- What energy sources can be used to produce hydrogen?
- Hydrogen can be obtained from any form of primary energy whether renewable or conventional. Natural gas is the primary feedstock. It is used in a process called steam reforming to generate the vast majority (75 percent) of the world’s industrial hydrogen gas. This is because steam reforming is a very efficient, proven process and natural gas is readily available. Linde has already built over 200 hydrogen production plants across the globe. The Group’s strategic objective, however, is to increase the regenerative share of the hydrogen mix required to power our mobility needs.
- Isn’t the technology behind hydrogen production too exotic to ever become a serious contender?
- The technology for producing hydrogen has been around for a long time. We have been generating hydrogen on an industrial scale for over one hundred years now and large volumes of this gas are used in many industrial processes today. Over 50 million tonnes of hydrogen are currently produced each year. A freight train carrying this much hydrogen would stretch almost four times around the earth’s equator. Linde is a global leader in the production and distribution of hydrogen and has in-depth experience in safe handling practices. Today, the vast majority of hydrogen is used in refineries to desulphurise petrol and diesel. So it is already making a key – and growing – contribution to the production of cleaner fuels. Large volumes of hydrogen are also required in the chemical and metal processing industries.
- Doesn’t producing hydrogen require more energy than the energy subsequently released by the hydrogen?
- When judging the efficiency of hydrogen sourced from natural gas, the entire production and consumption chain has to be factored into the equation. A hydrogen fuel cell is highly efficient. This means that hydrogen matches or exceeds the energy efficiency of conventional transport fuels. However, crude oil reserves are dwindling and will no longer be available in sufficient amounts to power vehicles for the next generation. And even though today’s combustion engines are becoming cleaner and more efficient, they continue to emit CO 2 and other harmful substances such as nitrogen oxides and particulate matter. Hydrogen offers us a route to oil-free mobility, for generations to come. It will improve the quality of air in cities and play an important role in reducing and – ultimately – eliminating CO 2 emissions.
- When can we expect true ‘green’ hydrogen?
- Linde already provides its customers with climate-neutral and green hydrogen on request. Through the purchase of carbon credits, Linde is able to supply hydrogen for mobile applications that classifies as climate neutral. And green hydrogen is already a reality in Magog ( Quebec, Canada), where The Linde Group uses hydroelectric sources to produce enough hydrogen to power over 35,000 fuel-cell vehicles every day. Linde aims to significantly increase the proportion of hydrogen it produces from sustainable energy sources in the long term. Which is why the company is breaking new ground in regenerative production processes as it explores possibilities such as algae and biomass as the feedstock. Conventional hydrogen production is already a more climate-friendly option, bringing greater diversity to our primary energy mix in road transport. A car powered by conventional hydrogen derived from natural gas reduces the well-to-wheel carbon footprint of a modern diesel car by up to 30 percent. To realise zero-emissions mobility with economically viable, regenerative hydrogen, however, we must also be able to generate hydrogen from electricity or biomass, for example, and explore the possibilities of carbon capture.
- Using electrolysis to produce hydrogen requires water. Will this conflict with drinking water supplies?
- Securing water supplies is one of the greatest challenges facing mankind. Between 1 and 2.5 litres of water are required to produce just one litre of petrol. The generation and consumption of hydrogen produced through electrolysis is a closed cycle. The feedstock water is broken down into hydrogen and oxygen. During ‘combustion’ in a hydrogen-powered car, both gases recombine to form water. In other words, no water is actually consumed, making this a very appealing concept.
- There is a lot of support for battery electric vehicles at the moment. Do we even need hydrogen fuel at all?
- The electrification of cars will play a crucial role in the transition to low-emission road transport. Vehicles with fuel cells and batteries are just two examples of electrification and both models complement each other very well. Both systems have proven to be technically viable, so it is now a matter of commercialising competitive, appealing products. Approximately one third of the components used in battery-operated and fuel-cell cars are the same, so progress and development in one area is beneficial to the other. However, there are big differences in range and refuelling times. Cars powered exclusively by electric batteries currently have very limited ranges. Even looking to the future, lithium-ion batteries are not expected to take cars further than 200 kilometres on a single charge until 2020 at the earliest. Recharging times are also less than ideal for consumers. Today’s drivers face an average wait of up to seven hours. Even optimistic estimates for turbo charging exceed the half-hour mark. In contrast, hydrogen-powered vehicles can already be fully refuelled in around three minutes – a similar timeframe to diesel and petrol cars. In addition, pre-series H 2 cars already run for almost 700 kilometres on a single tank.
- How much does hydrogen cost?
- A kilogram of hydrogen currently costs around six to fifteen euros. When used in conjunction with a fuel cell, this corresponds to a range of around 100 kilometres and is thus comparable to the cost of conventional fuels running in regular engines. However, the price may fluctuate greatly depending on a number of factors. Hydrogen is produced, transported and sold regionally and – unlike oil – does not have a regulated global market price. The cost of hydrogen is currently heavily dependent on variables such as factor costs, production path, demand, geographical location and the degree of purity required. Since the technology used to produce hydrogen as a fuel is still very new, there is vast scope for cost efficiencies in the long term. Hydrogen that is produced and consumed on an industrial scale is considerably cheaper than hydrogen produced and offered on a limited scale at fuelling stations set up for demo projects. In the long term, the price point of hydrogen at fuelling stations (including tax) must be attractive to drivers of hydrogen-powered cars. The diversification potential of hydrogen is another one of its main strengths. Unlike oil, which has cornered 98 percent of road transport, hydrogen can be generated from a variety of sources.
- When will hydrogen be able to compete with other fuels?
- Hydrogen fuel is revolutionising a century-old tradition in automotive technology. It therefore makes sound environmental and economic sense to expand the hydrogen footprint gradually. The technology enabling the hydrogen fuel chain is still young and therefore offers huge scope for cost efficiencies, so we will see price drops in the medium term. Today, the price of untaxed hydrogen can already compete with conventional fuels. Taking all factors into consideration, the long-term cost of fuel-cell cars will be lower than conventional technologies.
- How mature is hydrogen technology? And if it is sufficiently mature, why hasn’t it already been widely commercialised?
- Unlike the industrial sector, the mobility market for hydrogen is still in its infancy. Advances are taking place in the wider fields of production, storage and distribution for this market. At the same time, commercialisation of hydrogen calls for the development and standardisation of efficient fuelling processes and the evolution of automotive technologies. In recent years, significant progress has been made in the move towards market-ready systems and products, in terms of both vehicle design and the supporting infrastructure. Public hydrogen fuelling stations, however, will only be economically viable once there are a sufficient number of hydrogen-fuelled cars on the road. To drive progress in this area, Daimler, EnBW, Linde, OMV, Shell Deutschland, Total Deutschland, Vattenfall Europe and the National Organisation for Hydrogen and Fuel Cell Technology (NOW) signed a Memorandum of Understanding to form the ‘H 2 Mobility’ initiative. The aim of these founding members is to dovetail the market availability of hydrogen vehicles with the emergence of a supporting infrastructure. Similar developments are also taking place in Japan and the US (particularly in California).
- How many hydrogen fuelling stations are there already?
- Around two hundred hydrogen fuelling stations are currently in operation worldwide. Germany alone already has almost thirty stations, some of which are open to the public, making Germany the hydrogen pioneer in Europe.
- How much would it cost to build an infrastructure with full coverage?
- The Linde Group estimates that initial nationwide coverage in Germany would involve infrastructure costs of around EUR 1.7 billion, which would create approximately 1,000 fuelling stations. Around EUR 3 billion in investments would be required for a Europe-wide infrastructure of fuelling stations by 2020. This was one of the findings of Europe’s most extensive study to date on the prospects of various drivetrain concepts for personal mobility presented on 8 November 2010 in Brussels.
- Is hydrogen a more dangerous fuel than petrol?
- Many pilot and demo fuelling stations around the world have shown that hydrogen can be handled safely as a fuel. It is the lightest element in the world and volatilises very rapidly in air, giving it a major advantage over petrol, which dissipates more slowly and is heavier than air. Petrol therefore stays on the ground longer, where the threat of ignition is highest. Petrol and hydrogen also burn differently. If liquid petrol leaks, spreads onto a surface and burns, it produces a very broad flame that emits a large amount of heat. In contrast, hydrogen burns with a narrow almost perpendicular flame that does not emit much heat. Unlike a bright petrol flame, however, a pure hydrogen flame is difficult to see in daylight. Hydrogen’s overall ignition properties are generally more favourable than today’s common energy carriers. Petrol’s flammability limit (0.6 volume percent) and explosion limit (1.1 volume percent) are very close together, which means that when petrol ignites, there is almost always the danger of explosion. Hydrogen’s flammability limit of 4 volume percent and its explosion limit of 18 percent are much further apart. At 0.24 millijoules, however, petrol’s minimum ignition energy threshold is significantly higher than hydrogen’s– although the energy in a spark is still sufficient to ignite petrol. And petrol’s relatively low auto-ignition (temperature 220 to 280 degrees Celsius) also means that it can ignite on contact with hot metal parts such as a catalytic converter or exhaust manifold. This is not the case with hydrogen, which has an auto-ignition temperature of 585 degrees Celsius. Extensive tests carried out for example by the German testing, inspection and certification authority, TÜV Süd, have shown that hydrogen-powered cars are not more dangerous than conventional vehicles.
- What steps are being taken to make hydrogen available for safe, daily use?
- Safety is a global issue in the gas industry. Leading manufacturers across the world come together to continually improve standards and make systems even safer. The task forces formed under the umbrella of the European Industrial Gases Association (EIGA) are a prime example of how companies come together to discuss safety issues and develop joint solutions. Plants and components are also subject to a large number of studies and tests to keep inherent risks posed by all energy carriers to an absolute minimum. In short, safety is always the number one priority.
- Is it true that hydrogen makes metals brittle?
- It is true that hydrogen can cause material fatigue. This phenomenon, known as hydrogen embrittlement, was discovered at the end of the 19th century and has been the subject of research ever since. Today’s engineers have this problem under control. Numerous institutes, for example, the German Federal Institute for Materials Research and Testing (BAM), are always willing to advise and help. If this were not the case, it would be impossible to transport hydrogen safely using steel cylinders, tanks or pipelines. Today, we know which materials are suitable and what stresses they can be subjected to.
- Isn’t the storage of hydrogen a problem? How can hydrogen be stored?
Hydrogen (H2) is a highly volatile gas that can escape through the smallest of leaks. However, industry wide work in material technology, welding, valve technology and screwed joints means hydrogen can be handled and stored safely – this has been proven over the last decades by the industrial gas industry.
Hydrogen can be stored as a gas, a liquid or in solid materials. It has a high gravimetric storage capacity but a low volumetric one. Therefore to store a reasonable amount it either has to be compressed or liquefied to cryogenic temperatures, i.e. -253 °C. Hydrogen can also be stored at low pressure in the form of metal hydrides, which are used in various niche applications.
Small volumes of compressed hydrogen gas are commonly stored in pressurised cylinders at either 200 or 300 bar with between 10 and 50 litres of volume per cylinder. They are mainly used for laboratory and welding applications and also as small refuelling solutions for the demonstration of hydrogen-powered vehicles.
A pressure vessel is the most suitable solution for storing medium amounts of hydrogen. These are widely used for many different gases and are variable in volume and pressure level. This storage technology is suitable for small and medium hydrogen fuelling stations as well as industrial customers who require medium amounts of hydrogen for their production processes.
Hydrogen delivered in liquid form can be stored in volumes of up to 70,000 litres in super-insulated tanks - Even though a central liquefaction of hydrogen consumes more energy than a central compression, the advantage is a higher energy density due to the reduced volume and therefore the need for less storage – for certain locations such as fuelling stations this is a key factor.
Finally, the increase in unsteady wind and solar electricity production has led to excess energy that is not matching the demand of the grid. This calls for a storage solution for this excess energy until it is required.
One way in which the grid can be balanced is through the electrolysis of water. The water is split into hydrogen and oxygen with the energy stored in chemical form as hydrogen. These large volumes cannot simply be stored in tanks; instead, hydrogen is stored in salt caverns that can hold thousands of cubic metres of gas. Comparable facilities already exist in the United Kingdom and in the south of the United States. Depending on the geological conditions these caverns can store more energy than any other known energy storage technology.