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Old 11-26-2006, 08:51 PM   #1
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Large scale energy efficiency (video)

While i am not the biggest beliver that global warming will kill us all in 100 years I found this video very interesting. It talks about energy efficient powerplants in denmark and sweden. If you have some free time sit back and enjoy the video.

2008 EPA adjusted:

Distance traveled by bicycle in 2007= 1,830ish miles
Average commute speed=25mph (yes, that's in a car)
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Old 11-27-2006, 10:51 AM   #2
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Interesting vid.

Message seems to be: don't waste the "waste" heat; follow a decentralized rather than monolithic centralized generation scheme and we could recover enough energy (improve efficiency) that we won't have to build additional power plants (specifically, nuke plants - a Greenpeace sore spot).

It seems that energy issues are mostly political questions. The technology for stable alternative approaches is already here.

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Old 12-05-2006, 06:39 PM   #3
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Originally Posted by MetroMPG
Message seems to be: don't waste the "waste" heat;
Exactly. If you usefully use the "waste heat", you will (hopefully) avoid having to spend some of the generated energy to heat things.

Also, you forgot about not wasting the CO2. Plants (the growing type) really like CO2, and tend to absorb it to grow better. So by sending the CO2 to a "greenhouse", you both help the plants grow, and clean the waste gasses of some CO2 (lowering the so called "greenhouse gasses" being released into the air)...

NOTE: One "gotcha" with such a setup, is that you do have to create a system for piping in (and billing for?) heat produced by plants. There are clearly systems to do this (heating some liquid and moving it with pipes, for example). But for areas that aren't used to piping heat around, it is a lot of infrastructure to build the first time...

Originally Posted by MetroMPG
follow a decentralized rather than monolithic centralized generation scheme and we could recover enough energy (improve efficiency) that we won't have to build additional power plants
The VID really didn't go into WHY a "decentralized" system was more efficient, so I'll take a stab at it.

A decentralized system can be more efficient, as it can help avoid "transmission losses". Simply put, the further you have to pipe power, the more losses you will have in the transmission lines. So by keeping the distance the electricity move down, you save power. And this is doubly true of piping heat, as heat piping technology have much higher "transmission losses" over distance than electrical transmission. So if you want to effectively use the "waste heat", you really have to be "close enough" or your losses will make the whole exercise pointless...

Now, that said, the VID was clearly one-sided on this issue, because they failed to mention the other side of the coin. Specifically, while decentralization has lower overall transmission loss (along with "redundancy", by being able to take advantage of your neighboring plant when yours is down or unable to handle the load), not all the advantages lie with decentralization. One key advantage on the other side (i.e. on the side of "centralization") is "economy of scale". Specifically, many technologies (including many energy technologies) are naturally more efficient the larger you build. And when you build smaller (in order to decentralize) you lose some of that "economy of scale" advantage. It might very well be that the advantages of decentralization outweigh the advantages of centralization, but the point is that both have their own plusses and minus (and the VID made it appear that all the advantages lie with decentralization, which is untrue)...

Originally Posted by MetroMPG
It seems that energy issues are mostly political questions. The technology for stable alternative approaches is already here.
In many ways, yes.

But it's also about the real work of changing the infrastructure, when that's appropriate. Let's face it, there is a lot of work/expense with digging up streets to put in new utility pipes/lines that were never there before. And in order to use "waste heat" (or waste CO2, or reuse "gray water", or...) you need to build an infrastructure to support it.

For example, one fairly efficient way to move around "waste heat" is a closed loop liquid pipe system. In such a system, the "waste heat" would warm some liquid which is then piped to where the heat is needed. When the heat is removed (at the destination), the (now colder) liquid is sent to a return pipe. Conversely, someone who needed "cold" would pull from the colder "return pipe", and put their heat into the main "hot" pipe. The idea with such a system, is that both heat and cold are piped around in liquid form. Such a system not only adapts itself well to using "waste heat", but it is even more efficient than that because one building can get "cold" and another "hot" from essentially the same pool of energy (because you are just moving heat around).

A University I know of, has such a system for most "on campus" buildings, and it works real well in many ways. BUT, there was a lot of upfront expense, because they had to: 1) Dig up the streets to put in all the "hot" and "cold" piping (along with proper return piping) between the buildings (and make sure those hot and cold pipes were decently insolated, so they didn't lose their hot/cold into the ground). 2) Make sure this "hot" and "cold" piping was in the buildings, so that parts of them that needed hot/cold could get it. 3) Modify many of the systems that required "hot" and/or "cold" to work with the liquid piping (for example, having "air conditioners" that pulled from the "cold" pipe), 4) And even have some expense for backup (more traditional "electric") devices for if/when the hot/cold piping was down and you couldn't afford to have your "hot" and/or "cold" to be down (for example, a computer room may have the main cooling via the pipe system, but a backup electric AC for when the main system is down). The University was willing to go to this HUGE upfront hassle/expense, because of the long term benefits of such a system. But what about a city (for the building to building pipes) and individual home owners (for all the piping and use within their buildings)? Given all the "upfront expenses" (when you already have a "working system" in place), I suspect that it would be a much tougher sell for a city and especially individual homeowners.

And "waste heat" is only one thing that you could (in theory) pipe around. If you get creative enough (and are willing to put enough pipes, or other resource conduits into the ground) there are many areas you can get more "efficient" in. For example, why use fresh potable drinking water for a toilet, when many areas are very limited as to their potable water supply? Wouldn't it make much more sense to keep the potable water for things that need it (such as drinking, washing dishes, etc), and using "gray water" for flushing waste away? After all, it wouldn't be too hard to design a system where the water used for flushing was previously used in the dishwasher (or the bathtub, or). But such a system would also require investments in new "piping", so that you could make a distinction between "clean water", "gray water", and "sewage" (whereas right now we just have either "clean water" or "sewage", and nothing in between).

So IMHO this isn't "all" about politics. Some of it is clearly politics, but some of it is the real hassles/problems of building more "transmission" infrastructure of various types (heat, cold, "gray water", etc). And while such structures cost something even when you are doing new building, they can be very costly to "retrofit" onto a system that was never designed for these types of transmission...
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