Energy production, storage, and future technologies

jack_christie

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Three myths about the global energy crisis​


Russia is not winning the battle for supplies nor disrupting efforts on climate change and clean power

 

GRtak

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GRtak

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GRtak

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GRtak

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GRtak

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GRtak

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NecroJoe

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Pretty cool walk-through of a (hopefully) Net-Zero hotel:

I've heard of PEO, but never knew it could be used for whole-room lighting. An interesting stat: the two laundry dryers use more power, when running at the same time, as the whole rest of the hotel combined.

 

Eye-Q

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The german start-up EnerKite claims to produce about twice the amount of energy as conventional wind turbines with kites while being not bound to specific sites (for the smallest version). It sounds like an interesting concept and apparently the trial phases have been successfully finished.
 

calvinhobbes

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I've heard of PEO, but never knew it could be used for whole-room lighting.

I’m sure you’re familiar with the story of the slow recognition of the potential of the electric motor as a replacement for steam engines:


Sometimes I wonder what the present-day equivalents might be and this DC lighting powered “directly” (i.e. without DC/AC conversions) by solar panels and batteries is one of the examples.
 
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jack_christie

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Interesting trial staring in the UK where you can get a free tepeo electric heat store

 

eizbaer

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DC lighting powered “directly” (i.e. without DC/AC conversions) by solar panels and batteries is one of the examples.
there's a pretty big initiative going on at the aachen uni by a few departments that are very much in favor of switching most building electricity demand to DC. everything will be smaller and more efficient that way, in addition to the easier integration of solar, batteries, lights, you name it. however the huge hurdle, as always, is that they're trying to replace an established and accepted system. they're facing the problem that all their tech would, at first, be niche stuff only adopted by very few people, which in turn just makes it expensive. i believe standards aren't even the issue anymore, it's now more cost and ease of replacements and such.

but yeah... it's honestly pretty dumb the way that we keep converting between AC and DC just for the fun of it. at least there's hybrid inverters now that couple battery and PV on a DC basis... but still, then I switch that over to AC, feed it into my wallbox, into the car, which turns it back into DC for the battery. I think since all the conversion steps are all 95%+ efficient, nobody seems to care, but honestly all the small stuff also adds up.

tepeo electric heat store
I saw that thing on fully charged and thought... well, that must be one of the dumbest products i've ever seen. or am i missing something? like it's literally a hot water tank with an immersion heater stuck into it, basically, yeah? so it's not especially efficient (compared to, say, a heat pump) or anything. the only thing it's got going for it is a) it's electric and b) it's probably super cheap to buy. ok i guess i see the appeal, carry on :| still a bit daft to sell that as a great new greentech thing - we've had (tank-less) electric boilers for 60 years and nobody would ever claim they're green or efficient or anything.

edit: PV installations that have shit feed-in-tariffs (say from the late 2010s) here in germany quite often have an electric immersion heater added to the houses hot water storage as well, to dump any excess PV production that isn't self-consumed - since that is more economic than feeding it into the grid. but that is just ditching excess energy to help the main heating system along, not the ONLY system in place.

oh well - gotta hand it to the tepeo folks: great marketing they're doing...
 
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Matt2000

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Offering DC options for lighting and many other items wouldn't be that difficult, with LED lighting it would just mean bypassing some of the rectification. That's often the part that fails and causes the item to be thrown away, so manufacturers might be reluctant to 'extend' the life of their products.

Laptops and such should use a fixed voltage so they can easily be fed by DC, I can't see that happening unless regulations are put in place though. I'm not sure what the voltage would be, if it was 12V I imagine lots of companies would get upset that they lose the sales of 12V travel adapters.
 

eizbaer

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Offering DC options for lighting and many other items wouldn't be that difficult, with LED lighting it would just mean bypassing some of the rectification. That's often the part that fails and causes the item to be thrown away, so manufacturers might be reluctant to 'extend' the life of their products.

Laptops and such should use a fixed voltage so they can easily be fed by DC, I can't see that happening unless regulations are put in place though. I'm not sure what the voltage would be, if it was 12V I imagine lots of companies would get upset that they lose the sales of 12V travel adapters.
that's the thing - all the stuff IS ALREADY DC ANYWAY, you just have to ditch the conversion part. and yeah, you're probably right about that being the limiting factor regarding device lifetime.
I'd actually argue the same is already true for any USB-C power delivery brick: behind the AC/DC conversion (fixed voltage) it already does the voltage regulation DC-DC anyway to supply any device plugged in with whatever it requests.

point being: from a purely technical standpoint it'd probably be the easiest thing in the world - actually much simpler than whatever the crap is going on today.
 

GRtak

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The whole reason we use AC is to transmit it farther than DC is capable of being transmitted.
 

Matt2000

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The whole reason we use AC is to transmit it farther than DC is capable of being transmitted.
Indeed, but we're talking about using power that is stored or generated locally in DC form. Externally generated power would still need to be AC, you could potentially just have a bigger, highly efficient rectifier alongside your electricity meter though.

Another advantage is safety, if you ran a house from DC it would be safer. It isn't alternating at a frequency so doesn't cause as severe muscle contractions if you happen to put yourself in the circuit. Oh, I almost forgot that once you eliminate AC in the house you also eliminate the silly 50Hz/60Hz problems with appliances.
 

eizbaer

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Matt2000

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:unsure::unsure::unsure:
https://en.wikipedia.org/wiki/High-voltage_direct_current#Advantages that seems to contradict that. also the disadvantages listed seem in large part to be based in the fact that the existing grid is AC, rather than DC (so not a fundamental disadvantage, rather a systemic one).
The equipment to deal with DC at high voltages is very different to AC as it has to deal with arcing much more. As per the article, AC crosses 0 volts at every cycle so it will stop arcing, DC won't. It's a very costly change and it looks like efficient breakers have only been produced in the last 10 years.
 

narf

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Another advantage is safety, if you ran a house from DC it would be safer. It isn't alternating at a frequency so doesn't cause as severe muscle contractions if you happen to put yourself in the circuit. Oh, I almost forgot that once you eliminate AC in the house you also eliminate the silly 50Hz/60Hz problems with appliances.
The key safety aspect of something like PoE is 48V, not DC. No great transmission efficiency for high currents, but who needs that for in-house LEDs :dunno:
 
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