Since the UN Climate Change Conference in Paris in December 2015, which led to the international climate agreement, there have been far-reaching developments in the sustainability of the global energy supply. More and more countries are turning to hydrogen. What can hydrogen contribute to the energy transition? We asked Professor Ad van Wijk, Professor of Future Energy Systems at Delft University of Technology. “It’s both technically and economically feasible to produce enough fully circular energy around the world,” he states.
Has a lot been achieved in terms of innovations to tackle global warming since the Paris Climate Conference?
“Absolutely, but don’t forget that the developments go back much further than 2015. Scientists have been studying the effects of burning fossil fuels, carbon emissions and the use of greenhouse gases such as CFCs and methane for decades. Since the climate summit in Kyoto in 1997, the relationship between greenhouse gas emissions and climate change has become increasingly apparent. The IPCC reports are now very clear in that area as well. An important achievement at the Paris conference was the fact that agreement was reached on the need to restrict the rise in the global temperature to no more than 1.5 to 2 degrees centigrade, and it was decided that each country would be given the latitude to formulate its own policies to combat further global warming. Since then, I have seen a rising sense of urgency, not only among politicians but also among the younger generation and, perhaps to an even greater extent, in the business world. I have frequent contacts with the leading executives of major companies and I have seen how skepticism about climate change has virtually disappeared in the business world. People are now clearly convinced that business models based on the use of fossil fuels are not sustainable in the long term. One of the effects of the Paris summit is that people are now thinking seriously about innovations that go further than quasi-environmental strategies or a ‘green’ image. My approach puts a strong emphasis on the opportunities afforded by hydrogen. I believe that the transition to hydrogen, in all its forms, is the way forward towards truly circular energy.”
Can you explain how hydrogen is made?
“Let me say first of all that hydrogen is not a source of energy. It is an energy carrier that you can produce from sources such as oil, natural gas and coal. You can produce hydrogen gas by converting hydrocarbons in a chemical reaction that releases CO2. That approach is used, for example, to produce fertilizer (ammonia). Hydrogen gas is widely used in numerous applications, for example in refineries for the production of petrol. Approximately 800,000 tons of hydrogen gas is produced from natural gas annually in the Netherlands, of which 400,000 tons in the port of Rotterdam. With its large stocks of natural gas, the Netherlands has actually become the second largest producer of hydrogen in Europe after Germany. Depending on the approach used to process the released CO2, this type of hydrogen gas is usually referred to as ‘grey’ (CO2 is released to the air) or ‘blue’ (CO2 is captured and stored) hydrogen. What we are now focusing on is the production of ‘green hydrogen’, which does not result in any net release of CO2. Green hydrogen gas is made by converting electricity from solar and wind in a process known as electrolysis. In very simple terms: it’s made from ordinary water. Chemically, water consists of two elements: hydrogen and oxygen, or H2O. In short, electrolysis is a process that breaks water down into oxygen (O2) and hydrogen (H2) by sending an electrical current through it. The result is hydrogen gas - the most common gas in the universe. It is harmless and you can transport it safely through existing gas pipelines without many modifications being needed.”
And how can hydrogen be stored?
“That is one of the great benefits of hydrogen: you can store it more easily and cheaper than electricity. One of the major limitations of solar and wind energy is that the power you produce has to be used immediately: it is difficult to store in batteries, simply because there are no batteries with enough capacity for such large amounts of energy. And building them is not a serious option either because of the cost. But there are more affordable options for storing hydrogen. Some of them resemble our current approaches for storing oil and gas in tanks. But hydrogen can also be stored in salt caverns and specific empty gas fields may also be an option. Hydrogen is already stored in salt caverns at several locations around the world, and very cheaply. That means we can produce electricity or heat using the stored hydrogen whenever we need it. Green hydrogen is a fully circular energy carrier: you produce electricity from water, releasing oxygen to the air. Exactly the same amount of oxygen is used and the same amount of water is left at the end of the process, whether you use a boiler, furnace or gas turbine or chemically convert the hydrogen in a fuel cell to produce heat and electricity.”
How can you power an electric car with hydrogen?
“You use a fuel cell to power the car. It effectively reverses the process done by the electrolyzer. Hydrogen gas is combined in the fuel cell with oxygen from the air. That results in a chemical reaction which produces electricity and the only residual product is water. The electricity is routed to the car’s electric motor. This all eliminates the need for heavy batteries. Hydrogen-powered cars can cover a distance of one hundred kilometers with one kilo of hydrogen. The drive train of a fuel-cell electric vehicle is much more efficient than a diesel engine and there are no emissions of pollutants such as CO2, particulate matter and nitrogen-oxides.”
So are we seeing the end of cars and trucks with internal combustion engines?
“It looks like it. I believe that the future belongs to cars with electric motors powered by electricity from a battery or by converting hydrogen gas into electricity with a fuel cell. Electric cars have been used increasingly in recent years around the world. Most of them are battery electric cars at present but it is expected that we will have fuel-cell cars in the future that will produce electricity by converting hydrogen gas with oxygen from the air. The electricity released during that process drives the electric motor of the car. The ranges of these vehicles are increasing all the time: these cars can now manage between 400 and 600 kilometers. And filling the tank with hydrogen is just as quick as with petrol. As we speak, there are already more than eighty hydrogen filling stations across Germany. An alliance of Shell, Total and car manufacturers will build a total of 400 hydrogen fueling stations until 2023. All the car manufacturers are working on the further development of electric cars. Fuel cells are the most obvious option for large cars and certainly for vans, buses and trucks. Tests are already being conducted on inland shipping vessels that run on hydrogen.”
Limiting global warming
Can hydrogen contribute to achieving the target of limiting global warming to no more than two degrees?
“That is certainly possible in technical and economic terms. By converting green energy into hydrogen, we can limit global warming. However, we need a large-scale joint approach to production, transport and storage. So actually achieving the target depends on the political will to go down this road and how quickly the business sector and the public get behind it. If you’d asked me the same question five years ago, I wouldn’t have been so optimistic. But there has been an important development: the price of solar and wind energy has now fallen to such an extent that we can now keep the total costs of our energy supply manageable. Which is why so many parties are interested. The current cost of producing a kilowatt hour (kWh) of electricity at the right solar and wind sites is about 1.5-2.0 euro cents. But you have to do that in the right places. Morocco, for example. A new wind farm was recently opened there where costs can be kept to that level. A new solar farm in Dubai can produce for less than 1.5 euro cents. Even in Portugal, a recent tender for 1 GW solar has resulted in a price of 1.48 euro cents per kWh.”
Large scale required
“The technology and installation methods have progressed so far that low costs of this kind for electricity production are now a reality. By comparison, electricity from the most modern coal-fired power stations costs three times as much. Large energy companies expect the price of solar and wind to drop even further in the coming years to around 1 euro cent per kWh. But let me repeat: this is only possible with a large-scale approach and in locations with a lot of sun, such as the Sahara or Australia, or with a lot of strong winds, such as Patagonia, Kazakhstan or on the oceans. We don’t really have any locations like that in Europe. The returns from a wind turbine depend on wind strength. A wind turbine has to run at its maximum capacity for more than five thousand hours to get a return on the investment. That is hardly ever possible on land and that is why wind turbines on land are not usually viable without government subsidies. The same applies to solar panels: the climate in Northwest Europe is not really suitable and there is not enough space available. Just to give you an idea: a solar farm was opened recently in Dubai that has a capacity of 5,000 MW. By comparison, the largest solar farm in the Netherlands has a capacity of 50 MW. In an area like the Sahara, the conditions are right and it really is worth setting up large-scale systems there.”
Should Europe be abandoning the idea that we can produce our own sustainable energy?
“From the cost point of view, I think that’s fair to say. There aren’t enough possibilities in Europe for the large-scale production of green energy that will always be available. But the good news is that cheap, sustainable energy is available worldwide. By installing solar panels in a relatively small part of the Sahara, about eight percent of the desert, we can generate enough energy to supply the entire world with electricity. So there’s no space problem: the Sahara is almost twice the size of the whole of the European Union and hardly any people live there. Europe already imports more than 50% of its energy. The truth of the matter is that the conditions in Europe are such that wind turbines and solar panels are not efficient enough in this region. So it costs much more to produce energy in Europe than to import hydrogen from the Sahara through pipelines. In the area around the Red Sea, the onshore wind is at least as strong as in the North Sea, which means that large onshore wind farms can be built much more economically than our offshore wind farms. That is already happening in the Middle East: they use cheap power from solar farms in their own country and sell the oil and gas. Morocco recently set up an inter-ministerial working group to sell hydrogen as an export product, and countries such as New Zealand, Australia and Chile are also focusing on wind and solar as export products. Japan is opting for blue and green hydrogen as an alternative to nuclear energy, and China is already focusing on blue and green hydrogen extensively as well.”
So the main problem in Europe is that hydrogen gas can be produced relatively economically but not in adequate quantities where it is needed? Is transporting that energy actually the biggest challenge?
“That’s right. Transporting green power through cables over long distances involves power losses and costs more than hydrogen transport through pipelines. By converting electricity into hydrogen gas, you can reduce transport costs by a factor of ten or even twenty in comparison with electricity through cables. Even though you lose electricity in the conversion process, the savings in transport costs more than compensate for the losses. Scientists from, among other places, Delft University of Technology are now working on practical ways of putting this process into practice. They are working on a project in North Africa where water is being converted into hydrogen gas with electrolysis using electricity from solar farms in the Sahara. The gas is then transported to Rotterdam through an existing gas pipeline. There are even ideas for a transitional arrangement involving the installation of a pipeline with a smaller diameter inside the pipeline that is already in place for the transportation of hydrogen. But there are other ways to export hydrogen: you can liquefy it or convert it into ammonia using nitrogen from the air and then transport it by sea in tankers. Unlike hydrogen gas, liquid hydrogen or ammonia can be stored and transported in tanks.”
Boost for Africa and Europe
How probable do you think it is that an enormous solar farm will actually be built in the Sahara?
“People are working very hard on European policy to make this possible. The Energy Commission of the European Union realizes that we can’t be self-sufficient in energy in Europe. We will have to rely on North Africa for large-scale green energy. If we manage to make agreements about joint development and exploitation with all the countries involved, we will also create opportunities for employment and prosperity in that area. It is conceivable, for example, that water will be needed to make hydrogen and that pipelines will be built to take water to the Sahara. A pipeline of that kind can obviously be used to take more water to the desert than is strictly necessary for the production of hydrogen. It would then be possible to use reverse osmosis to turn it into drinking water or even to grow food. You can also use the sand of the Sahara, or silicon, for the production of solar cells. From this point of view, it’s fair to say that sun, sea and sand are the building blocks of a fully circular system. And so the decision to install solar farms in the Sahara could trigger enormous levels of economic activity in Africa, and that could hopefully put a brake on migration flows to Europe. On top of all that, this approach could also deliver an economic boost for Europe because we not only have the knowledge required but also the facilities to produce the electrolysis systems required.”
What consequences could the transition to hydrogen have for global shipping?
“At the moment, we are still transporting shiploads of coal, oil and liquefied natural gas (LNG) all over the world and I expect a lot of those flows to be replaced by hydrogen. Either in tankers in liquid form or through gas pipelines. As I said, you can also transport hydrogen in liquid form after converting it into ammonia first. To make hydrogen gas liquid, you have to cool it to -253 degrees centigrade. The process is similar to the process used to make natural gas liquid (LNG). That always involves evaporation in a process known as boil-off. You can capture that vapor and use it to propel the ship, eliminating carbon emissions entirely. But hydrogen can also play an important role as an alternative fuel for other types of seagoing vessel.”
Even so, critics often point out that a lot of energy is lost in the production of liquid hydrogen…
“Once again, that’s right. But the question is: how much of a problem is that? You can only get a picture of the benefits of this transition by looking at the total system costs. You may need 20% more energy to liquefy hydrogen but you can easily solve that problem by installing more solar panels. If producing electricity doesn’t cost any more than 1.5 cents per kWh, the higher costs of the liquefaction process are negligible. One kilo of hydrogen is the equivalent of 39.4 kWh. So you have to generate 8 kWh extra to liquefy the hydrogen. That’s eight times 1.5 cents. In practice, the loss of this 20% leads to almost no serious increase in the cost. The total costs are still lower than other ways of generating, transporting and storing energy.”
Finally: you said earlier that hydrogen gas can be transported safely through pipelines without many modifications. Does that mean we can carry on using the existing natural gas pipelines as usual?
“Certainly. There has been a hydrogen pipeline between Rotterdam and northern France for thirty years now. That proves that hydrogen can be transported safely through a pipeline. The network of gas pipelines is well regulated in the Netherlands and other Western European countries, but there is still no legislation about the transport of hydrogen. Officially, it is not yet permitted in the Netherlands to transport hydrogen through our natural gas network. As we speak, people are working on making one of the large gas pipelines suitable for this purpose. Barring a few minor modifications, such as the use of a different type of compressor, using the existing natural gas infrastructure for hydrogen is straightforward.”