What does a kilowatt hour look like? • Hacker News Board

Re: What does a kilowatt hour look like?

#11

Post by freerobby » Thu, Sep 22, 2016, 10:25 PM UTC

qoobaa wrote: post #9

outworlder wrote: post #3

> So, what a kilowatt hour of high-grade electric energy can do for you? According to my car, it lets me drive 4.2 miles at highway speeds.

Interesting, is it Tesla? Which model is it?

As a reference point, a Tesla 85D uses 290 watt-hours to go one EPA rated mile. So 1 kWh takes you 3.448 miles.

Re: What does a kilowatt hour look like?

#12

Post by madengr » Thu, Sep 22, 2016, 10:45 PM UTC

"So, what a kilowatt hour of high-grade electric energy can do for you? Many useful things, i.e.:

deliver 4-5 kWh of low-grade heat (or cold) into your home (depending on COP of a heat pump)"

Huh? I assume he means 0.4 - 0.5 kWh?

Re: What does a kilowatt hour look like?

#13

Post by monochromatic » Thu, Sep 22, 2016, 10:49 PM UTC

madengr wrote: post #12

"So, what a kilowatt hour of high-grade electric energy can do for you? Many useful things, i.e.: deliver 4-5 kWh of low-grade heat (or cold) into your home (depending on COP of a heat pump)" Huh? I assume he means 0.4 - 0.5 kWh?

Heat pumps are more efficient than just using a resistive heater.

Re: What does a kilowatt hour look like?

#14

Post by semi-extrinsic » Thu, Sep 22, 2016, 10:51 PM UTC

madengr wrote: post #12

"So, what a kilowatt hour of high-grade electric energy can do for you? Many useful things, i.e.: deliver 4-5 kWh of low-grade heat (or cold) into your home (depending on COP of a heat pump)" Huh? I assume he means 0.4 - 0.5 kWh?

Nope. Heat pumps have a COP > 1. It's quite literally a pump moving heat from a cold place to a warm place. If it takes 1 kWh to pump 3 kWh of heat from outside your house to inside (in winter), you've heated your house by 4 kWh. Note that the electric energy used to drive the pump is transformed into low grade heat, which in this case is useful.

Re: What does a kilowatt hour look like?

#15

Post by TeMPOraL » Thu, Sep 22, 2016, 10:59 PM UTC

soperj wrote: post #2

What.

One kilowat, i.e. one thousand lines of Ruby or JavaScript code.

https://www.destroyallsoftware.com/talks/wat

Re: What does a kilowatt hour look like?

#16

Post by xyzzy123 » Thu, Sep 22, 2016, 11:04 PM UTC

jononor wrote: post #10

1kWh as gasoline is about 1/10 liter. Though one will not get anywhere near that much high-quality electric energy with consumer/small-scale methods.

1kWh as aluminium is about 66g (assuming 15kWh per kilo manufacturing input) or about 4 drink cans.

Re: What does a kilowatt hour look like?

#17

Post by grondilu » Thu, Sep 22, 2016, 11:06 PM UTC

Not related, but I hate this unit. Can't we just talk about Joules?

Re: What does a kilowatt hour look like?

#18

Post by qoobaa » Thu, Sep 22, 2016, 11:12 PM UTC

grondilu wrote: post #17

Not related, but I hate this unit. Can't we just talk about Joules?

It's not pretty,but it's practical. Especially when it comes to electricity - watts and hours are quite easy to work with.

Re: What does a kilowatt hour look like?

#19

Post by mpreda » Thu, Sep 22, 2016, 11:17 PM UTC

1 Wh is about 0.9 kilocalories. So 1kWh is about 100g of butter. The energy expenditure of a human in one day is about 2kWh. 1kWh is about the energy needed to heat 10L of water from 0 deg celsius to 100 deg celsius.

Re: What does a kilowatt hour look like?

#20

Post by robbrown451 » Thu, Sep 22, 2016, 11:18 PM UTC

Less acronyms please. (COP, PV, and even EV)