The long road to green hydrogen
10,000 wind turbines for the steel industry alone
By 2050, not only mobility should function in a CO2-neutral way, but our entire industrial society. Electricity generated from renewable sources, for example, will allow battery-electric cars to run on a CO2-neutral basis. Even if all cars in Germany were to run on electricity in 2040, for example, only about 25 percent more electricity would be needed than today.
With hydrogen and fuel cell drives, CO2-neutral operation would also work in principle if the hydrogen itself were produced by electrolysis from renewable electricity. But this is exactly where the problem lies: “Due to the poor efficiency chain, starting from the off-shore wind farm to the electric motor in the car, including liquid distribution and high-pressure refueling, the demand for primary energy for the production of hydrogen for fuel cells in passenger cars is about five to six times higher than for battery vehicles,” writes for example our podcast guest Prof. Martin Doppelbauer in his strategy paper. This means that the electricity required to run all 47 million passenger cars in Germany on hydrogen would be about 1.5 times greater than the total electricity produced today. That can’t work, especially since in the future not only about 50, but 100 percent of the electricity will have to come from renewable sources.
What we need hydrogen for
But energy transmission or storage doesn’t work purely electrically everywhere. Aircraft, for example, cannot carry as many batteries as they need. Hydrogen fuels could be the alternative. Hydrogen offers a much higher energy density. One kilogram of hydrogen contains almost as much energy as three kilograms of gasoline, and one liter of Super carries almost nine kWh of energy. The 700-kilogram battery of an Audi E-Tron is therefore roughly equivalent to a tank of ten liters of gasoline. After all, the efficiency of the e-car is three times as high as that of the combustion engine, so in this respect the E-Tron still has about 30 liters of gasoline in its tank.
However, the calculation also shows that if you have to take a lot of energy with you, you need a carrier other than batteries, and hydrogen can basically be produced with (green) electricity, the energy of which is then stored in it. Taking hydrogen with you, however, is not trivial. At normal temperatures and atmospheric pressure, one kilogram of hydrogen occupies more than eleven cubic meters of volume – hence its use in e-fuels.
But even for stationary processes, hydrogen is a decarbonization option. For example, for steel production, where enormously high temperatures and thus large amounts of energy are required. Currently, steel production mainly uses coke (coal). In Germany, it emits around 70 million tons of CO2 (equivalent) per year. An alternative to the common iron ore reduction in the blast furnace using carbon is the direct reduction of iron ore using hydrogen. Complete substitution of coal or coke would create an additional hydrogen demand of 2.4 million tons per year in Germany. The German Energy Agency believes that “today’s hydrogen demand and that needed for direct reduction in the future can be successively covered by green hydrogen.”
How is hydrogen produced?
Industry already produces large quantities of hydrogen for fertilizer production and for refineries. There, it is needed as an auxiliary material for the production of gasoline and diesel. In 2019, according to Statista, there were a total of about 117 million metric tons of hydrogen worldwide. 69 million metric tons were created from natural gas, and the remaining 48 megatons as a byproduct of chemical processes.
Gray hydrogen is anything but EO2-neutral
However, steam reforming of hydrogen from natural gas produces ten tons of CO2 per ton of hydrogen (about 400 grams per kWh of H2, according to one study). This hydrogen is therefore called gray. It is of no use for CO2 neutrality in the future. Unless the CO2 produced during steam reforming is separated and stored, pressed underground, for example in former gas deposits. The hydrogen is then called blue – because some residual CO2 emissions always remain, it is not green. What’s more, natural gas as a feedstock already has significant emissions attached to it through extraction, processing and transportation. “These upstream emissions account for about 25% of the total emissions from natural gas,” according to an evaluation of several studies (p. 8 there). Currently, blue hydrogen is considerably cheaper (by a factor of about three) than green hydrogen, which is why it has good chances, especially as a transitional solution, despite the higher CO2 emissions and the limited deposits of CO2. Price forecasts vary between 20 and 60 percent additional costs for green hydrogen in 2030.
On the other hand, estimates for 2030 assume a hydrogen demand for steel production of three million tons; this would be equivalent to 150 TWh of electrical energy. This corresponds to the annual output of 3333 MHI Vestas V164 offshore wind turbines. Currently, there are only 1200 offshore wind turbines in the German North and Baltic Seas. Onshore, there are almost 29,000, the most powerful of which, the Nordex N149, produces only a third of the yield of the offshore Vesta. Accordingly, the 150 TWh would require 9740 such wind turbines on land. Nevertheless, it might make sense to produce the electricity for hydrogen generation on land. At the very least, it would be advantageous if the electrolysis took place where the steel is produced. Then one would save the transport of the light and volatile gas – which brings us to the next point.
Steel production with green hydrogen in direct reduction plants is CO2-neutral. Until sufficient climate-neutral hydrogen is available, the use of natural gas in direct reduction plants can already significantly reduce emissions compared with the coal-based blast furnace method. Thyssenkrupp Steel, for example, plans to start up the first large-scale direct reduction plant in 2024. The more green hydrogen – Thyssen reckons it will need 700,000 tons or 3,000 wind turbines in the long term – available by then, the greener the steel.
Solar power from the desert – hydrogen too?
No wonder, then, that scenarios for hydrogen production are also developing elsewhere, where there is space for wind turbines or solar plants, land is correspondingly cheap, and the cost of regenerative energy production is correspondingly lower. In the Sahara, for example. One such idea is already a good ten years old: “Desertec” proposed solar power plants in the Sahara and overland pipelines to Europe. A new position paper takes up the idea again. Instead of expensive power lines, the idea is now to use electricity to produce hydrogen.
However, electrolysis requires a lot of water – ten liters per kilogram of hydrogen. Water and sunny deserts are largely mutually exclusive. That’s why Desertec proposes installing seawater desalination plants, of course also powered by wind and solar energy. Even under the most unfavorable conditions, the cost share for this should not exceed 2 percent of the total costs; any surplus production could help local irrigation projects.