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From Canberra to Sydney next to a Hydro Electric Project Specialist

Last week I sat next to a real smart Hydro Electricity project manager. I was coming back from talking to a couple of government department people about a couple of projects. He asked me why I knew so much about Hydro and was interested to hear that I was experimenting in home scale mini hydro electricity systems with the idea of using water as a battery storage medium to back up wind and solar energy generation systems.

We quickly got to tin tacks as he explained how important height is in the equation that defines the basic principles of Hydro power generation being:


Or energy available equals the mass of the water times gravity times the height difference between the stored location of the water and the turbine generating the power. To illustrate the importance of height he explained that the Snowy scheme gets about 2.5 megawatt hours from 1 megalitre of water. At that rate an average Australian 22 kilowatt hour per day home would only require 8,800 litres of water (less than a 10,000 litre tank) to run the house all day!

The advantage of the snowy mountain system is that the mass/ water is 800 meters above the power turbines delivering incredible leverage of the mass. By comparison the hoover dam near Vegas Nevada is only 100 meters high with the turbine at the base of the mass. Hoovers dam will be at least 1/8th the effectiveness our own Snowy system...

According to my virtual proof of concept I would need 124000 litres of water to run one day for an average Aussie home at a 3 metre difference between the top and lower tanks with the mini turbine being at the top of the lower tank.

My new friend also explained the importance of big pipes to minimize drag on the inside surface of the pipe. He said it all comes down to the power delivered to the face of the turbine blade. So now the gauntlet is set.. how do I maximize the height factor? That's the next phase to work on.

By the way another thing that came up was the efficiency of big hydro turbines. My friend said that 80-90% efficiency is common place.

Another thing he mentioned is the common practise of hydro/ coal arbitrage. This means that it is a common practise for a Hydro power company to use coal based electricity during off peak times to actually pump water back up to dams to be resold to the grid during peak times at a profit.

This sounded bad for carbon damage and is inefficiently, but it obviously makes money. In closing another tidbit he told me was that Hydro is really great for peak demand type situations such as new years eve or Australia day because hydro turbines can get up to speed and generate full power in as little as 2 minutes!

It's amazing what you can find out on a 26 minute flight.
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