A completely clean, renewable energy system that can be produced locally and that can easily power heat, energy storage and transportation, and travel — that's the future that promoters of a hydrogen economy envisage.
If it sounds a bit like rocket science, that's because it is. Hydrogen is what's used to fuel rockets — that’s how powerful it is. In fact, it’s three times more powerful as a fuel than gas or other fossil-based sources. And, after use, it’s frequently converted to drinking water for astronauts.
US President Joe Biden has highlighted the potential of hydrogen in his ambitious plans for economic and climate recovery and a number of recent reports have been encouraging about hydrogen’s breakthrough moment, including McKinsey and Company (Road Map to a US Hydrogen Economy, 2020) and the International Energy Agency.
Hydrogen fuel cells provide a tantalising glimpse into our low-carbon future
The McKinsey report claims that, by 2030, the hydrogen sector could generate 700,000 jobs and $140bn in revenue, growing to 3.4 million jobs and $750bn by 2050. It also believes it could account for a 16% reduction in CO2 emissions, a 36% reduction in NOx emissions, and supply 14% of US energy demand.
So how does it work?
Simply put, hydrogen fuel cells combine hydrogen and oxygen atoms to produce electricity. The hydrogen reacts with oxygen across an electrochemical cell and produces electricity, water, and heat.
This is what gets supporters so excited. In theory, hydrogen is a limitless, incredibly powerful fuel source with no direct emissions of pollutants or greenhouse gases.
So what's the problem?
Right now, there are actually a few problems. The process relies on electrolysis and steam reforming, which are extremely expensive. The IEA estimates that to produce all of today’s dedicated hydrogen output from electricity would require 3,600TWh, more than the total annual electricity generation of the European Union.
Moreover, almost 95% of hydrogen currently is produced using fossil fuels such as methane, natural gas, or coal (this is called "grey hydrogen"). Its production is responsible for annual CO2 emissions equivalent to those of Indonesia and the United Kingdom combined. In addition, its low density makes it difficult to store and transport — it must be under high pressure at all times. It’s also well-known for being highly flammable — its use as a fuel has come a long way since the Hindenburg Disaster but the association still makes many people nervous.
A Hydrogen refuelling station Hafencity in Hamburg, Germany. Infrastructure issues must be addressed if we are to see more hydrogen-fuelled vehicles on our roads. | Image credit: fritschk / Shutterstock.com
So there are quite a few problems. What’s the good news?
In the last few years, we've seen how rapidly investment, innovation, and infrastructure policy can completely transform individual renewable energy industries. For example, the IEA analysis believes the declining costs of renewables and the scaling up of hydrogen production could reduce the cost of producing hydrogen from renewable electricity 30% by 2030.
Some of the issues around expense could be resolved by mass manufacture of fuel cells, refuelling equipment, and electrolysers (which produce hydrogen from electricity and water), made more likely by the increased interest and urgency. Those same driving forces could improve infrastructural issues such as refuelling stations for private and commercial vehicles, although this is likely to require coordination between various stakeholders, including national and local governments, industry, and investors.
The significant gains in renewable energy mean that “green” hydrogen, where renewable electricity powers the electrolysis process, is within sight.
The IEA report makes clear that international co-operation is “vital” to progress quickly and successfully with hydrogen energy. R&D requires support, as do first movers in mitigating risks. Standards need to be harmonised, good practice shared, and existing international infrastructure built on (especially existing gas infrastructure).
If hydrogen can be as efficient and powerful a contributor to a green global energy mix as its proponents believe, then it's better to invest sooner rather than later. If that investment can help power a post-Covid economic recovery, even better.
2019 has been declared by UNESCO as the Year of the Periodic Table. To celebrate, we are releasing a series of blogs about our favourite elements and their importance to the chemical industry. Today’s blog is about the first element in the periodic table, hydrogen!
Hydrogen isn’t just for keeping balloons afloat. Image: Pixabay
Hydrogen (H2) gas has many uses in modern engineering. Scientists are always searching for cheaper, more renewable fuel sources that have a lower negative impact on the environment. Hydrogen was frequently used to generate energy in the past, and this drive for more renewable energy has given hydrogen-derived fuel a new lease of life.
Hydrogen can be used in fuel cells. These act like batteries, generating their energy from a reaction between hydrogen and oxygen (O2). Hydrogen fuel cells have been incorporated into many modern technologies, including automotive. As the reaction occurring only generates heat, electricity and water, fuel cells are significantly better for the environment than many alternatives. Hydrogen is also much cheaper as a commodity that typical fuels.
Hydrogen fuel cells can now be used to power automotive vehicles, including cars!
Engineering cooling systems can use hydrogen. The gases physical properties make it 7-10 times better at cooling than air. It can also be easily detected by sensors. Because of this, hydrogen is used in cooling systems, which are generally smaller and less expensive than other available options.
Hydrogen gas can be used in reactions. The most famous reaction using hydrogen is the production of ammonia (NH3), also known as the Haber process. The Haber process was developed by Fritz Haber and Car Bosch in the early 20th century to fill the need to produce nitrogen-based fertilisers. In the Haber process, atmospheric nitrogen (N2) is reacted with H2 and a metal catalyst to produce NH3.
Nitrogen-based fertilisers are still used today, but ammonia was one of the first to be commercially produced.
Ammonia is a valuable fertilised, providing much needed nitrogen to plants. It was used on a variety of agricultural plants, including food crops wheat and maize, in the 19th and early 20th century.
Chemists undertake other chemical reactions, such as hydrogenation and reduction, that utilise hydrogen, to make commercially valuable products. Some physical properties of hydrogen make it tricky, and often dangerous, to use in industry. However, careful control of conditions allow for its safe use on larger scales.
Hydrogen gas can be explosive, making it often dangerous to use.
Producing hydrogen gas
There are many ways to produce gaseous hydrogen. The four main sources of commercially produced hydrogen are natural gas, oil, coal and electrolysis. To obtain gaseous hydrogen, the fossil fuels are ‘steam reformed’, a process which involves a reaction with steam at high pressure and temperature.
Electrolysis of water is another method that is used in hydrogen production. This method is 70-80% efficient. However, it often requires large amounts of energy, specifically in the form of heat. This heat can be sourced from waste heat produced by industrial plants.
So, whats all this hot air about hydrogen? Source: Tedx Talks
An alternative method for producing hydrogen is via biohydrogen. Hydrogen gas can be produced by certain types of algae. This process involves fermentation of glucose. Some hydrogen is also produced in a form of photosynthesis by cyanobacteria. This process can be used on an industrial scale.
Overall, hydrogen technology, whether it be new developments, such as hydrogen fueled cars, or old, like the Haber process, remains critical to the chemical industry.