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City on the Sea, Part III

By Liz Clift

Editor’s Note: This is the final segment of a 3-part blog on the future of seasteading, that posted on consecutive Tuesdays. Check out Part I and Part II.


Many of the models on the Seasteading Institute website showed solar energy capture, with solar fields taking up part of the city, or covering rooftops. Unfortunately, it is still difficult to store solar energy, but depending on the location of the floating city perhaps this would be only a minor problem (if it was located in a place in the world with abundant sunshine).

As long as we’re talking about solar energy—what does this look like without solar panels? The Seasteading institute suggests that since the tropical oceans absorb 3x the amount of energy each day that the world currently consumes, there are opportunities for research, development, and harnessing. The Institute also suggests that Ocean Thermal Energy Conversion provides an opportunity for generating power (for the floating city as well as land-based nations).

There’s also the potential for capturing wave energy. The Bureau of Ocean Energy Management (BOEM) notes that wave energy, at least along the coast of the United States has tremendous potential as an energy source. “[T]he total wave energy resource along the outer continental shelf [was estimated] at 2,640 terawatt hours/year (TWh/yr).” The energy potential in this is significant as just one TWh/yr can supply a little shy of 94,000 average US homes with power annually. However, wave energy cannot be fully harnessed due to things like shipping, commercial fishing, and environmental concerns in sensitive areas.

Harnessing wind energy is something we’ve already started to do, and with a fair amount of success. Depending on the location, wind energy has a lot of potential (pun intended) for this type of project. It would be fairly easy to set up wind generation stations on the roofs of buildings or as other parts of the landscape.

Compost piles can be used to heat water or to generate biogas (through the use of a biodigester) for use in cooking. If done properly, either of these options will have little to no odor, and provide an opportunity for dealing with the floating city’s waste.

Partially-constructed compost mound water heater. Image from: Cornell University.

Partially-constructed compost mound water heater. Image from: Cornell University.

Other Concerns

My colleague brought up the question of what happens to sea life beneath these cities, and I think that really depends. If the cities are static (i.e. more or less permanently moored), this has the potential to radically alter the way that sea life looks below them, since fewer-to-no UV rays would be able to extend into those parts of the ocean. The materials used would also impact the suitability of these cities to become anchor points for crustaceans, seaweeds, and other ocean life that prefers to anchor to a particular place rather than drifting or floating.

We may have some reference points in the form of oil and gas (O&G) platforms, which are generally designed to last 20 to 30 years, though some are maintained to last longer. The topsides of most O&G platforms include living quarters that consist of an average of 20 rooms, with thirty beds, a cooking facility, a galley, a landing pad for helicopters and other features. Most fixed structure standing oil platforms can stretch as deep as 1,500 feet, and may stretch across several pilings or ‘legs.’ The British Petroleum Oil Rig in the Gulf of Mexico that lead to the deep-water horizon disaster was 400 feet by 250 feet, roughly the size of two football fields, and supported a crew of 130 people. Some platform structures are even larger, in fact many of today’s platforms are essentially small cities equipped with cafeterias, lounges, and some even have small movie theatres.

Life on an oil platform. Image from: Blue Latitudes.

Life on an oil platform. Image from: Blue Latitudes.

While the aforementioned O&G structures are fairly typical to the industry as we’ve understood it in the past, there may also be a model in the world’s largest ship ever built, and the first floating liquefied natural gas platform, which is scheduled to begin drilling later this year. Although this is a moveable facility, the ship is expected to remain moored for 25 years. The sheer size of these structures alter the ocean life around them—but they also provide new opportunities for colonization, which leads to species congregation near the structure and/or greater species diversity.

On the other hand, if these cities are unmoored (truly floating cities), that changes the impact to sea life immediately beneath them—and likely decreases the risk of an area receiving little or no UV light. It also increases the risk that these floating cities would drift into deeper waters, where wave power could change, and where ocean currents could sweep them far adrift (and therefore outside of the range of mainland emergency services, among other things). There would also be the risk that truly unmoored floating cities would break apart in rougher waters without ways to reunite or end up in the path of a barge as they drifted into a shipping channel. They might even end up in the territorial waters of a hostile nation or face other, unexpected interpersonal or geopolitical problems.

These considerations must be taken into account to keep the residents of the floating city safe.


While the reality of a floating city might be years (or longer) away, it’s interesting to consider some of the problems (and solutions!) which might arise from such a place. Floating cities, in some ways, force us to consider what it might be like to dramatically restructure our lives—and potentially on a more permanent basis than what occurs with remote research or O&G facilities.

Floating cities also provide an opportunity to expand our conception of what SLR planning (and resiliency planning, in general) could look like and how technology, engineering, ecology, and a spot of idealism might play a role in shaping these types of places.

Floating cities are not exactly a new concept—but so far, none have come to fruition in the ways conceived by this project. As mentioned earlier, O&G platforms, in many ways, serve as self-contained cities for short periods of time. People have also approached this idea as a way to divest themselves from global politics or economics—for reasons focused on self-governance, participatory governance, and economic freedom.

But, these projects have, so far, failed to become reality because of the tremendous expense associated not only with the conceptual design and development, but also with the actual construction of such places. This price tag will need to be addressed, as will the idea of who, exactly gets to live in places with such a high price tag. Will these options truly be open to people who lose their homes and livelihoods due to sea level rise?

Although I’ve focused on floating cities for the purpose of this blog post—because of the MOU signed between the Seasteading Institute and French Polynesia—the research for this blog has also taken me on an adventure of exploring how these floating structures might look as research centers or farms, and the potential opportunities these options present as well (algae farming, anyone?).


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