Offshore urban developments emerge as a potential pressure valve for coastal housing shortages
The prospect of large-scale floating cities is moving from concept to early implementation, raising potential implications for housing supply, land values and mortgage markets in coastal nations such as Australia.
Professor Chien Ming Wang of the University of Queensland, a global specialist in very large floating structures (VLFS), has spent more than two decades studying how vast engineered platforms could support permanent communities at sea, complete with residential, commercial and civic uses.
His interest was sharpened in the late 1990s after Japan’s Mega Float project in Tokyo Bay, where a one-kilometre floating runway demonstrated that massive structures could remain stable enough for sensitive navigation equipment, despite ocean movement.
With the United Nations projecting billions more people living in cities by 2030 and finite land available near major metropolitan centres, Wang (pictured right) argues that the sea represents a significant, largely untapped, spatial resource.
“We have created entire civilisations on land, but we have not utilised the ocean anywhere close to our capability,” he said. “Right now, scientists say only 5% of the ocean has been explored. It’s just a speck.”
He noted that oceans also offer access to renewable energy sources including wind, waves, tides and solar radiation, as well as opportunities for desalinated water supply and advanced aquaculture. “We’re even developing optimised commercial fishing methods that would allow us to not just survive on the sea, but thrive,” he said.
To advance these concepts, Wang works with an international team of engineers and researchers in Norway, Japan and Singapore on cost-effective production methods and new concrete composites designed for long-term marine exposure.
“Not only are the materials and technical innovations catching up to our dreaming, we now also understand how to do sophisticated hydrodynamic analysis, even for very complex structures,” he added.
Potential relevance to Australia’s housing market
For Australia, where most of the population is concentrated in a handful of coastal cities, the question is whether such developments could one day supplement constrained urban land supply.
Wang considers the idea feasible in principle, particularly adjacent to high-value coastal capitals such as Brisbane, Sydney, Melbourne and Perth, where land prices and density constraints are most acute.
“A lot of people flock to these cities…so the land (value) goes up and it comes a point where the land cost is so high that it makes sense to expand the construction of housing onto adjacent space…in this case the ocean,” he pointed out.
However, the economics remain challenging. Large-scale floating platforms are expected to require capital outlays in excess of $1 billion, alongside the cost of separate floating breakwaters to shield developments from waves and wind. Concept designs typically limit residential buildings to around six storeys, with integrated berths or marinas for vessels.
For mortgage professionals, any future Australian project of this type would raise fundamental questions about land tenure, security structures, valuation methodologies, insurance coverage and regulatory treatment. Issues such as title registration, acceptable collateral standards, disaster risk and resale liquidity would need to be addressed before mainstream mortgage lending could be extended at scale.
If large floating cities were to emerge off Australia’s coastline, they could introduce a new class of waterfront housing and reshape the discussion on how to accommodate population growth where traditional land supply is limited.
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