First, let me say what the theme of this book is not. You may have encountered the idea before that we don’t need to worry about solving environmental problems on Earth because we can always colonize Mars. The author, Marshall T. Savage, explicitly says that this is not the type of argument he is advocating.

“Our future lies in space, but the Earth is the womb of life, and it will be a long time before we can cut the umbilical cord. The new worlds we wish to create can survive their infancy only if the Mother of Life (Gaia) is here to nourish them. If we are to fulfill our Cosmic destiny as the harbingers of Life, we must first insure survival of the home planet.”

Savage then goes on to provide a concise description of the problems and their solutions. He explains that the primary things that support the human population on Earth are food and energy. These things must come from somewhere, but he notes that if we continue to overexploit the Earth to obtain them, then we will destroy our own living habitat. The solution is to find some source outside the biosphere. So far, these are obvious and familiar arguments, but it is necessary to begin with them in order to build the chain of reasoning. The interesting argument comes next. It is necessary in the interim, he says – in the interim before we begin to colonize space, that is – to find the resources we need from somewhere that is on Earth but that is not a part of the existing biosphere. This point could be argued with semantic hair-splitting, so let me clarify. We need a source of food and energy that will not bring about the poisoning or destruction of the Earth’s existing ecosystems into which we have so far been plugged in our known human history. That is still not a perfect way of putting it, but please reserve your arguments until you read on to learn more specific and concrete details of the plan that Savage is proposing.

You have probably figured out by now that he is saying we could and should get what we need from the ocean. You have probably heard this before. But did you know that there is enough latent energy in the oceans to supply the entire world power demand for 25,000 years? Did you know that the oceans contain 36 times more nitrates than the amount of nitrogen that exists in the Earth’s entire biomass? Did you know that it would possible to use sea colonies to act as carbon dioxide sponges and offset global warming, while still getting food and energy from them? Did you know that the open oceans are mostly lifeless, due to a lack of nutrients? Therefore, if human beings were to form marine colonies on the open oceans, we would not disturb or displace any existing ecosystems.

I’ll sketch a brief outline of how this would all work. There would be an ocean thermal energy converter in each sea city. It would work simply by extracting energy from the temperature difference between the warm surface waters of the equator and the cold deep waters. OTECs would produce more energy than they consume, on net balance. Savage says that for every 700 calories of energy they consumed, they would generate 1000 calories. Some of the net power surplus would be consumed by the colonies. The rest would be stored in hydrogen and exported. As the OTECs pumped enormous quantities of cold water from the ocean depths, they would bring nitrogen up to the surface with them. This nitrogen would cause the algae population to explode. Algae would be cultivated in containment ponds surrounding the sea cities.

As the marine colonies grew and seeded more colonies, they would act to cool the equatorial waters. This would help offset global warming somewhat. To offset it still further, the colonies could allow part of their harvest of algae to sink into the oceans. This would act as a carbon sponge, because algae are 20% carbon by weight. If all of the algae were used as food, the carbon would all return to the atmosphere. Some of the protein bounty would be lost, but millions of tons of carbon dioxide could be removed from the atmosphere of Earth each year.

It’s time to go off on a digression now, about the way that life is recycled at sea.

“At sea, nutrients are not recycled the same way as on land. If they were, life on the seas would be far more plentiful than it is. At sea, the nutrient cycle is very indirect. A plant or animal will scavenge nutrients from its environment and bind them up in its body during the course of its life; then, when the organism dies, it sinks into the depths, taking its nutrients with it. These nutrients remain locked away in the depths until brought to the surface again – usually after a lapse of a thousand years or more. Consequently, a millennium’s worth of nutrients are concentrated in the deep waters of the world’s oceans.”

To understand the significance of this stuff about nitrogen, you need to know that plants form the base of the food chain and that plants need nitrogen. You need to know that the Green Revolution in increasing agricultural productivity was enabled by nitrogen that was extracted from oil. You need to know that we are running out of oil and that it is becoming more and more expensive to extract the remaining oil. And you need to realize that Peak Oil doesn’t just imply trouble for the gasoline on which our cars run but also implies massive food shortages and starvation.

Furthermore, you should know that algae use nitrogen a lot more efficiently than the plants that people grow for food and that people can eat algae. In fact, blue-green algae – the oldest kind – is nearly a perfect food for people. If you’re health conscious and open-minded, maybe you have had a Spirulina protein shake before. Or, perhaps not. In any case, eating algae is better than starving. Savage points out, however, that we should not assume that people will eat anything if they are starving. Efforts to feed the hungry have foundered before on the assumption that people who are starving are not choosey about what they eat. In fact, they are. Therefore, he has even thought of a way to to make a nutritious, high-protein bread with this algae and to make sure that the bread will not be green in color.

There’s more. The containment ponds used to grow the algae would suffer from the problem of biofouling. The kind of algae that people would eat would grow on the surface of the ponds and be removed frequently, but another kind of algae – grass algae – would grow on the sides and bottoms of the ponds. This problem would present an opportunity, because shellfish could be used to eat this grass algae, and then the shellfish could be harvested. For instance, the Carribean King Crab feeds on this type of algae. This type of crab grows large and has lots of delicate, tender white meat. The next problem (and opportunity) that would be introduced would be the problem of the shells of all of these shellfish. The shells would become a source of chitin, which can be used to make paper, enabling the sea cities to be self-sufficient in paper products. Limestone and magnesium would also be extracted from the shells. The limestone would be used for finishing plaster. The magnesium would be used for another purpose, about which I’ll write more further on. Pearls could also be harvested from the farming of oysters. The colonies could export pearls and use part of the money obtained from these exports to fund space travel.

Just outside the containment ponds, seaweed would be cultivated. It would not only clean up the deep water effluent, but it would also be used in the production of algin. Algin can be used to make a lot of useful products, but Savage is proposing to use it mainly for textiles. Algin would produce textiles of a silky texture. The sea cities would be self-suffient in not only paper but also textiles. Learning self-sufficiency in the sea cities would be important to preparing humans for life in space colonies. At every opportunity, Savage tries to think of a way that the sea cities can use something harvested in their immediate vicinities to meet all of their needs.

Due to all of the processing of shellfish, there would be a lot of scrap animal protein, and this protein could be used for fish farming. Various species of carnvorous fish could be suspended in cages in the seaweed and fed pellets made from the scrap protein. The colony could export fish.

You may have been wondering what these sea cities would be constructed of and how the materials would be brought out to sea. The answer is that the cities would not be constructed. They would be grown. In fact, they could be viewed as a kind of macro-organism. There are aquatic snails that build bubble floats and use these floats to suspend themselves. Bubbles that are packed together naturally cohere into a hexagonal grid. This kind of structure is naturally buoyant and stable. The bubbles would be made of concrete, and the concrete would be grown like seashells. The accretion of this type of cement would be caused by passing an electric current through a metal grid. Calcium carbonate in the sea water bonds electrochemically to charged metal. The resultant coating is as hard as cement. Most of the waters on the surface of the ocean, especially near the equator, are full of dissolved calcium carbonate ions that are positively charged. This same mineral is found in the things we know as marble, limestone, seashells and Portland cement.

The metal grids that accreted the calcium carbonate would be made of magnesium, which would also be extracted from sea water. Sea water is the main source of magnesium produced in the United States. Magnesium can be extracted from it by mixing it with calcium oxide. Calcium oxide can be produced by heating sea shells in the presence of oxygen. Magnesium is the lightest of all structural metals and is a good conductor of electricity. In its pure form, it is soluble in sea water, but when alloyed with manganese and anodized, it can be made corrosion-proof.

To summarize, then, sea colonies can grow enough food and produce enough power to feed and power the world while being self-suffient, preparing people to live in space and acting as carbon sinks to offset global warming. Their structures can be grown in an organic manner, using materials that are already found in the sea, powered by a source of power that is already ready to be tapped in the sea. People can sustain the population we have now, while preparing to colonize space, in spite of Peak Oil, while offsetting global warming and global climate change, without displacing any existing ecosystem on Earth. Now, tell me what the engineering or scientific flaws are in this plan. Are there any? Or are the barriers to enacting this kind of a plan solely psychological, social and political in nature?

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