Re: SRAM or nuvinci electric pedal asssist

Ryan Cousineau wrote:
In article <tcb4l.728$BC4.222@xxxxxxxxxxxxxxxxxxxx>,
Peter Cole <peter_cole@xxxxxxxxxxx> wrote:

Coal is much cheaper. When it comes to electricity generation, hydro & geothermal often beat even coal, wind is close, solar thermal isn't far off.

Yes, but all fail the portability test. Coal is sometimes turned into methanol (and possibly gas or diesel?) but coal-burning don't work great at much below the electrical-powerplant scale.

Modern coal plants are 60% efficient -- that still leaves the problem of pollution (at the plant & at the mines).


This is a bit off-topic, but I ought to point out a few things about all those grid-oriented power-generation techniques you mention.

I don't know much about geothermal, but hydro works beautifully in large-scale operations. The only problem is nobody has the stomach (read: environmentalists throw organized ***-fits) when anyone proposes another flood-and-dam hydro project, such as the many that for so long powered most of British Columbia*. Solar thermal is in its infancy, but may become important. Probably not so much in Canada.

Hydro works pretty well with wind in that hydro generation can be regulated to match demand. While I agree that there isn't much room for hydro expansion for environmental reasons, its effectiveness can be improved by mixing with less controllable sources.

Wind though, is a nice fragment of a power-generation grid, but it has a hard time being more than that. The big problem is that in most places, wind power is available both irregularly and at odds with the highest demand times. It's possible to mitigate that, but as far as I know, the major mitigation tricks involve storing the energy (heat water, pump water uphill, gargantuan batteries, other essentially-undeveloped technologies). It's not a great solution.

It seems pretty straightforward to get to 20-40% electric from wind (see Denmark). It will never be a total solution, but will be an important factor. Fossil fuel & hydro plants can largely balance the output variances.

*British Columbia used to be a net exporter of power, with almost all local power produced via big hydroelectric projects**. But the province has grown, and new projects have not been approved, because there are a lot of people who are opposed to pretty much any large reservoir-type hydro projects.

Worldwide, hydro is around 20% of electricity generation, ~0.7TW, with another 0.2TW or so in development. It probably won't go much higher as a percentage.

Solar photo-voltaic is interesting because, while peaky, the peak more or less coincides with demand peak. Currently, installed system costs are in the $5-10/W range. If you consider that the US uses around 1TW of electricity, and take a 20% duty cycle for PV, you'd need 5TW or at least $25T to go completely solar. Given the current worldwide production of ~5GW/yr, it would take a millennium. Nukes, clean coal, wind, etc., all have roughly similar investment and production hurdles. I think the bottom line is that there's no silver bullet, the best payback right now is probably conservation and judicious and rapid expenditure on R&D. Technologies like e/hybrid-vehicles, cogeneration, passive solar, highly efficient appliances and lighting can reduce fossil fuel consumption without necessarily introducing new energy sources.
.

Loading