Renewable energies are not sufficient to ensure decarbonization
Renewable energies alone are not sufficient to ensure complete decarbonization of the industry. While they can contribute to the electricity sector when there is wind or sunshine, what comes into play when these conditions are not met? In such cases, a storage and energy management system is necessary, beyond batteries, and in this context, green hydrogen plays a relevant role.
Hydrogen technologies can help provide flexibility mechanisms to the electrical grid, which is becoming increasingly necessary due to the electrification of certain sectors and the growing penetration of renewable generation in the system. When these technologies are properly implemented, they can help reduce energy costs, harmful emissions, and provide supply security.
What is green hydrogen and how is it obtained?
Hydrogen is the most abundant chemical element on the planet and is found in water and organic matter. The advancement of renewable energies allows us to generate hydrogen from clean energy sources, known as green hydrogen. That’s why to produce it, only water and electricity from renewable sources are needed through a process called electrolysis or through organic matter transformation processes.
Hydrogen as an energy storage source
There are various ways to store hydrogen, but the most commonly used method currently is high-pressure tanks ranging from 350 to 700 bars. Its use is safe thanks to advances in material technology in recent years, and it allows for the storage of large amounts of energy for extended periods of time, enabling effective management of the electrical grid.
Another method is by cooling the gas using a cryogenic refrigeration system, although this approach poses certain challenges. Apart from requiring a tank to store the hydrogen, continuous cooling systems are necessary to prevent losses. For large-scale storage, it is possible to store hydrogen in salt mines or former natural gas fields.
- The resulting energy is clean.
- Hydrogen has a high energy density per weight.
- Easy storage for extended periods of time.
- Possible efficiency loss due to double conversion: electrical energy needs to be converted into hydrogen through an electrolyzer and then converted back to electricity using a fuel cell.
- Technical expertise is required for storage procedures.
Power to gas
The concept of power to gas refers to the conversion of electricity into thermal energy in the form of gas. This gas can be hydrogen or synthetic natural gas, which, through its transformation from hydrogen, can be stored and introduced into the gas grid as needed.
The applications currently available in the market include natural gas turbines for combined cycles, cogeneration systems, and sector coupling, which involves interconnecting the electricity grid and the gas grid. Currently, it is estimated that there is 5% hydrogen in the gas grid, and it is projected to potentially reach up to 20%.
- Natural gas turbines operate at 100% efficiency.
- Replacing the entire gas grid is neither an easy nor a cheap task.
The aim is to explore new avenues to replace natural gas with hydrogen. Homes could receive hydrogen through existing gas pipelines, and we could heat our houses using boilers fueled by this green fuel.
- It is a technology that we are all familiar with.
- There are no concerns about harmful leaks inside the house.
- Replacing the entire boiler network takes time and investment.
- Technical knowledge is required for its use.
A fuel cell is an electrochemical device that directly converts chemical energy into electrical energy. It uses a fuel (usually hydrogen) and an oxidizing agent (often oxygen) to produce water, electricity in the form of direct current, and heat.
- The refueling system is faster than that of batteries.
- It is much more efficient than systems that rely on traditional fuels.
- Lower efficiency compared to batteries.
- Shorter lifespan than batteries.
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