produced. For instance Grey Hydrogen (a “dirty” process) costs €1-2 per kg, while Green Hydrogen (a “clean” process) costs €5-7 per kg. If the “green” advantage of using hydrogen is preserved also during the production stage, refilling a car must only involve green hydrogen. And suppliers sell green hydrogen at a price of around €14 per kg, which can fall to €9 per kg where infrastructure is more developed such as in Germany. For now in terms of availability, electrical charged cars the best option. However the hydrogen-powered engine remains much more efficient than a conventional petrol/diesel engine. Diesel offers a small financial advantage over hydrogen in terms of availability, but the enormous environmental benefits of hydrogen would offset the higher cost. One thing is certain: hydrogen is for now less beneficial for light road transport compared to electric power from renewable sources. Industry has been pushing for Blue hydrogen development with the dubious argument that investing in sub-optimal (or harmful) hydrogen infrastructure today might allow the deployment of green hydrogen in the future. In reality, the cost of green hydrogen will only decline based on advancements in electrolyzer technology and continued reduction in the costs of wind and solar power, but not based on gray or blue or any other different type of hydrogen development. SAFETY CONCERNS Hydrogen is highly explosive in a large range of concentrations (from 4% to 75%, hence using it as domestic fuel is very dangerous. Even a small spark from electrostatic discharge can cause uncontrolled combustion leading to huge explosions. And hydrogen does not burn at a slow rate. For this reason the need for onboard hydrogen fuel tanks has created safety concerns and limited the uptake of hydrogen Fuel Cell Electric Vehicles (FCEVs). However some auto makers such as Toyota, have been quick to rebuke these concerns, maintaining that FCEVs are just as safe as their petrol and diesel-powered counterparts. The company’s latest hydrogen-powered model, the Toyota Miraj, has been rigorously tested to offer motorists rock-solid safety credentials. So there is much hope. The future in this direction of technology developments is highly optimistic. Additionally, any hydrogen leakage could undermine the benefits of green hydrogen and increase the lifecycle emissions of other types of hydrogen because hydrogen is an indirect greenhouse gas—meaning it combines with other compounds in the atmosphere to cause warming—that is 5 times more potent than carbon dioxide over a 100-year timeframe. If we learn how to effectively control hydrogen leakage then we are on the right track. The progress made here so far, is also very promising. POLLUTION Here we have 2 big drawbacks.
1.Upstream emissions = As already mentioned, we know that when combined with oxygen to generate electricity, hydrogen emits water and heat as its only by-products. This gives it incredible potential as a sustainable and climate-friendly fuel. However, when upstream processes are factored in the environmental credentials of hydrogen as a fuel source plummet. There are many ways to extract hydrogen, but the cheapest and therefore most common one is Steam Methane Reforming (SMR). This process to produce hydrogen is using either coal or natural gas as feedstocks. Both emit harmful by-products into the atmosphere, including enormous amounts of carbon dioxide (CO2). So, while hydrogen itself is eco-friendly the processes used to isolate the chemical element have a significant environmental footprint. Hydrogen produced by SMR is known as “grey hydrogen” Grey hydrogen It costs less than other H colors, but its impact on the environment is so great that 10 kilos of carbon dioxide are produced for every kilo of hydrogen obtained. World hydrogen production is about 70/75 million tonnes, with a waste of almost 1 billion tonnes of carbon dioxide.
Of course hydrogen can be also produced completely clean by electrolysis in which solar-based electricity can be used to split water into H and O, this version being known as “green hydrogen”. Yet Since solar provides only a fraction of the total electricity generated. Diverting solar-based electricity to make hydrogen doesn’t reduce greenhouse gas emissions. That could only change if solar-based electricity is ramped up in the future. The biggest challenge is to produce clean hydrogen (green) at an affordable cost. The production of hydrogen through steam methane reforming (SMR) besides carbon dioxide, it produces other emissions that are known to be harmful, including NOx (nitrogen oxides), particulate matter, carbon monoxide (CO), and volatile organic compounds (VOCs). So if it is not produced using renewable sources, hydrogen pollutes. Hydrogen does not necessary produce carbon emissions when burned at end use. But if hydrogen is blended with methane gas (CH4) at a power plant, the carbon emissions from that power plant will be lower. Hydrogen has a lower energy density than gas, meaning it takes a larger volume of blended hydrogen and methane to provide the same energy input as an equal volume of gas. Because of this, a blend of 30% hydrogen + 70% gas by volume only results in a 13% decrease in carbon emissions at end-use. To date, more than 96% of the hydrogen used is grey. While this “dirty” hydrogen is not yet widely used as a fuel, its use in industrial processes is widespread, in particular as a key ingredient in the tens of millions of tons of ammonia (NH3)-based fertilizers produced annually. Without these fertilizers, global food production would collapse. In this sense, we already have a hydrogen economy. Controlling nitrogen oxide (NO) emissions is also a concern. When grey hydrogen is combusted, it does not produce carbon emissions, but it does produce NOx emissions up to 6 times worse than those released by methane combustion. NOx can cause serious health effects, including asthma and increased chance of respiratory infections; NOx is also a precursor to particulate matter and ozone, which harm the respiratory system. While there are methods of controlling NOx emissions at gas power plants, those technologies are only effective at controlling NOx at a blend of 30% hydrogen or less. 2.Carbon dioxide emissions are costing the world a great deal, but those who produce them pay nothing. And clean hydrogen is clearly more expensive than dirty hydrogen. Prospects for carbon pricing are uncertain, so we need to find ways to make clean hydrogen economically competitive even in the absence of a fair price for carbon. On the other hand, if carbon dioxide does get properly priced, early adopters of clean hydrogen technologies will gain a huge economic advantage. This can provide a major motivation for experimentation and risk-taking in this area. LACK OF SCALABLE TECHNOLOGY Lack of hydrogen vehicle fueling station infrastructure has also prevented uptake. The United States operates around 50 hydrogen vehicle fuelling stations, almost all located in California. This deters motorists from investing in hydrogen-powered vehicles and in turn, discourages auto manufacturers from producing hydrogen-powered cars. Besides, Hydrogen fuel cells and gas turbines still need work. Hydrogen fuel cells and gas turbines are the two principal means of turning hydrogen fuel back into energy. A hydrogen fuel cell is a battery-like device that turns hydrogen and oxygen directly into electricity, with water as a byproduct. For hydrogen fuel cells, there is considerable room for improvement in the areas of cost, efficiency, and durability. Hydrogen fuel cells have been used to power buses, trains, and submarines; A gas turbine is a machine that turns fuel and oxygen into the kinetic energy of exhaust gases and a rotating shaft; the kinetic energy then drives another machine, like an electrical generator or an airplane (a jet engine is one type of gas turbine). For hydrogen gas turbines, the remaining issues are more narrowly focused on durability — while gas turbines are an extremely well-established technology, hydrogen burns hotter than the methane or kerosene with which they are usually fueled. Gas turbines that can burn a mix of methane and hydrogen are already widespread. Bringing these technologies to full maturity is now a matter of engineering tweaks, trial and error, and the marketplace demand needed to drive them.
Fuel cells and gas turbines come in a wide range of sizes — fuel cells can power golf carts or skyscrapers; gas turbines can power helicopters or cities. There are no theoretical reasons why these devices cannot become just as durable, efficient, and cost-effective as the hydrocarbon-burning machines they will replace. Anyway, we need to try out multiple combinations of energy sources such as wind, photovoltaics, and concentrated solar power, with hydrogen production technologies such as electrolysis and pyrolysis.
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