UUUUUUUUURG. Electric Vehicles

Originally Posted by yorkie_chris

That was my point, it's never going to be efficient. But if it's done with solar heat then that doesn't really matter.

That's it, they can just use the sun to create the required temperature like setting light to a bit of paper with a magnifying glass

Originally Posted by yorkie_chris

That was my point, it's never going to be efficient. But if it's done with solar heat then that doesn't really matter.

Exactly. Its an energy that should be there every day and if it isnt then... well we are screwed

Originally Posted by at-sv

That's it, they can just use the sun to create the required temperature like setting light to a bit of paper with a magnifying glass

Welllllll. They did actually use their machine to melt steel and OMG it went through it in seconds. MENTAL!!! Also incinerated a hot dog as well. ha ha.

They also mentioned that they had worked on a system that used a reletivly much lower temp to do the same job. If this is right then it will be much easier im sure.

[yorkie_chris]

Is going to need a massive energy input too though, not just temperature, heat.

Roughly 45MJ/kg at total efficiency. Roughly 300W/m2 from sunlight in a really really hot desert, some sums give that as roughly 41 hours to produce 1kg of petrol from 1m2 of ground.

[yorkie_chris]

Doing it at a lower temperature will be easier, as you can use lower quality heat to do same job, but still needs the massive amount of heat transfer.

Originally Posted by yorkie_chris

Is going to need a massive energy input too though, not just temperature, heat.

Roughly 45MJ/kg at total efficiency. Roughly 300W/m2 from sunlight in a really really hot desert, some sums give that as roughly 41 hours to produce 1kg of petrol from 1m2 of ground.

Oh yes i think the mirrors they used were large... about maybe 4-6M diameter, not sure as it didnt really show very well. Luckily for this there is no limit of desert really. A good use for it is this

[yorkie_chris]

OK so lets fudge it a bit. Say it was 48 hours per kg ... so .5kg/daym2

A random statistic gives up petrol consumption as 72 million liters a day. So at 0.369l/day-m2. That's 195 million square meters of mirror. Just for the UK's fuel use. Lotta desert that.

Edit: 72 million liters is 5.3x10^7kg. 2.34x10^15J of energy a day, equivalent to 2.7x10^10W. That's nearly 7 chernobyls worth of power output. Just for petrol.

Aye... but they said something about 4-5Gallons (US) which is more like 8-9KG's over 24 hours... So maybe they do require considerably less power than you think?

[yorkie_chris]

6m dia. mirror is 28m2. 15 kilos of fuel a day roughly by my guesstimates. 19.3 liters ish. 4 gallons ish.

If anything that confirms my bodge-maths.

Edit: Bugger... misread the post ... but yes would make more sense. Just take that to mean they're getting 60% efficiency at a guess...