Relative to various types of generation - As Willard points out, most of the potential "renewables" are intermittant and unpredictable. Several studies have suggested that as unreliable sources that cannot be scheduled increase, the electrical grid becomes unstable and unreliable. They predict that when you reach about 20% of generation with these souces, you have to add expensive and complex storage systems to the electrical grid.

Some renewable proponents have taken issue with this, saying that widely distributed and diverse renewables will not have this problem. However, in the last year Germany has reached about 15% wind generation and found they now have to operate natural gas fired plants in idle mode (spinning reserve) to maintain grid stability.

The bottom line is that you need a significant amount of economical baseload electrical generation and nuclear is the only non-carbon source now proven that can do that. It's not nuclear vs. renewables because they don't do the same things and fill the same needs.

 

Except Hydro and Geothermal. And solar in many locals is very predictable.

 

Final Comment:

Tidal power sounds great and has been used for years, but it has limits. Areas where the tide is huge (50 feet or so) have reservoirs and release the water through turbines. The problem of course, is that the tidal cycle (24 hours and 50 minutes, not 28 days), while predictable cannot be controlled. To get reasonable efficiency, a tidal system will put out power for, at most, 3 or 4 hours a day and that will cycle throughout the whole 24 hours. So you will sometimes get the power at 3 AM whether you want it or not.

The other option is to submerge turbines in the tidal stream that runs in and out of large rivers and bays. This has the advantage of getting two power peaks per day instead of one, but the projects to date have been unreliable and not close to cost effective.

Geothermal works OK if it's close to the surface and you do enough maintenance to keep the equipment clean (major problem). More recent suggestions involving drilling 5 to 10 miles down. A recent geothermal project in Europe drilled, injected the water, and caused a Level 4 or 5 earthquake. Something to think about.

 

The Italians have had a large geothermal site since the 1920's I beleive they use it to run trians.

 

...and 6000' wells seem to work in the California Geysers area. 5-10 miles down seems a little extreme. I expect the payback was not good!

 

KenG — There are two tides a day.

Stan

 

Actually depending on location there can be as many as four two high two low. Either could generate energy.....

However, like all energy sources, nothing ends up being "free". Everyone likes to dream they are... but they aren't.

We used to all tout dams and "free" electricity... found out damming up rivers killed species of fish that could no longer spawn.... I read somewhere that those windmills are responsbile for killing migratory birds (You'd think they turn pretty slow and the birds would dodge but I guess not) so now they don't want them in bird migration areas.

What do you want to bet that whatever mechanism is used to capture tidal energy won't be "free" and will have unforseen effects on our environment and sea life?

Eventually everyone will learn nothing is "free" and there are always costs. Its a matter of weighing them.

 

That depends on where you are. Every coastal area has a diurnal tide (one cycle per day). Many areas, due to constraints that effectively cause a "sloshing" have two tides per day (semi-diurnal). I just did a quick check and found that much of the north Atlantic including the Bay of Fundy are semi-diurnal. So there may be more generation potential than I had thought.

 

 

Hi,

I sense there may be some plug-in hybrid wannabes on this thread. In the interest of helping to make this an everyday reality, I've just created some bumper stickers to promote Plug-In Hybrid Electric Vehicles, (PHEVs), with the profits going to CalCars, (www.calcars.org), the non-profit established to promote these types of vehicles. This includes some stickers specifically designed for Ford Escape Hybrids.

http://www.cafepress.com/pluginwannabe

As bumper stickers go, I think you will find these to be both humorous and tasteful. Essentially they personify the vehicle, portraying it as wanting to become a plug-in hybrid when it grows up in a variety of languages. The stickers also reference a wiki, (http://phev.wikispaces.com/), where Plug-In Wannabes are invited to register and post a picture of themselves, (optionally, with their owner).

The promotional aspect, (beyond the money contributed to CalCars), comes with the links to various websites about plug-in hybrids, so those who may have become interested in the subject based on the bumper sticker may learn more about them.

So please check it out and join with me in helping to promote the benefits of PHEVs.

Thanks, Matt