With enough money and resources anything is possible, but creating closed systems that mimic what we get from the earth for free is extremely energy intensive.

For example, our atmosphere has a massive volume, which means it’s an excellent sink for indoor pollutants. To reduce indoor pollution (dust, harmful gases, viruses etc.) in our buildings today, the air is not purified as much as it is diluted with outdoor air.

Directly purifying air (ie. forcing it through a filter) is of course possible, but filtering large volumes of air with no external sink to an increasing level of purity basically creates an exponential energy use curve. The system will also become more complex and redundant, because without an environment to fall back on, the risk of failure becomes unacceptable.

So the degree to which an arcology’s systems are separated from the earths natural systems and sinks dictate their complexity and energy use. A space station arcology would use exponentially more energy and have exponentially more complex systems than an arcology located in even the most uninhabitable regions on earth.

The closest thing today that we have to an arcology is a nuclear submarine, probably. Its clean, energy dense reactor can desalinate seawater and generate oxygen from hydrolysis. If you didn’t need to feed the crew, it can theoretically maintain a habitable environment as long as the reactor is fueled.

Fusion power would go a long way towards making arcologies viable by allowing us to design viable systems further along the exponential energy consumption curve.

I just find it so strange that governments are still devoting attention to this high-exergy transport method. Who is even benefiting from this at this point?