How can I generate free energy?
The three obvious sources are solar panels, wind generator and a towing generator – that is a propeller in the water that is driven by the speed of boat when its sailing.
Another possibility is a fuel cell. I thought such things were only used by NASA to power spacecraft but there are now commercial models available, but expensive, low output, and require a fuel source such as methanol.
In my case, instead of a towing generator I had hoped I could use the electric motor that will provide propulsion for the boat. There is no difference between a motor and a generator, and so, when the motor is driven it will generate power. When sailing, if I leave the motor in the water it should generate power to recharge the batteries.
Solar Panels
Current Sunshine already has 6 solar panels permanently mounted – each produces 40 watts of power under ideal conditions. Since I bought the boat, she has been running almost entirely on power from the solar panels. And on sunny and partly cloudy days this is enough for my domestic needs.
But on days when I go sailing there is additional power consumption from navigation equipment – depth sounder, GPS, auto pilot, navigation lights, radio and so on – and on these days there is often not enough power from the solar panels to provide for this extra load. So after sailing it could take a few sunny days to recharge the batteries.
And when I get three or four days of continuous cloud cover there is very little power available from the sun. And on the worst of these days I’ve needed to connect to the grid and top up my batteries.
With an electric drive motor as well, you can see I would have a power deficit. I have added another Solara solar panel, and two Unisolar flexible panels. These are all unmounted and can be moved to the best position to catch the sun. After coming into an anchorage under power, the batteries will be down, and so over the following days they will get topped up by this excess power. But on cloudy days I still need another source of power – and I won’t be connected to the grid.
If you’d like to see actual data on how this is working out in practise here is a chart of the status of engine batteries, and motor use.
Wind Turbine
When I was at Scarborough boat harbour tied up on the marina it was a good chance to check out wind turbines. Many of the yachts around me have wind generators and when there’s 20 knots of wind they are spinning their heads off. On cloudy rainy days, there’s no sun, but lots of wind. So having both a wind generator and solar panels makes a good hybrid system. On days when there’s no sun, there’s more than likely some wind.
The boat harbour is a good place to look at wind generators – there’s plenty of them, and lots of different types. Easily the most popular are the AirX three bladed generators – with props that look like they belong on an aeroplane. On days when there’s not much wind these are all still – perfectly still – generating no amps. And yet there’s some Rutland generators, and other types, that are spinning nicely. These that run in low wind speeds have six bladed props. So which type is best?
My plan is to rely mostly on solar power, and power from re-gen when sailing. And only when at anchor would I use the wind generator by hanging it in the rigging. So I would only ever use the wind generator when riding at anchor – and the place I would choose to anchor is in the lee of an island or headland, deliberately getting out of the wind. So chances are the wind at anchor would be light and turbulent, even if the prevailing wind is strong. So clearly its important for me to have a wind generator that’s efficient at low wind speed, and works well in turbulent air.
For many other yachties who would have their wind generator permanently mounted, and therefore would be using it a lot at sea, in clear air, they may choose differently.
The common turbine that performs best at low wind speeds and in turbulent winds is the Rutland 913. Its not as good as the Air-X above 14 knots – but even then its producing good power. Below that, it would often be double the Air-X. And in some comparative tests done by Sailing Today, the Rutland produced the most power over a multi day test, because its still working in low and turbulent winds. In turbulent winds, the Rutland keeps spinning when the AirX has stopped – and it takes a gust to get it started again.
But the best one I found for low speed power is the Four Winds II which is not common here in Australia. It starts in winds speed around 4 or 5 knots and at 8 to 10 knots will produce 40 to 60 watts. This is well above the others, and in old multi day test results from the web, it outperformed the rest. It has another advantage for me, and that is that it is two bladed and therefore easy to stow.
So I imported one of these and its proving to be pretty good but I don’t have a lot of experience with it yet. This would have to be the world’s ugliest wind generator. Its very agricultural.
The rig I made for it failed, and I haven’t gotten around to making a new one yet.
Towing Generator
To begin with when I had the Epod motor I didn’t need a towing generator because the Eopd had regen capability. But not very good and nowhere near what was promoted by the manufacturer. It didn’t produce useful power until the boat was sailing faster than 7 knots. And even on this fast boat that doesn’t happen on low wind days.
The Torqeedo doesn’t have the capability of regen, and so I plan to use the dynamo of the Four Winds II as a towing generator.