Kyoto – A Perspective (Part 12)

Posted on Thu 04/17/2008 by

4


HYDROELECTRICITY (Part One)

Hydroelectric power is the forgotten poorer brother of all methods for producing electricity. It suffers from bad press and I’ll get to that in Part Two. Having said that, it deserves serious consideration, but the problem is that no matter what the simple logic is, hydro power will always be ignored, and more importantly, not even considered.

So first thing, then, just how does it work.
Think of a motor boat. The water is stationary, and the propeller blade rotates driving the boat forward.
The opposite occurs here. The water moves causing the propeller to rotate, only the propeller is now so much larger and has many blades all set at a deep angle, and there may be more than one row of blades. This is the turbine itself, just a very large multi bladed propeller, driving the generator.
No fuel to burn water, to convert to steam, to drive the turbine.
Just water flowing at speed over the turbine.
In cases like these, the whole system is mounted vertically, instead of in a horizontal plane like with all other generating systems.
What it is dependent upon is the speed of the water driving the turbine.
Hence the Hydro plants are always at the bottom of river side of the dam wall.
What this does is to provide a ‘head’ so the water can gather pace as it flows down, and the pipe diameter can be varied to further increase the water’s speed.
This type is the most common form of plant for the production of electricity.

Another form of hydro generation is called pumped storage hydroelectricity, which is really interesting in this day and age of reusing things. This system uses an upper water storage facility, and a lower storage facility. A large diameter vertical pipe goes from the upper dam through the mountain in most cases to the lower dam where there is a power plant. This water drives the turbine generating extra electricity during peak power times. Then, after the peak has passed, excess stored power can be used to drive the generator now as a motor turning the turbine blades in the opposite direction, and with the aid of a pump at the top of the head, the water can be pumped back up into the upper dam. These are referred to as Francis Turbines.
So the water is used continuously, and some of the larger facilities can be used constantly to generate power for up to 40 hours, and then recycle the water for further use, again and again.

Ordinary hydro power also has a huge advantage in that, unlike large base load coal or nuclear plants, they can provide base load power, and at the same time be used for peak power times as well.
With the other two methods, the steam has to be produced to increase the speed, either by dramatically increasing coal supply to the boiler or exposing more of the rods in the nuclear unit.
However with hydro power, a valve is opened further at the head allowing more water to rush into the pipe driving the turbine faster, increasing the speed of the generator, and increasing power production.
These units can have the speed run up as quickly as thirty seconds, so the advantages are significant.

It would seem hydro power might be a viable option, so let’s then look at how much supplied power is generated by this method.
The US is a large producer of Hydro Power, but three other countries use this method on a larger scale. Canada is one of those countries. Brazil is another, and yes, you might have guessed, China is the largest producer of Hydro power on the Planet, half as much again as the US.

Look again at the pie chart and you’ll see that the US produces roughly six percent of its power by Hydro, down from almost ten percent in the mid 1990’s. The World average is up around twenty percent.

I would like to point out some hydroelectric plants under construction, and here I’ll just mention the large base load plants, those over 2,000 MW.
There are currently 19 large plants under construction, and fourteen of these are in China. When you take into account the total power produced by each, the top eleven are Chinese.

The number of large Hydro schemes proposed for construction between now and 2015 number 16 , eleven of which are also Chinese. The largest, The Red Sea Dam in the Middle East is still only in planning with no dates yet for commencement of construction of completion.

So, while the Chinese are producing coal fired plants at the rate of one per week, they are also building large hydro plants as well.

However, in the US, dams with hydro plants are being retired out of commission.

The biggest and most obvious thing about Hydro electric plants is the huge cost of the construction of the dam in the first place, but consider this.

Here in Australia, we have The Snowy Mountains Hydro Scheme, arguably one of the engineering wonders of the World, and still the most complex Hydro scheme on the Planet. Construction was started in 1949, and finally finished in 1974. It consists of 16 major dams hundreds of miles of tunnels through mountains, viaducts, pumping stations and seven Hydro electric power plants. Only 2% of the whole scheme is visible from the surface. It is constructed close to our highest mountain, and the range it is in is only one third as high as your Rocky Mountains. The dams are supplied from snow melt, but here’s the thing. The surrounding mountains are only covered by snow for some months in Winter. As the snow melts, it is captured in dams, and this is what is used to drive the hydro plants, and the water is pumped back around the system to be used again and again. Drought has seen dam levels drop in recent times but the power plants drive on, Guthega since 1954. The water is also used for irrigation for an area covering tens of thousands of square miles, and the huge dams are also used as flood mitigation.
The technology to do something on a scale like this must be there because this Scheme was started in the 1940’s.
In today’s dollars, the cost is calculated to be around $6 Billion dollars.
This is a huge outlay when viewed on the surface only.

However, look at the monster Three Gorges Dam across the Yangtze River in China. It was started in 1994, and is scheduled for completion some time next year.
It will produce 22,500 MW the largest Power plant of any type on Earth, and incidentally generating enough power for nearly half of all Pennsylvania when percentage total power production levels are considered.
The end cost of construction is around 35 Billion dollars in US figures, a monumentally huge amount of money. It has been calculated that the amount recovered from the consumers of the electricity alone will see that full amount recouped within eight years.

So, the cost of construction now does not seem all that much.
No fossil fuels are burnt, and no greenhouse gases are produced whatsoever.
The water can be stored to mitigate flood damage, assist with irrigation for surrounding primary producers and used for the production of electricity.
After construction costs are recouped, electricity produced by the hydro electric method is the cheapest of all forms of electricity, and I’ll repeat that. The cheapest of all.

There is however, bad news about hydro, mainly stemming from the environmental lobby themselves, and I’ll go into that in my second piece on Hydro power.

KPPSTony