The world is moving with increasing urgency towards building highly efficient renewable energy systems. This is set to increase as countries, financial institutions, and investors put more funds behind renewable energy projects. Today, we are at a crucial inflection point where if we continue to step up our collective efforts, we can really accelerate the use of renewable energy to create green hydrogen at an unprecedented rate. The challenge is humongous: only 0.1 per cent of hydrogen produced today can be called green hydrogen.
However, considering the recent push towards green hydrogen by major global economies, including India and the UK, a new Frost & Sullivan study projects that global green hydrogen production will skyrocket at a compound annual growth rate (CAGR) of 57 per cent between 2019 and 2030, rising from 40,000 tons to 5.7 million tons. As we continue to install renewable energy systems to produce electricity, we have to overcome a few key challenges.
Renewable energy (solar and wind) is intermittent in nature, which means that since energy generation is dependent on the sun and the flow of the wind, the electricity output fluctuates, resulting in surges and dips in flow of power to the grid. The solution to this ebb and flow in the output of renewable-based electricity generation is to use large storage systems. Today, most electricity generators use large batteries to store excess renewable energy for later use. However, this is only cost-effective if energy is stored for a small duration. For longer periods, battery costs rise exponentially, making the entire process expensive and raising per unit generation cost. This is where hydrogen can have an impact.
Hydrogen produced by renewable energy driven electrolysis can be used to store excess renewable energy for longer periods, considering that hydrogen energy provides high energy density, low capital cost, and easy integration with the existing energy network. Interestingly, hydrogen can also be used to fuel cars, buses, trucks, and even aeroplanes. In fact, Juniper Research has found that the number of hydrogen vehicles in service globally will exceed 1 million in 2027, from just over 60,000 in 2022 – a substantial growth of over 1,500 per cent.
Apart from transport, green hydrogen has the potential to decarbonise the steel industry. Today, steelmaking contributes to about 8 per cent of global carbon emissions and is under huge pressure to cut down on its excessive contribution to global warming. Hydrogen can replace coal, currently used in the process to make steel, potentially greening the entire process. Though this will drive the price of steel by up to a third, the gap is likely to narrow and could disappear by 2030.
Additionally, hydrogen can be used in the process of heating homes domestically, in the natural gas industry, and even in ammonia production. Natural gas could be replaced with hydrogen as a low-emission fuel for heating, electricity, and transportation. It can also be utilised as an affordable feedstock for the production of ammonia, chemicals, petrochemicals, synthetic fuels, glass, and metal.
One of the most promising benefits of hydrogen, which has the potential to revolutionise travel systems, is its use as an alternate fuel. Hydrogen, in the past, has been used to power airships, space shuttles, cars, buses, and even submarines. Today, fuel cell technology (powered by hydrogen) makes for a promising alternative to gasoline-based engines across the world. A fuel cell consists of two electrodes – a negative electrode (or anode) and a positive electrode (or cathode) – sandwiched around an electrolyte. A fuel is fed to the anode, and the air to the cathode. In a hydrogen fuel cell, a catalyst at the anode separates hydrogen molecules into protons and electrons, which take different paths to the cathode. The electrons go through an external circuit, creating a flow of electricity. The result? A car running completely on green hydrogen and water vapour as its only exhaust.
A pertinent question arises here. Why even use a hydrogen-based fuel cell when electric cars are successfully running all over the world? Simply because hydrogen has an energy-to-weight ratio that is ten times greater than lithium-ion batteries, which means it can power a car for longer distances as compared to a battery-powered cell. Secondly, while it may take 45 minutes to an hour to recharge a battery, hydrogen can be simply refuelled in a car’s tank in about 5 minutes. Now a pertinent question arises: if hydrogen is that efficient, why is it that we still see a lot of battery-powered vehicles and only a handful of hydrogen ones on the roads? One big reason is that fuel cell technology is still quite expensive. Hydrogen in itself is still quite an expensive fuel compared to other available options.
Second, platinum, an element used as a catalyst in the fuel cell, still comes at an extremely high price. Third, moving hydrogen from one place to another is still a challenge, and while required infrastructure is being developed, it will take time to offset the costs associated to make hydrogen a viable fuel. An alternative here is ammonia, which seems to be one of the most promising hydrogen carriers among all available methods. The advantage of ammonia in carrying hydrogen per unit volume is great when compared to modern hydrogen storage methods, such as metal hydrides, which store H2 up to 25 kg/m3 or to liquefied hydrogen (1.5 times lower). This often translates into ammonia offering a cheaper cost per unit of stored energy than hydrogen, as computed. Additionally, ammonia can be used as a profitable energy carrier for hydrogen-distributed generation using compact ammonia decomposition reactors.
Fourth, at the end of 2021, just about 700 hydrogen refuelling stations were operational worldwide while battery-powered EV charging stations crossed the 1 million mark in 2020 itself. While hydrogen has the potential to take over the electric vehicles market completely, it might take time to bring down the costs and additionally set up the required infrastructure. In the future, hydrogen may be used to power long-haul trucks and even aircraft, considering its advantage as a long-range energy provider. In fact, Airbus is already developing a hydrogen-powered aircraft and has even signed MoUs to develop hydrogen infrastructure at airports.
Excerpted with permission from Fossil Free: Reimagining Clean Energy in a Carbon-Constrained World, Sumant Sinha, HarperCollins India.