Shipping Container as Greenhouses
Most of us know that shipping containers are the basis of world trade! These standardized rugged steel boxes carry everything from rubber ducks to cars across the world. But not many know that shipping containers have a second life- as greenhouses!
Food in the City
Our cities are polluted and cramped, and yet they are also where most of our population is. But they aren’t where most of our food is grown which is typically hundreds or thousands of miles away. For years, some people have tried urban farming using tiny slivers of open empty space to create backdoor farms. And of course there is also a long history of urban greenhouses for everything from marijuana to tomatoes.
Urban greenhouses are successful across the globe and have a proven economic potential. The most obvious drawback is that the walls and roof are of course made of a single layer of clear glass or plastic. This obviously means you get lots of natural light- even more if you use skylights- but there is a natural limitation in sunset and sunrise times. Similarly, because of the lack of insulation temperatures are not dissimilar from the external environment. Artificial sodium lighting and electrical heating can be used to extend the growing season into winter but can be very expensive to run, especially at scale.
Growing Indoor Made Easier
Indoor Farming. Greenhouse Container Farms
The alternative Greenhouse
Recently entrepreneurs have begun using shipping containers as farms. A used shipping container is cleaned, insulated and lined to prepare it for trays of plants. A standard container, 40ft long and refitted into a grow container, needs just flat land, water and electricity to start working- they can literally fit in a parking lot.
Being completely sealed from the outside world means sunlight can be 24/7 and plants can get water and nutrients as they need- it can all be set up electronically. Most container farms get multiple harvests a year. And even better there is limited loss from pests as it is sealed and if your customers are on the same block there is no wastage from transport.
It gets really interesting when you start maximizing the efficiency of your operation. Many growers lean toward hydroponic systems where you do away with soil completely and bathe the plants roots in a cocktail of nutrients. You can also change lighting to get dramatic effects- you can get to an indoor shipping container greenhouse!
Light Issues
Indoor grow systems typically use high-pressure sodium lights. There is a long history of using these in agriculture to extend the growing season of tomatoes in greenhouses and sodium lighting is widespread in winter months in the northern hemisphere. Sodium lights quickly run very hot, which isn’t at all great for the confined space of a shipping container farm. Ventilation and cooling needs to be ramped up and even then plants can’t come anywhere near the fiercely hot sodium light. New LED technology runs at much lower temperatures, so you can install them inches from the plant.
LEDs have both fallen in price and improved their performance often equal to or exceeding older methods. LEDs are of course widely used and are a favorite when you need energy efficiency, low/no maintenance, spectral control, and beam control. However improvements in output are a recent phenomenon.
In fact, depending on what you grow, your light arrangement and even light frequency can be tailored for your crop across its growth cycle. Most growers also use what’s called interlighting, placing lights nearor between the plants. Running either vertically or horizontally, interlighting delivers light to the lower foliage that doesn’t receive much direct light from above as the plant grows.
Shipping container greenhouses: the way forward?
With 24/7 lighting, controlled nutrients and environment you end up with a packaged high yield farm- in fact, a whole farm in a box. Without worrying about the weather or pests, the grower can maintain multiple harvest cycles. It’s easily possible to maintain a better yield and multiple crops per year.
This is fantastic for crops such as cannabis which required intense and quite particular lighting. But it is also incredibly valuable for food products as well, such as leafy greens, herbs and microgreens.
There are lots of questions remaining. Fungus can be an issue indoors with no UV exposure. Plant circadian rhythm is still not well known. Nevertheless, the use of LEDs plants new seeds which may ensure a bountiful future.