4 ms·

I'm no electrical engineer, but I think we can do some napkin math. 80khw battery in an average model s * 300000000 million cars / (3,911,000,000,000 kwh energ

by mrep 8y ago

I'm no electrical engineer, but I think we can do some napkin math. 80khw battery in an average model s * 300000000 million cars / (3,911,000,000,000 kwh energy use in the in all of 2015 [2] / 365 days per year) = 2.239 times as much storage in cars on the road versus energy usage which seems pretty doable. Also, it also gets better because as car batteries age and their storage / weight goes down, you can replace them with new ones and put the old ones in grid storage locations where weight / storage does not matter and run them till they are literally dead. [1]: about a little less than 1 per person (just rough estimating here) [2]: https://en.wikipedia.org/wiki/List_of_countries_by_electricity_consumption https://en.wikipedia.org/wiki/List_of_countries_by_electrici...

mrep 8y ago
2 big variables I forgot about. 1. We need to eventually switch our winter gas heaters to electric which while helping balance summer vs winter electric usage, electric heating isn't as efficient and we have to increase the outside air a lot more in the winter than we have to cool it in the summer (for most people at least). 2. I forgot to add in the extra electric demand needed to power the cars which is currently powered by oil.
- icebraining 8y ago
  Electric heat pumps are quite efficient, AFAIK.
  - mrep 8y ago
    I heard that a long time ago and thinking back on it, I think it was due to the fact that most electricity comes from burning other stuff so the overall efficiency of burning something to make electricity (definitely not 100%), then transporting over lines to your house, then converting that into heat to warm your home is less efficient than just burning it at your house and using the heat directly.
  - amluto 8y ago
    For swimming pools, which are admittedly a special case, heat pumps are already cheaper to operate than gas heaters in most of the country. (They’re special for several reasons. A big one is that they have huge thermal mass, so your heat pump can operate at whatever time of day you want. This means you can optimize for electric rates vs outdoor temperature. Heat pumps, unlike gas boilers, are considerably more efficient when it’s warm out.)
- Retric 8y ago
  Many things in a home produce 'waste' heat (TV, people, pets, etc) which needs to be cooled in the summer but it is useful in the winter. Further, AC's end up condensing moisture from the air which takes crazy amounts of energy. So, heat pump efficiency vs temperature only tells part of the story. With good insulation you will almost always need more cooling in the summer than heating in the winter outside of the arctic circle.
- jdietrich 8y ago
  >electric heating isn't as efficient Ground source heat pumps have a typical efficiency of about 400%. You're moving heat from the ground to your house rather than heating up the air, so you get considerably more useful energy out of the system than you put in. https://en.wikipedia.org/wiki/Geothermal_heat_pump https://en.wikipedia.org/wiki/Geothermal_heat_pump
- radicalbyte 8y ago
  Heating water with electricity is three times more expensive than heating it with gas in my market (The Netherlands). That turns a monthly bill of 60 EUR for gas warming into a bill of 180 EUR if you just switch like-for-like. A 3:1 ratio. Ground heat-pumps are being championed as a cost effective replacement for keeping houses warm. They provide a 4:1 heat:electricity ratio so have lower running costs than gas. They can also be attached to sun panels and can work with storage heaters (heat the water when the sun shines, use it when it doesn't). Unfortunately pumps are expensive and very invasive to install in existing houses - you need to dig gardens up to lay the pipes and installation for an average house is about 15-20k EUR ($17k-$23k).

by mrep 8y ago

mrep 8y ago

2 big variables I forgot about. 1. We need to eventually switch our winter gas heaters to electric which while helping balance summer vs winter electric usage, electric heating isn't as efficient and we have to increase the outside air a lot more in the winter than we have to cool it in the summer (for most people at least). 2. I forgot to add in the extra electric demand needed to power the cars which is currently powered by oil.

icebraining 8y ago
Electric heat pumps are quite efficient, AFAIK.
- mrep 8y ago
  I heard that a long time ago and thinking back on it, I think it was due to the fact that most electricity comes from burning other stuff so the overall efficiency of burning something to make electricity (definitely not 100%), then transporting over lines to your house, then converting that into heat to warm your home is less efficient than just burning it at your house and using the heat directly.
- amluto 8y ago
  For swimming pools, which are admittedly a special case, heat pumps are already cheaper to operate than gas heaters in most of the country. (They’re special for several reasons. A big one is that they have huge thermal mass, so your heat pump can operate at whatever time of day you want. This means you can optimize for electric rates vs outdoor temperature. Heat pumps, unlike gas boilers, are considerably more efficient when it’s warm out.)
Retric 8y ago
Many things in a home produce 'waste' heat (TV, people, pets, etc) which needs to be cooled in the summer but it is useful in the winter. Further, AC's end up condensing moisture from the air which takes crazy amounts of energy. So, heat pump efficiency vs temperature only tells part of the story. With good insulation you will almost always need more cooling in the summer than heating in the winter outside of the arctic circle.
jdietrich 8y ago
>electric heating isn't as efficient Ground source heat pumps have a typical efficiency of about 400%. You're moving heat from the ground to your house rather than heating up the air, so you get considerably more useful energy out of the system than you put in. https://en.wikipedia.org/wiki/Geothermal_heat_pump https://en.wikipedia.org/wiki/Geothermal_heat_pump
radicalbyte 8y ago
Heating water with electricity is three times more expensive than heating it with gas in my market (The Netherlands). That turns a monthly bill of 60 EUR for gas warming into a bill of 180 EUR if you just switch like-for-like. A 3:1 ratio. Ground heat-pumps are being championed as a cost effective replacement for keeping houses warm. They provide a 4:1 heat:electricity ratio so have lower running costs than gas. They can also be attached to sun panels and can work with storage heaters (heat the water when the sun shines, use it when it doesn't). Unfortunately pumps are expensive and very invasive to install in existing houses - you need to dig gardens up to lay the pipes and installation for an average house is about 15-20k EUR ($17k-$23k).