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Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by cmccart on Thursday August 11, 2016 @05:50PM (#12271848)
This got me thinking: how much CO2 is emitted by different energy sources in generating 1 kilowatt-hour?

I came across this link: http://blueskymodel.org/kilowatt-hour

Seems like solar is more or less a break even, where nuclear /wind/geothermal/hydro are pure wins, which makes sense I suppose. Could you manufacture enough of these to consume 1 kilowatt-hour without generating more CO2 in the process than they would consume in their lifecycle?

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by sevenless on Thursday August 11, 2016 @05:53PM (#12271865)
I don't see any accounting for the cost of storing nuclear waste, long-term. (Nobody wants to do it; how do you even estimate that?)
Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by teraflop on Thursday August 11, 2016 @08:37PM (#12272773)
That's true, but it's important to remember that the amount of waste produced by nuclear power generation is many, many orders of magnitude smaller than fossil fuels.

Let's say you want to generate 1 megawatt-hour of electricity (roughly enough to power an average American household for a month). With coal power, you get roughly 2,000 pounds of carbon dioxide dumped into the atmosphere. [1] To generate the same amount at a nuclear plant, the waste primarily consists of about 3 grams of spent fuel. [2][3]

(And before anyone jumps on me, I'm not trying to dismiss other renewable options... just trying to put nuclear power in perspective.)

[1]: https://www.eia.gov/tools/faqs/faq.cfm?id=74&t=11 [2]: http://www.nei.org/Knowledge-Center/Nuclear-Statistics/US-Nu... [3]: http://www.nei.org/Knowledge-Center/Nuclear-Statistics/On-Si...

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by imron on Thursday August 11, 2016 @10:48PM (#12273128)
> about 3 grams of spent fuel.

Now multiply that by the number of households, and again by twelve to see the amount you'd need to permanently store each year.

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by eggy on Friday August 12, 2016 @03:35AM (#12273927)
That's probably based upon older reactor designs like everything in the nuclear industry, since regulation had made progress slow-going.

Newer designs, and some others, burn spent fuel. Out of the 3 major nuclear reactor incidents, all were old reactor designs. There are new ones that also cannot meltdown in the common understanding of the term.

Don't forget coal mining releases nuclear radiation, since you are unearthing radioactive minerals. So much so, that you are exposed to more radiation in the vicinity of a coal plant than a nuclear reactor.

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by prawn on Thursday August 11, 2016 @08:13PM (#12272668)
Here in South Australia, the government, royal commission and a citizens' jury are looking very seriously at establishing a long-term, highly secure nuclear waste dump. We have a lot of very remote areas in this state, and I believe they're looking at a spot with clay very deep down that can be used to insulate against geological movement. The facility is being planned to survive for thousands of years.

Here's some info from the royal commission: http://nuclearrc.sa.gov.au/

And from the Citizens' Jury: http://nuclear.yoursay.sa.gov.au/

As I understand it, being paid to store nuclear waste is being viewed as an income stream for the state to backup or replace income from mining operations.

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by bigiain on Thursday August 11, 2016 @08:31PM (#12272747)
I'm always suspicious of things "planned to survive thousands of years". I'll bet politicians in Rome and Sparta big-noted themselves with "projects which'll last thousands of years!" (which they then contracted out to their brother-in-law). So far as I can tell there's not much other than Pyramids which humanity has designed/built that could plausibly claim to have "survived thousands of years", and even those didn't come close to being impregnable enough to be considered "safe" for keeping curious humans away from long half life radioactive trash...
Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by kraftman on Friday August 12, 2016 @04:13AM (#12274048)
The Romans probably aren't the best example to use to make your point considering how many structures they've built that are still standing.
Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by dalke on Friday August 12, 2016 @12:30PM (#12276913)
Though compare the numbers standing to the many, many more which have fallen.

By "still standing" do you include ruins where, say, only part of a wall remains?

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by sevenless on Friday August 12, 2016 @12:57PM (#12277101)
There are Roman structures that remained intact for millennia. I think the main threat to them was people re-using the masonry.

https://en.wikipedia.org/wiki/Pont_du_Gard

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by dalke on Friday August 12, 2016 @01:17PM (#12277234)
Agreed. And Hammam Essalihine/Aquae Flavianae is a Roman bath which is still in use.

Regarding the Pont du Gard, it's intact "due to the importance of its secondary function, as a toll bridge. For centuries the local lords and bishops were responsible for its upkeep, in exchange for the right to levy tolls on travellers using it to cross the river."

I believe bigiain's point is that the structures needed active upkeep to last thousands of years.

Your point is true about people robbing the masonry, but that's closely related to bigiain's comment about "keeping curious humans away from long half life radioactive trash".

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by sevenless on Friday August 12, 2016 @02:01PM (#12277536)
So one solution for active upkeep, is to build radioactive waste repositories into toll bridges...
Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by dalke on Friday August 12, 2016 @02:53PM (#12277911)
LOL! Yes, that could work. The tricky part would be to keep it from being blown up during some battle, like the Mostar Bridge.
Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by prawn on Thursday August 11, 2016 @11:06PM (#12273180)
These things are going to be buried very very deeply in a particular way. I think people would need to be a lot more than just curious.
Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by prawn on Friday August 12, 2016 @02:15AM (#12273665)
I should add that I believe the plan is to do significant work in sealing compartments so anyone looking to wreak havoc would need to breach the facility, get down a significant distance and then work through a huge amount of concrete or clay or whatever it would be.

I think the supply line from port to the facility would be a softer target and is something the jury and stakeholders would be considering in serious detail.

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by unchocked on Thursday August 11, 2016 @06:13PM (#12272010)
It's easy, you take the cost of Yucca mountain depository (which is already sunk, btw), and amortize that over 10,000 years or so.
Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by omegaworks on Thursday August 11, 2016 @07:41PM (#12272515)
So easy!

Watch how it's done: https://www.youtube.com/watch?v=HeVPMzJOFrQ

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by ChuckMcM on Thursday August 11, 2016 @07:01PM (#12272294)
You burn it as fuel[1]. More kilowatts for small (relatively) additional dollars.

[1] http://terrapower.com/pages/technology

Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by cmccart on Thursday August 11, 2016 @06:02PM (#12271935)
Oh, great point, I hadn't even considered that. I'm sure creating all those steel/concrete containers isn't the most CO2 friendly activity. AFAIK most plants store onsite so there's no transportation cost at least.
Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by sdm on Thursday August 11, 2016 @07:40PM (#12272506)
The same goes for Hydro. Both Nuclear and Hydro have signifiant up front green costs.
Re:New “Leaf” Is More Efficient Than Natural Photosynthesis by kevinpet on Thursday August 11, 2016 @08:34PM (#12272759)
I found 1.2lbs, so this process is able to remove about 10% of the production cost.