Inspired by the humble old greenhouse, a futuristic self-contained food ecosystem was recently on display at Expo 2025 Osaka-Kansai in Japan, offering us a glimpse at a how we might one day have "farm to table" on our apartment block rooftops or in small urban spaces. Think of it as a tiny house of produce.
Known as “Inochi no Izumi” (いのちの湧水), or "Source of Life," the dome became one of the standout pieces of ingenuity on show at the Osaka Health Pavilion on Yumeshima Island. The 6.4-m-high (21-ft), 7-m-diameter (23-ft) dome, built to symbolize the Earth, sits atop a base containing four different water zones that provide the living engine of this closed-loop ecoystem.
The dome itself has a surface area of 128 sq m (1,378 sq ft), made up of transparent ethylene tetrafluoroethylene (ETFE) panels for the outer skin, supported by VikingDome's T-STAR system of 245 steel structural bars, connected with 76 joins on the sphere and 10 on the base. The entire unit, with materials transported to the site in three pallets, weighs a massive 2,111 kg (4,655 lb).
The dome itself is designed to maximize sunlight and maintain a stable internal climate – but the real innovation is found inside it. A horizontally divided aquatic base supports four vertically stacked plant layers. Rather than a conventional floor-by-floor layout, the dome houses a kind of ecological cross-section, where different salinity zones and their matching crops work together in a regulated loop.
At the base are four compartments housing seawater, brackish water and two freshwater tanks. Each supports aquatic species adapted to those conditions, from marine fish and shellfish to carp-like freshwater species. These animals form the starting point of the nutrient cycle crucial for the life above. As they excrete ammonia-rich waste, specialized microbes convert it first into nitrites and then into plant-usable nitrates.
Directly above the tanks, four matching bands of hydroponic growing beds rise in a tiered column. Salt-tolerant plants, such as halophytes, grow above the seawater tank, thriving on nutrient-rich water that would kill conventional vegetables. Sea grapes grow in the water, while sea purslane and sea asparagus grow above the tank housed with red seabream, black porgy, red-spotted grouper and Malabar grouper. Then, semi-salt-tolerant vegetables plants like tomato sit above the brackish-water zone, which houses Japanese pufferfish and ornamental carp.
Above one of the freshwater systems are “functional vegetables” – greens like herbs and lettuces with concentrated nutrients that do particularly well in controlled hydroponic conditions. Their water comes from the tank occupied by sturgeon. The beds can also be rotated horizontally via a built-in motor. At the very top, on the fourth tier, are rows of edible flowers including nasturtium, bougainvillea and marigold.
Water from each tank is pumped upward to irrigate its corresponding plant zone. As the plants remove nitrogen compounds and other nutrients, the purified water flows back into each aquatic zone below. As such, the system produces next to no waste – a cyclic ecosystem modeled on nature (like wetlands cycling, for example) but optimized for human food production.
Developed in collaboration with Osaka Metropolitan University’s Plant Factory R&D Center and the Tokyo University of Marine Science and Technology, the system demonstrates how future cities could grow food in such compact, resource-efficient ecosystems. It also highlights a different kind of biodiversity – that of agriculture. The broader the range of usable plant and aquatic species, the more resilient – and self-sufficient – the system becomes.
While the Source of Life was indeed an exhibition, so there are some practical questions about the fish housed in the tanks at the base, it nonetheless demonstrated how natural recycling can help to produce food and reduce waste, and it's not a stretch to imagine this modular aquaponics system becoming a reality on rooftops, in dense urban areas or in land-poor regions where farming is limited. In disaster-prone areas, closed-loop systems like this could offer stable, decentralized food production independent of soil quality or access to large supplies of water.
It's also a clever look at how sustainable agriculture doesn’t always require new technologies so much as a deeper understanding of ecology – something that's often lost in agribusiness and large-scale commercial farming. As we look for low-emission, sustainable ways to feed growing urban populations, this dome proposes that one answer may lie in us better harnessing the power of nature.
For more on the build, check out this video. And for more on the project you can check out a 25-page plan outline here (PDF).
Source: Osaka Healthcare Pavilion
