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Using Pigs to Grow Tomatoes with Biogas

by 5m Editor
1 January 2010, at 12:00am

An innovative eco-friendly pig farm of the future is the dream of a Danish pig farmer, Soren Hansen and the concept of a PhD architecture student, Nee Rentz Petersen, writes ThePigSite senior editor, Chris Harris.

The dream system that completely integrates pig housing with the final slaughterhouse as well as using the waste products to heat and power the building and a massive glasshouse growing tomatoes was one of the winning designs in a competition run by the Danish financial institution, Realdania.

The futuristic two-storey building, with pigs on the ground floor and tomatoes growing above, is now about to see the light of day thanks to a consortium comprising Gottlieb Paludan Architects. AgroTech and Nee Rentz-Petersen.

The "Pig City" costing between 100 and 120 million Danish kroner (DKK) will house 20,000 finishers and grow 1,100 tonnes of tomatoes. The concept is based on reducing carbon dioxide (CO2) emissions and making pig farming sustainable and odour-free.

"The idea is that the greenhouses will benefit from the heat generated from the pigs while the manure will be used as fertiliser," said Soren Hansen.

"The end result is CO2-neutral and odour-free pig production."

Ms Rentz-Petersen said that with the tomatoes needing fertiliser to grow and the pig manure containing phosphate and ammonia, the synergy is obvious.

"With a focus in the highly relevant global climate debate, the current project has zoomed in on reducing the CO2 impact of modern industrialised production," she said.

"By integrating modern technologies, it ha been possible to create a vision for modern pig farming that not only minimises environmental impact, the project eliminates problems such as ammonia pollution, delivery of manure to the fields, bad smells, high level energy consumption and CO2 emissions."

The project also envisages having job rotation for the employees, hopefully offering a better working environment and making it easier to retain the workers.

The pig project will be a birth to slaughter unit, with the pigs remaining in the same place through to slaughter, enhancing animal welfare.

The welfare side is also considered in the larger-than-average stall, straw for the sows during the period up to farrowing and a loose housing system for the sows. The piglets are born in one of the 26 housing units.

Because the system includes its own abattoir, there is no stress caused by transportation and this, in turn, improves animal welfare and meat quality as well as reducing the chances of zoonoses.

The project has designed the biogas and slurry separation plant to maximise the financial benefits and have the minimal environmental impact.

For the work environment, the pig house has an improved ventilation system at floor level with a biological filter that reduces dust and exposure to ammonia.

The biogas plant is supplied by the manure, slurry and waste and the surplus heat that is created will be used to heat the greenhouses.

Purified liquid from the slurry separation will be used to water the tomatoes plants in the greenhouse. Another environmental part of the design is that rain water will be collected and stored as part of the irrigation.

The dry matter from the separator will be used as fertiliser for the tomatoes and any excess can be sold either locally or exported.

The project that will cover around 20,000 square metres is hoped to be started early next year and completed in 2012. The design has drawn out to ensure that there is minimal visual environmental impact with wind screens around the building.

"The project demonstrates how agriculture production can be combined with respect for animals, humans and the environment with greater profitability," said Ms Rentz-Petersen.


Artist's impression of "Pig City".

December 2009