The ability to bio-digest cow manure has opened up a significant rethink of the income streams available to dairy and beef farmers. The Bio Gen Cool, a bio-digester developed by Natural Systems with partners Waste Solutions, turns cow manure into methane gas and then uses that power to chill milk. However, with a little lateral thinking, the gas can also be used to generate an income for farmers.

A bio-digester feeding a generator will be able to meet all of a farm's electrical needs, perhaps supply methane to all the farm vehicles, and export electricity or scrubbed methane gas to the national grid.

How can the most manure be collected to gain the most benefit? Cows will spend 60% of the day undercover if it is available. If a covered area was created for the cows, this would make manure collection easy.

Supplementary feeds could be brought to the covered area. More milk fat will be generated and more manure would be made and collected. The cows will be healthier, conceive more easily, and the milking season may also be able to be extended.

There is also the possibility that if the cows can be milked near or in the covered home, they will not need to be brought in from the fields. This would be ideal for robotic milking.

Also, electric fence strip grazing can be utilised to manage the hoof damage to the field and to limit how much the cows eat.

If the cows have alternate free range paddocks attached to their covered homes, the rest of the farm can be available for supplementary feed production, or if supplementary feed production is not suitable, farmers could have more cows with their free range paddocks and covered homes.

There is a bio-digester program that is currently being trialled on a North Canterbury farm, utilising a timber tank from an Auckland based company, Timbertank Enterprises.

The benefits of using a Timbertank in this type of project are numerous. They have a long life, and can be dismantled and relocated extremely easily. Following Waste Solutions' specific design details, Timbertank Enterprises were able to build a specialised tank and parts for the digester.

For water storage, the trend in dairy farms is generally to buy a plastic tank, and then, when that tank's capability is outgrown, to buy another tank, and so on until there is a cluster of tanks taking up valuable space on the farm. While plastic tanks generally hold around 30m3, Timbertanks can range in size from 100 - 6000m3.

Timbertank Enterprises is currently working on a 1 1/2 million litre tank that is 20m in diameter. By increasing this diameter by 6m, which is something we can easily do by modifying the existing tank, we can double the volume capability - bringing it to 3 million litres. This kind of modification and reuse adds up to significant savings for farmers.

While currently the earning power of traditional dairy farms is limited by their waste management processes overloading the environment, the combination of a timber tank and bio-digester can open up new possibilities to restructure a farm and generate additional income.

There is no reason why this concept would not work for beef farmers as well.