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Nuclear

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jerry1423

Mechanical
Aug 19, 2005
3,428
If I was younger and contemplating what career direction to take I would consider nuclear engineering.
After the windmills are built and the solar panels are installed we are going to need to build something to supply us with constant energy.
Since very few people of this generation entered this field there will be a high demand for them in the coming years. It may be 10 years in the future, but it will come.
 
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Hello,

Nuclear energy is the ONLY serious alternative that we have to oil. However, its not enough to keep us from becoming a third world everywhere.......

The readily extractable oil, coal and gas (‘hydro-carbons’ or ‘fossil fuels’) on our planet are nearly completely exhausted.

When oil has gone, our wealth will go with it.

Deep lying hydrocarbon deposits remain. However, the extraction of this hydrocarbon is futile, since the energy expended in its extraction would simply be greater than the energy given up by the hydrocarbon, in doing useful work. (eg powering electric generators and/or combustion engines etc etc)

Since solar and wind are intermittent, they cannot alone fulfill our energy needs.
It is also worth noting that solar and wind only supply electrical energy, they cannot be used to power internal combustion engines (unlike oil).

To take benefit of solar and wind, the electricity must be put into an electricity grid network, or stored in batteries.

Nuclear energy is the ONLY alternative that we have to oil.

However, when fossil fuels are gone, Nuclear Power won’t be able to power our society. It is simply too inflexible. The fact is that there are so many essential processes that require oil.

-Oil has the great advantage that it is easily transport-able and can be used to power internal combustion engines, and can produce electricity anywhere, (eg in off-grid locations) since it can be used to power remote , mobile electricity generators. Oil also gives us a large amount of energy for a relatively small volume of oil.

Think of a construction site where large buildings/structures/bridges/mine-shafts/tunnels are being constructed………..
…Such sites require large earth moving machines, diggers, mobile cranes & hoists, pile drivers, earth drills….not to mention that the building materials need to be transported to the construction site
…..how will these things be powered by nuclear power?……………they won’t….its simply not possible on a scale big enough for the requirements of our vastly populated earth.

We might try to use battery powered diggers and cranes etc…………but there simply isn’t enough of the chemicals which are needed to make batteries to be found on earth to allow us to produce enough batteries for our needs.

Not only that, -but how are we going to mine these rare battery chemicals when there is no oil to power the digging machinery in the mines?
Remember, the chemicals we need to make batteries aren’t conveniently located in parts of the earth where the electricity grid exists to power digging machines………….even if it did……are we really saying that our digging apparatus would be practical with a huge electricity cable connected up to it?

Also, the energy that’s needed to manufacture a battery and keep charging it back up as it discharges is enormous….something like 300 times the energy that the battery ever gives to us in its lifetime doing useful work.

Then there’s transportation (cars, lorries, boats and aeroplanes)
……Will we be able to power all these by battery?

The answer is no…….. As stated above , there simply isn’t enough battery chemical in the earth to make enough batteries for our needs……….even if there was, we would need oil to help us to mine it (dig it out).

Hydrogen has been put forward as an alternative to gasoline in cars. But a fuel supply lorry transporting hydrogen from west side of the USA to the east would have to use all its stored hydrogen in doing the journey….none being left to supply there-after.

Take a country like UK just for example. The UK hasn’t got enough arable land to be able to provide food for its population. We rely on vast transportation to bring foodstuffs in from abroad. –This will no longer be possible when oil has run out.

In the agricultural world, its known that agriculture is the act of using land to turn fossil-fuel into food, -such is its all-round, complete dependency on fossil fuel.
When oil runs out, we won’t be able to get enough food to eat.

Think of a huge wind farm. Unfortunately those huge turbines impose a significant mechanical stress on the bearings and the wind-turbine eventually needs replacement of large parts. –How will this maintenance be done when we have no oil?………..with extreme difficulty……….cranes would be needed to hoist the heavy equipment up to the top of the tower, and its already been stated that powering all the cranes that we need with batteries is impracticable.

Another point is how will wars be fought when we have no oil?

Tanks, Jets, Battleships, Troop transporters need oil to power them…….Batteries just won’t be practical in a war for powering tanks and the like……what sort of battery would be needed to run a tank?………..it would be enormous, would be far too heavy, and when it ran out , we likely wouldn’t be able to get the tank back to a re-charging place.

Life anything like we know it without oil is simply not possible. There will be a severe drop in wealth all round. That’s why the world’s navys have been towing mile long sonar arrays around the world’s oceans for the last twenty years…-to see if there are any oil-likely sites in sub-sea locations………..however, there have not been reports of significant findings.
 
treez - you sure we're about to run out of coal? Most estimates I see claim places like the US & UK have something like 200 years of coal left.

Of course some of that may be deep pit coal (you know, the industry that is all but extinct in the UK thanks to the last few wonderfull governments) but it's there, and the technology to extract it is proven.

Most of the 'alternative' energies are probably best suited to making electricity, even coal for that matter.

Oil & Gas, in their various processed forms, are indeed useful commodities for which there aren't obvious realistic replacements at present.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies: What is Engineering anyway: faq1088-1484
 
With enough electricity, we can synthesize all the fuel we want. To me, that is what makes nuclear so attractive.

As more of the world goes nuclear, we will discover how precious and limited useable and accessible nuclear fuel really is.

Fusion is still a pipe dream. Fission evolved quickly from experiment to weapon to power source to industry. Fusion is stalled. Still, it's a great dream, one worth pursuing.

That's one reason why projects like CERN are so important. These bleeding edge experiments could yield new knowledge that could get us closer to abundant clean energy.
 
Nuclear has a small bad problem, it is not very easy to ramp or follow loads with a nucular unit. That is one of the reasons they are used as base load units.

Coal has somewhat of a simular problem in that it dosen't ramp up and down very well. So they are used just above the base load of the nuclear units.

Gas, oil, hydro units usually are much better at ramping up and down to follow the load, and are used as such. But there is a limited amounted of hydro, and you are saying we are running out of gas and oil.

How about we make bio-gas and continue with the technologys we have until a more workable solution comes along.
Hydrogen can be part of that, but is much harder to store, than methane.

Interesting enough, partial burning of wood or coal will produce a gas that can be used in a gas turban, which has a fast enough ramp speed for load following.

Another option is time of use rates to encurage better load smoothing which would make nuclear a better option than it is now.
 
Of course, coal (and some other materials) can be processed into various equivalents of gasoline, natural gas, kerosene, diesal etc. However, it's the efficeincy that hurts it.


KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies: What is Engineering anyway: faq1088-1484
 
One of my favorite quotes:

"The most striking thing about modern industry is that it requires so much and accomplishes so little. Modern industry seems to be inefficient to a degree that surpasses one's ordinary powers of imagination. Its inefficiency therefore remains unnoticed."

Can anyone guess who?
 
IceNine, I can't identify, but I will name a few likely candidates:

Jeremy Rifkin
Amory Lovins
Algore
?
 
I'll google for it but it is far too literate to be a modern politician or meeja junkie (tautology there).

I'm guessing Edison.

Well, that was a bad guess. The actual writer hasn't really had much influence on things.




Cheers

Greg Locock

SIG:please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
 
Just a couple of points, as I am no energy expert:
1. Nuclear power is a lot more "flexible" if combined with hydro in pumped storage projects.
2. Really big "digging machines" (draglines) are already powered by huge power cables. Not very mobile, but they dig out a lot of stuff before having to be moved.
 
The problem with using pumped hydro to make Nuclear more flexable, is the wind power people are wanting to do the same thing. There just isen't enough pumped hydro available.
And no one has made a commitment to building very much more.

I suspect pumped hydro of larger sizes would be almost the same size undertaking as the Nuclear plants themselves. Not in technology, but in aquiring the usable land to do this. And the time it takes to build it.
 
re pumped hydro - Let's guess that the pumping system is 75% efficient (say 80% impeller, 95% motor/generator and electronics). That means the pumped energy is only 56% of what you started with. In the LEV game we call this friction, it is why a Prius only posts respectable mpg, compared with a conventional car of the same performance and capacity. It is also why the optimal cruising speed of a solar car is a band rather than a fixed figure - if the sun shines a little brighter it is worth increasing your speed rather than taking the losses involved in putting the energy into the battery and back out again.




Cheers

Greg Locock

SIG:please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
 
As stated in other threads, there are other methods to store electrical energy. All have a 50% to 75% range which must be figured into $ costs.

I still feel time of use rates, and education will acheve some usage shifting, which is probally better than the storage thing. But it won't completly erase the need for storage of peaking generation.

 
Are nuclear power plants really that bad at following the load, or were they just built that way because it was the cheapest and all the other guys could handle the load swings anyway. What do they do in France which I believe has 80% or more nuclear power? Maybe Germany, Switzerland, and Spain handle the swings for them?

HAZOP at
 
Steam plants in general are not that great at following load swings. They can do it, but they suffer added problems and costs (parts changing size with tempeture shifts, etc.). And sutting one down daily is even worse.
Gas turbans suffer the same issues, but the fuel costs to keep them running tend to outweigh the re-start up costs.

From what I've seen hydro units seem to suffer the least from re-starts, but typical of some hydro units is the 8 hour shuit down time for them to come to rest.

IC engines probally are not to bad on re-start costs, but they suffer from a size issue to date.
 
larger load generation variations are to be expected with the increase in wind and solar renewable resources. For example, in the ERCOT region (Texas)in Feb 07 there was an uncontrolled loss of 1500 MWe in 2 hrs due to a large wind farm overspeed event- once the wind speed exceeds 50 mph, the wind turbine shuts off, and all units in the same geographical area shut down at the same time as the wind exceeded 50 mph. This forced the isolated ERCOT grid to rapidly bring online whatever capacity is available to offset this loss.

The the double whammy occurred- as the wind speed dropped to an allowable 50- mph, the turbines re-loaded , which caused too much capacity to be available- and this event may be the poster child for distribution system instability when using renewable resources. ( A similar event occurred in Europe a year earlier).

Europe has a lot of VP coal-fired once thru subcritical boilers which can change load very quickly- about 5% / minute,and they may be able to address the system disturbance better than the installed systems in the US. Also, their method of heating homes ( radiant heating installed in concrete or ceramic tiled floors)has a long time constant, suitable for allowing "smart meters" to trip those consumers temporarily to offset loss of power generation- not so in the US. The US mostly uses constant pressure drum type boilers, limited to about a 1.5% /minute rate of change of load, and most home consumers use forced air heating, much less suitable for reduction of system consumption due to a loss of generation .
 
I am not an expert on transportaion, nor would I say I'm very knowledgable in the energy/power fields...

However, one thing that struck me about what treez said was all the equipment that couldn't run on nuclear power. What about nuclear submarines? Couldn't a tank, airplane, etc be built on the same principles? Or does the sub use seawater for cooling which would not be as readily available for land/air use?

-- MechEng2005
 
Or does the sub use seawater for cooling which would not be as readily available for land/air use?

Ding! Give the man 100 points.
 
Also size, mass/weight & what happens in the event of a crash (or similar) are major factors. Good reasons why nuclear powered aircraft aren't generally considered a good idea, despite significant research including a flying test bed.

KENAT,

Have you reminded yourself of faq731-376 recently, or taken a look at posting policies: What is Engineering anyway: faq1088-1484
 
I really don't think the sea water cooling is a requirment for nuclear power. I think a bigger issue is the masses required for shielding, and cooling equipment. An open fluid flow like sea water helps.

The almost 8 ft of concreate around most nuclear power reactors is probally the bigest limit to nuclear airplaines. Of course if you had no concerns for people, you woulden't need all that mass. Also steam plants don't do very well at moving air, unless you have large props.

Transportation fuel is a tough issue, but it looks like the best way to use nucular for this is nucular ships, and electric trains.
 
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