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Hydrogen Applications


Green hydrogen in the energy sector

Like many other renewable applications, H2 interest rose in the 1970s with the oil crises’. Since then, the automotive industry took the lead in demonstrating the ample potential of this technology. But after the oil prices (and hence natural gas and gasoline prices) stabilized, the interest lost momentum, and it wasn’t until the 2000s when a combination of a refreshed view on climate change, along with an increase in oil prices, and the advent of electrical cars (which proved that there are feasible alternatives available) that reignited the focus on H2 applied for energy purposes.
When we talk about the use of hydrogen in energy, there are two main ways in which it can be used to generate electricity:

Combustion Source: Siemens SGT - 400



The first and most popular way is through its combustion, a process that has a number of characteristics. The main advantage of burning hydrogen to generate electricity is its high calorific value, which makes the efficiency of the hydrogen plant significantly higher than other alternatives.

The combustion of H2 does not emit carbon dioxide, it is not a poisonous gas and there is no danger of poisoning in the presence of a leak in the system. The main disadvantages are several, the most important of which is the presence of increased levels of nitrogen oxides in the combustion of hydrogen, which is due to the rapid combustion of hydrogen and the high temperatures at which it burns. Another disadvantage of burning hydrogen for electricity generation is the additional safety measures that must be taken, as it is a highly flammable gas.

The most significant hurdle today for the commercial combustion of hydrogen for electricity is related to its physicochemical properties, which does not allow a 100% use in the current gas power plants, which leads to the need to develop a new type of turbine that will fully absorb hydrogen as a raw material. For turbines used in current gas-fired power plants, it is possible to blend hydrogen with natural gas in small quantities of 5 to 20% without the need for any change in the production process.

We must also consider hydrogen-based fuels and feedstocks (such as synthetic methane, synthetic liquid-fuels, ammonia or methanol), which are those resulting energy carriers that can be produced from H2. An interesting point is that except for ammonia, the other 3 require carbon (C) for its production, meaning these can also be integrated in a wider process that includes carbon capture and storage (CCUS), proving once again that H2 has an immense an ample potential across industries. These types of fuels have the added advantage of having a higher energy density, so they are easier to store, transport and use, some of pure H2 drawbacks. And not only this, but existing infrastructure already processes them for ongoing operations or require less capital intensive investments to do so. They can be consider as stepping stones towards the widespread use of H2.

Fuel Cells Source: South Korea 50 MW fuel cell plant

Fuel Cells


The second way to produce electricity from hydrogen is through an electrochemical process in which O2 is added to H2 in fuel cell membranes. An electrochemical process takes place in them and the only "waste" product is water (H2O). There are many types of fuel cells -just like for electrolyzers-, the most popular being alkaline fuel cells followed by proton exchange membrane (PEM) fuel cells, as well as several other types that have not been developed for commercial purposes.

Generating electricity with fuel cells is an entirely GHG emission-free process, (always considering that the hydrogen used is of proven green origin) and doesn’t produce either particulates, sulfur oxides, nitrogen oxides nor it raises ground-level ozone nor produce. Apart from zero-emission, generating electricity with fuel cells has other important advantages. One of them is the flexibility of this type of system. Unlike large power plants, fuel cells can start and stop production in a few seconds, making them flexible and key for balancing the power grid. Fuel cells for large-scale production facilities are often housed in modular containers, making their installation possible within a few days, as well as increasing the capacity of the installation proportionally. Globally as of 2021, there is over 800 MW of installed capacity for electricity generation, the largest plant with a capacity of 50MW is located in South Korea. Read more here

The biggest downside of this particular application lies in the low-efficiency factor when the whole value chain is considered. After converting electricity to hydrogen, shipping and storing, then converting it back to electricity in a fuel cell; the delivered energy can be below 30% of what was in the initial electricity input. When put in perspective, an internal combustion engine has on average a 20% efficiency rate and a state-of-the-art coal-fired plant 45% efficiency rate (up to 60% in the case of combined cycles).

Currently, the best use for fuel cells as electricity producers is for off-grid sites. Nowadays, backup power is provided by diesel generators (which deteriorates air quality and could be imported -H2 can be produced virtually anywhere-). The mobile telecommunications industry relies on an uninterrupted supply of services from its 7 million bases distributed worldwide, fuel cells offer a very attractive replacement for diesel, being able to operate in environments of up to -50 ° C.