Green hydrogen production

The role of cooling in production of Green Hydrogen

Green hydrogen is hydrogen produced from renewable sources of energy (wind, solar, hydropower) via electrolysis. The electrolysis process splits water molecules in hydrogen (H2) and oxygen (O2) as electricity passes through the water. The major advantage of this process is that there is no CO2 emission, therefore green hydrogen contributes to the reduction of global carbon emissions as opposed to hydrogen produced from non-renewable resources like natural gas.

The electrolysis process requires a significant amount of energy. A part of this energy is lost as heat. The amount of heat released can vary depending on the electrolyzer design. The capacity of an electrolyzer is expressed in MWe (megawatts of electricity input). During the electrolysis process, the heat losses will be approx. 25% to 35% of the electricity input and this heat will need to be rejected to keep the stack within a desired temperature range.

As an example, a 100MW(e) electrolyzer, releases approx. 30 MW heat and therefore the same amount of cooling will be required. Further downstream, there is also heat rejection required for the compression of the produced hydrogen. Electrolyzer and compressors can be cooled separately for small installations while for large scale installations, cooling can be combined via a central cooling system.

BAC's cooling solutions

We have a very extensive cooling product range. From evaporative open and closed circuit cooling towers, hybrid, adiabatic and dry cooling systems, whatever the application or the challenge, we have the knowledge in house to select the best product that meets your cooling needs.
The most suitable cooling technology is often determined by the project location and the availability and cost of water and/or electricity.

Open cooling towers

One way to provide the cooling is by means of an evaporative open cooling tower. Warm process water enters at the top of the cooling tower, flows over a heat transfer media (fill) and gets in contact with cold air. A part of the process water evaporates which removes the heat from the water. Cooling towers have multiple advantages over other cooling technologies:

• Extremely energy efficient,
• Compact footprint
• Lowest process temperatures because they can achieve a low approach (2-4°C).

Closed circuit cooling towers

If you want to isolate the process fluid from the outside air, you can use a closed circuit cooling tower. In this case there is no contact between the air and fluid being cooled. There are 2 separate circuits: the hot process fluid flows through a coil bundle and a second spray water system wets the coil bundle. The process water that flows through the coil stays clean and free from contamination. Benefits are:

• Smaller volume of spray water to treat less maintenance is required.
• No contamination of the process fluid

The coil bundle makes however this type of unit more expensive than an open cooling tower.

TrilliumSeries adiabatic coolers

If there is not enough water available at the site location, adiabatic cooling can be the optimal solution. An adiabatic coolers is a dry cooler equipped with an adiabatic pre-cooler section. Before the air is drawn through the high density finned coil, it is pre-cooled adiabatically as it passes through an adiabatic pad where water is evaporated in the air. The air that enters the adiabatic pad is cooled to a depressed dry bulb temperature which is almost the wet bulb temperature. The dry finned coil will see cooler air which results in lower process temperatures. This type of coolers uses only water for a short amount of time during the year and is preferably used in regions with a low relative humidity. Benefits are:

• +/-90-95% water savings compared to an evaporative cooler.
• no water treatment

TrilliumSeries dry coolers

The TrillumSeries TDFS double stack dry cooler has been developed to achieve maximum capacity in a small footprint, all with low sound and energy consumption. Benefits are:

• Superb thermal capacity - Best in class heat rejection due to fan and double stack coil design; Multiple coil circuiting to minimize pumping energy costs
• Low sound - Quiet unit operation; Night Quiet operation mode; Optional Whisper Quiet fans reduce sound power by up to 13 dB.
• Easy maintenance - All critical components are easily accessible from internal and external access platforms; motor removal system
• Low installed cost - Fewer total units means less steel support, field piping and wiring; All coil connections are located on same end; Sections are optimized for efficient truck shipping.
• Redundancy - 4 fans with individual fan motors; the fans remain operational even in the event of loss of PLC signal