Future of Renewables: Green Hydrogen
H2O + Green Energy = H2 + O2
“I believe that water will one day be employed as fuel, that hydrogen and oxygen which constitute it, used singly or together, will furnish an inexhaustible source of heat and light, of an intensity of which coal is not capable.” — Jules Verne (1874)
The passage above written by the late French novelist Jules Verne appeared in his 1874 book “The Mysterious Island”. It goes on to predict that the coalrooms of steamers and the tenders of locomotives will one day be stored with hydrogen and oxygen and that water will become the coal of the future.
What a beautiful prediction it came out to be.
Hydrogen is indeed becoming a fuel of the present (rather than the future). While its current uses are mainly for petroleum refining and fertilizer production, its nature as an energy carrier makes it feasible for use in transportation and utilities too.
What does this then have to do with “green”?
To answer that, it is important to understand that hydrogen production is not a new activity to mankind and it has been produced and used commercially for more than a century now. One of the earliest usage of hydrogen for transportation purposes was the famous Zeppelin airship, designed by Count Ferdinand von Zeppelin and used for thousands of commercial flights in the early 20th century.
The main issue is that hydrogen is typically produced from fossil fuels. In fact, according to the International Renewable Energy Agency (IRENA), an estimated 95% of today’s worldwide hydrogen production comes from fossil fuels. Producing hydrogen using fossil fuels has the unfortunate effect of emitting significant amounts of carbon dioxide, inadvertently contributing to the acceleration of global warming and climate change.
What is Green Hydrogen?
Green hydrogen involves producing hydrogen via electrolysis, with the electricity supplied by renewable or zero-carbon sources. This differs from other types of hydrogen which are produced either via different production pathways or by a different type of energy source.
Blue hydrogen is produced via reforming of natural gas or gasification of biomass or organic waste, coupled with carbon capture and storage (CCS) of the CO2 waste product stream
Grey hydrogen is produced in a similar manner to blue hydrogen but there is no carbon capture process and CO2 is emitted into the atmosphere.
There are also other colours that might be referred to such as pink (electrolysis using nuclear power), yellow (electrolysis using solar power) and turquoise (methane pyrolysis with a solid carbon by-product)
What Can It Be Used For?
Major industrial applications today involves using hydrogen in chemicals (in the form of ammonia and methanol), oil refineries and manufacturing of iron/steel.
However, the value of hydrogen lies in its property as an energy vector. This means that it allows for energy to be available for use at a time and distance away from a source.
Not too complicated I hope?
An example of using hydrogen as an energy vector is the fuel cell. Hydrogen fuel cells can power electric vehicles and help to drastically reduce air pollution as they have zero tailpipe emissions.
Other applications of hydrogen as a energy vector includes hydrogen-based fuels for maritime and transportation, heating of buildings (by blending hydrogen in existing gas networks) and can even be used for seasonal storage of electricity to provide flexible and back-up power generation for countries with high levels of renewable capacity.
With so many potential applications and expanding usage of hydrogen, it is important to ensure the value chain for producing and using hydrogen is entirely “clean” from start to end, hence the need to focus on green hydrogen and move away from grey/blue hydrogen as much as possible.
Key Enablers to Grow the Green Hydrogen Sector
Lowering Costs of Production
There are two main methods of electrolysis to form green hydrogen: Alkaline and Polymer Electrolyte Membrane (“PEM”).
While using electrolysis to form green hydrogen is still at early stage commercial development, standardizing manufacturing and design of electrolysers as well as improving system efficiencies will allow for huge cost reductions per kg of hydrogen produced.
Another factor that can help reduce cost is to avoid the use of rare and scarce materials such as iridium and platinum which can be expensive and only available in limited quantities. Alkaline electrolyers do not use these materials, making it a good candidate for scaling up.
Estimates today from IRENA predicts that green hydrogen costs are expected to become competitive with that of grey/blue hydrogen from 2035 onwards. This could be even sooner for locations with extremely low cost of renewable energy (eg. Chile, Middle East)
Lower Costs of Transportation and Storage
The transportation and storage costs of hydrogen has an impact on its overall cost as well as competitiveness against other fuels. The state and medium in which hydrogen is transported in plays a huge part in determining the costs of transportation.
Hydrogen is a gas at normal temperatures but liquefies at below -253 degrees celsius. Liquefaction of hydrogen is an important step as liquefied hydrogen occupies a smaller volume for storage and transport vs compressed hydrogen.
The only hitch is that the liquefaction process attracts a larger energy penalty as it is a more energy intensive process than simple compression. With today’s technology, the power consumption (10kWh/kg) needed to liquefy 1kg of hydrogen is equivalent to around 30% of the useable energy contained in 1kg of hydrogen (33kWh/kg). For compression, this figure is around 10-15%.
One will need to consider the cost vs benefits of transporting hydrogen in liquefied or compressed forms.
There are also alternative ways of transporting hydrogen, such as in the form of ammonia, depending on the end use of the hydrogen.
Additionally, lowering costs of transport will help the development of an export industry, further allowing any supplier to access the global market.
Government Policies
Government policies to drive the growth of green hydrogen are crucial to ensure the green hydrogen sector fulfils its immense potential and contribute to the fight against climate change.
If we go back 10 years in the past, strong support by the government was important to the eventual accelerated deployment of solar and wind generation to achieve its current scale today.
Several of the G20 countries (such Australia, Japan and France) have already announced their hydrogen roadmap for the future and incorporated elements relating to the proliferation of green hydrogen.
Great Times Ahead for Green Hydrogen
The advent of low-cost green hydrogen is expected to rewrite the energy landscape completely and will become commonplace in all our lives, displacing many of the fuels and energy sources that we know today.
I look forward to seeing the amazing growth of this sector over the next few decades.
This article is part of a series on the future of renewable energy. If you are interested in finding out more, do feel free to check out the other articles in the series.
