←back to thread

160 points riordan | 1 comments | | HN request time: 0s | source
Show context
hodgehog11 ◴[] No.45954362[source]
I've always been curious why a cost-effective widespread implementation of geothermal energy has never been considered a holy grail of energy production, at least not in the public debate. Much of the discussion is so focussed on nuclear fusion, which seems so much harder and less likely to be reliable.
replies(11): >>45954476 #>>45954489 #>>45954493 #>>45954510 #>>45954566 #>>45954710 #>>45954804 #>>45955903 #>>45956518 #>>45957024 #>>45959700 #
roadside_picnic ◴[] No.45957024[source]
> a holy grail of energy production

Since you're comparing it to nuclear, I'm assuming you mean electricity production here, not energy production?

It's always worth remembering that electricity only accounts for ~20% of global energy consumption (in the US it's closer to 33%).

I suspect people confuse these two because in a residential context electricity plays a huge part of our energy usage, but as a whole it's a smaller part of total energy usage than most people imagine.

But any serious discussion of renewable energy should be careful not to make this very significant error.

The Lawrence Livermore National Laboratory publishes a great diagram of US energy use: https://flowcharts.llnl.gov/sites/flowcharts/files/2024-12/e...

replies(2): >>45957833 #>>45958338 #
jimbokun ◴[] No.45957833[source]
What does "Rejected Energy" mean in that graph?

Great chart, by the way.

replies(4): >>45957894 #>>45957982 #>>45958015 #>>45959424 #
1. philipkglass ◴[] No.45957894[source]
Rejected energy means energy that is lost as waste heat without performing any work first. For example, a coal fired power plant may generate 3 megajoules of thermal energy from coal combustion but only deliver 1 megajoule of it as electricity. The other 2 megajoules are lost as useless waste heat.

The 1 megajoule of useful electricity is also ultimately dissipated as low grade heat, but it can do work first (like generating light, or pumping water uphill).