Farm in a box

An inventor in Kenya has come up with a farm kit he claims can grow enough plants and livestock to feed a family in a space the size of a small car.

The 'aquaponic' system combines growing beds with a tank for rearing edible fish or shrimps. The two systems work in harmony using minimal amounts of energy and water.

If this sounds like the stuff of science fiction, its creator assures me the idea has been around for centuries and is beguilingly simple. That said, he has little doubt about its potential to revolutionise the way food is produced in the future.

I meet Heino Dahmen in a sprawling garage on the outskirts of the port city of Mombasa. He has run this business and an adjoining shipyard on the Mtwapa Creek for 20 years, but now devotes almost all his time to a bewildering array of engineering projects.

Heino was an early pioneer of green roofs, also known as living roofs, in his native Germany in the 1980s. When the Berlin wall came down, he won a series of lucrative contracts to install many such roofs in the East of the city.

I jog to keep up as he explains that he recently broke his toe. His pace is matched only by our conversation which leaps from nutrition in Africa to vertical farming in Singapore with an agility that is sometimes hard to follow.

The issue of food scarcity first crossed his radar during a visit to northern Kenya, where a dry climate causes periodic famines. At Dadaab refugee camp he was struck by the lack of nutritional value in the sacks of food provided by aid agencies and governments, and began wondering how fresh food could be grown on site.

Artists' impression of the aquaponic kit stocked with fish and growing vegetables

The word aquaponics is a hybrid of aquaculture and hydroponics. It refers to a system that integrates the farming of fish or prawns with the growing of plants without any soil.

In traditional aquaculture, the water becomes polluted by waste from the fish if it is not cleaned regularly. Aquaculture gets around this problem by feeding the waste to the plants.

"The fish feed the plants, the plants clean the water for the fish. They live in a symbiosis all together here," Heino explains as he leads me down to the shipyard to see his beloved "kitchen garden". We are surrounded by hulls and outboard engines in various states of disrepair. He throws open a large barn door in one of the boat sheds to reveal his aquaponic laboratory.

Standing in front of us is a fibreglass structure that appears to be sprouting leaves. At its centre is a pond, where three or four plump tilapia bob lazily in a bath of sunlight. Surrounding the pond are two narrow terraces of gravel with neat rows of seedlings.

A small solar pump delivers a steady trickle of water from the pond to the growing beds. Every half an hour, when the beds become full, the cleansed water flushes back out into the pond. This continuous circulation means that water consumption is very low. Indeed, the entire unit requires just a little energy and some fish food to keep running indefinitely.

Heino assures me that the Internet it flooded with similar (albeit inferior) units, but promises that what I am about to see is unique. We walk round the back of the unit and crawl into a dark enclosure underneath the pond and growing beds.

The air is much cooler here owing to the constant evaporation of water from the growing beds above our heads. Heino explains that this "naturally-created cooler box" would be the ideal place to keep chickens or rabbits, or even to cultivate mushrooms.

This miniature farm could in theory provide, or at least supplement, a family diet. In a world of depleted soil and ballooning air miles, Heino believes aquaponics offers an answer. The system could even work indoors, if set up under a bank of low-power LED lights.

It is easy to see how this could appeal to those interested in organic produce and reducing their food miles, yet Heino insists it is more of a "lifestyle device". He points out that the unit cost - currently around $5,000 - makes it unsuitable for people living in poverty.

He leads me to another device consisting of four vertical drainpipes that meet at the top and bottom. Each of the vertical pipes has dozens of small scoops cuts out of it in which seedlings are growing.

"These four pipes grow 340 plants on one square metre," Heino tells me proudly as he inspects a bushy little basil plant.

Unlike the previous system, this is a pure hydroponic system and does not contain a fish pond. Instead, nutrients are provided in the form of compost which is put into a small filter at the tower's base.

A solar pump delivers water from the base back up to the crown where it trickles down through the gravel inside each of the pipes. The continuous and reliable supply of nutrients mean that the plants do not have to waste energy on extensive root structures.

"These seeds were planted four days ago," he says pointing to some tomato plants. "They are now 10cm tall - that's an enormous growth rate."

The entire structure is built from plastic drainage pipes and connectors that "can be purchased in any hardware shop". Heino believes the low cost and ease of construction, as well as the metre-square footprint, make it ideal for the mass market.

"Poor people have to move often so they can take that thing apart and it moves with them. Their own food production, their garden, can move with them to another house."

"I can't see why we should have any food crisis … If you bring [some units] there tomorrow, then one month later people will start eating and it will never stop."

Heino is the first to admit that the idea of aquaponics is not new: industry, universities and even some communities in Australia and the US have been using it for years. His contribution has been to strip down the technology to its bare essentials and to package it in a way that could be used in hospitals, schools and refugee camps as well as in private homes.

He is currently seeking a local celebrity to act as an ambassador in order to catch the eye of philanthropists and aid agencies.

Listen to an audio tour of Heino's aquaponic laboratory (as featured in episode #53 of the CoolGreen podcast) below:

listen to ‘The world's smallest farm’ on Audioboo

Read more about the aquaponics project here

See some Heino's other engineering projects here