Hacker News new | past | comments | ask | show | jobs | submit
bschwindHN | parent | next
I only now got around to watching the Technology Connections video on renewable energy, I wish I had seen it sooner. Almost feels like it should be required viewing. I definitely thought there were nastier chemicals/compounds in solar panels and hadn't updated my knowledge on them in decades.

https://www.youtube.com/watch?v=KtQ9nt2ZeGM

mikeweiss | parent | next
I decarbonized my 125 year old home this summer. Cold winters here, using mini split heat pumps now for heat. Previously had oil, and 90 years ago it would have used coal. Love thinking this will be the first winter this house ever had where dirty exhaust wont be going up the chimney to keep it warm.
loading story #50323006
loading story #50323767
darth_avocado | parent | next
I swapped my hvac for an electric heat pump. My energy usage went down. Because electricity is way too expensive and I’m okay sweating a bit in the summers and wearing jackets indoors in the winters.
loading story #50323261
loading story #50323820
abstractspoon | parent | next
Unlikely. We'd just use the leftover energy for new things.
3eb7988a1663 | parent | next
That's not quite what this is about. It is the Primary Energy Fallacy, that if you are to replace eg coal, you need to replicate its original energy content.

If 1kg of coal represents 1000 Wh, your generator loses 1/2 to waste heat, you only generate 500 Wh of usable electricity. Some analyses will state that renewable power has to replace the 1000 Wh of embedded energy within the coal, when it only needs to output 500 Wh.

If you use solar panels and generate 500 Wh directly, you have cut your energy use in half, even though the output has remained the same. An EV has a battery of ~80 kWh, equal to 2-3 gallons of gas, yet it can go a few hundred miles, a 3-4x ratio of efficiency, compared to an ICE.

loading story #50322824
WalterBright | root | parent | next
The battery loses 10% just by charging it.

I figured an EV is worth about 60mpg with a fair comparison to a gas car.

loading story #50323596
bjelkeman-again | root | parent
A good visualisation for this I think are linked. Petrol/diesel use about 20% of the available energy and electric vehicles use about 80-90% for moving the vehicle.

https://yaleclimateconnections.org/2024/01/electric-vehicles...

loading story #50323184
DangitBobby | parent | next
Why? I didn't start using more energy elsewhere when I switched to an EV or electric lawn maintenance tools. You think companies and people are using exactly as much power as available (or they can afford)?
silentkat | root | parent | next
It's a well-known "paradox" known as Jevons Paradox. Given enough efficient use of a resource, overall usage could actually far outpace the efficiency gains. E.g. use of coal got efficient enough that travel via trains using it became possible, which led to way more usage of coal.
loading story #50323018
loading story #50322590
loading story #50322858
loading story #50322229
loading story #50322639
tianji-astrolog | parent
The 'half' figure is mostly primary vs final energy accounting. A heat pump delivers 3-4 kWh of heat per kWh of electricity (COP 300-400%), and an EV turns ~80-90% of stored energy into motion vs ~25-35% for an ICE drivetrain. So electrifying heat and transport shrinks final energy demand even before counting upstream losses (refining, thermal generation - roughly 60% rejected energy in most Sankey diagrams of the current system).

The comment below about electricity prices is the real friction point though. Where time-of-use rates exist, running a heat pump with thermal pre-heating during cheap midday solar hours changes the math entirely - the building itself becomes the battery. I got into tracking my own load against TOU windows and ended up building a small tool for it (energy-iq.app); shifting ~40% of consumption off-peak ended up worth more than any single efficiency upgrade. Electrification halves the energy; rate-aware scheduling is what makes it halve the bill.

loading story #50323054