Sunday, April 23, 2006
DIY Vegetarian Electricity
The day has finally arrived!
Following a few test runs, my Lister engine and generator was now ready to be run on vegetable oil.
The whole point of this project is to make heat and power from renewable fuels, and to reduce my consumption of fossil fuels. The Lister engine is an ideal way of converting waste vegetable oil into a viable domestic energy source.
I managed to pick up a scrap exhaust pipe from the skip at my local exhaust centre, and that was fitted in a somewhat temporary fashion - but worked very well in taking the majority of the noise out of the exhaust note.
A coil of microbore copper tubing was wound around the hot exhaust pipe - where it emerges from the cylinder head, and this was connected up between the fuel tank and fuel filter. The 16 turns of tubing acts as a fuel pre-heater and it warms up the vegetable oil sufficiently for it to flow like diesel. The Lister doesn't care what fuel it runs on, but I do!
Once heated up, the Lister runs normally on the warmed vegetable oil, without missing a beat. A temporary water cooling tank has been rigged up on the right handside of the engine. Eventually this will be replaced with a heat exchanger that will provide hot water an contribute to the central heating system - thus allowing me to burn less gas next winter.
The output from the alternator will be connected to a battery bank and inverter system that will supply power to the house.
This allows the engine to be run efficiently at full power for about 5 hours per day, using just about a gallon of waste vegetable oil, and recharging the battery bank. The engine is capable of generating 3kW of electricity - enough to power a kettle, but most of the time, my house only needs about 1/20th of this. Charging the batteries during morning and the early part of the afternoon, when houshold usage is low, will then allow us to run off inverted battery power for the remainder of the day.
The key to most renewable systems is the ability to store energy from times of plenty, and then trickle it out at the rate at which you need it. I suppose the same can be said for solar heating systems and rain water collection - it's just a case of storage, whereas grid systems lead you to believe that you can take as much as you want, whenever you want and it will always be available.
There are still several tasks to perform on this project. Firstly I need to build a new shed around the engine. I hope to use straw bale construction for this. The straw bales will not only attenuate a lot of the general engine noise, but will also offer good heat insulation from the elements.
Straw bales are readily available, quick to build with renewable resource and can be constructed without using excessive amounts of other building materials - such as cement and concrete blocks. The outside of the shed will be clad in shiplap boards - so that it looks like any other garden shed.
This building will house the whole of my renewable energy system, engine, inverter, batteries and veg oil filtering tanks. On the roof will be my solar water heater, which can also be used for pre-heating veg oil or warming the engine on cold but bright mornings.
Connected to the house by just two heating pipes and a power cable, the whole system can be isolated, when not in use, and the house returned to conventional heat and power if needed.
This is pioneering stuff, widely forgotten since the advent of grid power in the 1950s, and not everybody appreciates the long term benefits of no longer being wholly reliant on grid power.
Recently, the friend of a neighbour, came around to see the engine. Now in his 70's, he told me how his uncle had a Lister engine like my one, back in the 30s, and how, as a young boy, he was allowed to start it. He then explained how in the 1950s, he built a bungalow on a plot of land, and ran a homemade generator set, until eventually the house was connected to the grid. He told me he used the radiator from an Austin 7, mounted on his inside kitchen wall, to warm the house from the engine heat - remember this was before central heating was cheap and commonplace. It just goes to show what goes around, comes around!