Danish initiative to house pigs with tomatoes

Pigs and tomatoes may be a winning combination on the breakfast plate, but how about housing them together? Sarah Trickett reports

A housing unit with pigs at ground level and tomato plants in greenhouses on the first floor may seem like a crazy idea, but such a unit could soon be taking shape in Denmark, according to architect Nee Rentz-Petersen.

With 20% of Danish greenhouse gas emissions coming from agriculture, the “Pig City” concept hinges on reducing CO2 emissions and making pig farming sustainable and odour free.

“The unit is planned to be carbon neutral in production and would combine an annual production of about 20,000 finishers (750 sows) with 1100t of tomatoes. The idea is the greenhouses will benefit from the heat generated from the pigs while the manure will be used as fertiliser,” explained Ms Rentz-Petersen, who took on the project for her PhD thesis.

Estimated to cost about 100m DKK (£12.3m), the 27,000 sq m areas on each floor is still in the planning phase but aims to be environmentally friendly, have high welfare conditions and create a better work environment. It will be a first for the industry.

The synergy effects are obvious, explains Ms Rentz-Peterson. “Tomatoes need fertiliser to grow and pig manure contains phosphate and ammonia, so it will be a win-win situation,” she said.

The building will operate a birth-to-slaughter principle, meaning all pigs remain in one of 26 housing units until slaughter. Welfare will also be maximised by using larger sow stalls, providing straw and loose-housing dry sows. The unit will also contain an abattoir, removing stress from transportation.

A biogas plant and slurry separator will also be installed, with slurry and other waste going to the biogas plant and surplus energy used to heat the greenhouses. The purified liquid fraction will be used to water the plants.

If planning permission allows, building will commence next year and will be finished by 2012. The unit will also contain a visitors centre and farm shop.