Breathing Underwater

When I was building the domed city of Aquataine, one of the first things I researched was, “How will these people breathe underwater?” It doesn’t matter whether you are onboard a space station, or in a submarine, or in a city underwater, there are three things you have to do—make oxygen to replace what all the people use up as they breathe, remove the carbon dioxide so it doesn’t kill all the breathing people, and remove the moisture caused by exhaling and prevent that water from building up on everything in sight. I found a few sites describing these processes and how they are used on a submarine, so that formed the basis of these critical systems in my city.

First, there’s the oxygen generation. The best way for Aquataine to get oxygen is to use sea water. They’d first distill it to remove impurities like salt. The sea water would be heated, which would create water vapor, which would rise leaving the salts to settle. The vapor would then be cooled, and condensed into a collection tank. Electricity would be applied to the purified water by a process known as electrolysis, which would cause the molecules to separate into hydrogen and oxygen. During electrolysis, the negatively charged oxygen molecules can be captured and stored or vented directly into the dome’s ventilation systems.

Each dome has several air outlets which function like the ductwork in our homes.  In mention this near the end of my book UNDERCURRENT, on page 323. “The positioning of the fresh air outlets helps to spread the sweet scents from the plaza’s large beds of Dianthus and Lavender—Aunt Lori’s favorites—throughout the dome.”

Also in UNDERCURRENT, Phelan Maxwell spends the night outside the oxygen generation plant while he’s on the run, investigating Saxon Cole. When it gets late and people take their body heat inside their homes, it can get quite chilly in the domes. Phelan stays too late in the Commercial Dome (one of the smaller domes that surround Aquataine’s huge Central Dome), and decides to spend the night while he investigates the Wave party’s headquarters. He finds an out of the way spot just inside the oxygen generation plant, where I suspected a good bit of heat would be generated by the distillation and electrolysis processes.  

The second thing we have to do is remove the carbon dioxide from the air. Carbon dioxide is toxic if concentrated in the air we breathe. To remove it, we need something called a “scrubber,” which uses soda lime ( a mixture of sodium hydroxide and calcium hydroxide) to trap the carbon dioxide by a chemical reaction, removing it from the air.

Third, we need to remove the moisture in the air using a dehumidifier. The captured moisture can be used to feed right back into the oxygen generation system, or it can be used elsewhere in the dome for drinking, bathing, watering plants, or filling water balloons. On a submarine, dehumidification is very important, because moisture cannot be allowed to cover the walls of the sub or coat instruments or make floors slippery. I was concerned that the moisture would accumulate on the photonic lighting panels that line the dome.

In the dome, I wondered if there could be some clever use of this surplus water. Could it be collected and used to provide a rain shower once in a while? Could this water be used for fountains, or ponds, or something to provide for a more natural setting? In the end, I thought space would be at a premium, and opted against this. But, the photonic lighting panels give the illusion of a sky, and they tend to get dirty. I decided to use a cleaning process (okay, it’s just power washing) for the panels, which every now and then will give the residents a little rain shower. The mist in the air with the light of the panels even provides a rainbow effect, brightening the day of each of our city’s residents.

For all you “Surfs” out there—what my native dome residents call the people who move to the domes from the surface—would you move from your home to an underwater city?

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