Got a Lawn? Then you have free hot water!

The Victorians knew quite a lot about the art of gardening and many of their methods were simply ingenious! Hot Beds for example utilised rotting compost in order to heat veg beds to get Winter crops or to grow exotic plants in the UK climate.

Hot Composting is no secret, but it is considered an art. Indeed the term Master Composter is sometimes used for those who use this method. Hot composting relies on getting the correct balance of carbon to nitrogen in your compost heap. If you get it spot on, the heap will heat rapidly producing excellent compost. It is important though to keep hot heaps moist otherwise they can burst into flames! The beautiful thing about using compost to heat water is that it isn’t reliant on the sun. Many other passive water heating methods only function during daylight hours, but compost microbes are at work 24/7.

So…in theory its a good idea, but how does it work in practise? Pretty well is the answer. We built our simple experimental tank using an 80L plastic bin. This was simply placed on the ground and a compost heap built around it. If you want sure fire heating, grass clippings are ideal as they contain the perfect balance of water, carbon and nitrogen. Pile them up and within a day or two you can feel the heat if you pop your hand in! The idea works best if the heap is insulated to keep the heat in and it must be sufficiently large to be able to build up a good temperature. Keep it moist and consider covering with a waterproof layer if the weather is hot and dry.

The pic below shows our first trail with the insulation and some of the compost removed. We used alternating layers of high nitrogen duck manure and the high carbon sawdust/newspaper from a rabbit cage (a friend couldn’t dispose of it in council recycling because the presence of paper makes it mixed waste. We are more than happy to compost it though!).

The 80L of water in the bin heated up to 35oC within a week and has sustained that temperature since, our grass clipping trails reached 60oC within a few days, so for foolproof heating best to stick with grass clippings. Keep topping the heap up as it collapses with fresh clippings and every few months remove the compost from the bottom and top up with new if the temp starts to fall.

Now we need to start on trails where some of the hot water is removed and replaced with cold (as if the water tank were plumbed into a hot water system). This could be an ideal way to preheat water going into passive solar water heaters….in our case it is perfect for washing dishes, the next version will have outlet tubes so that we can start trying it to supply a shower!

Keep an eye on the blog for more updates on progress!

This month we will be moving into our new farm which is to be developed as a permaculture demonstration & teaching facility. Check back to our new blog for photos and upates of our progress!

A new study by the University of Michigan has shown that organic farming in industrialised countries can produce comparable yields to conventional farming, and up to three times the yields currently obtained in less-industrialised countries.

This is groundbreaking research, and adds weight to environmentalists’ arguments that the world certainly wouldn’t starve if we all farmed organically.

Listen to one of the lead authors explaining her group’s findings from The Ecologist HERE.