C'mon Zippo, you can do better than such vague comments... which assumption don't you agree with?
I wrote:
"Cars - on average - are only used about 5% of the day when people are driving them. At other times, they are sitting mostly idle."
That "assumption" is based on ABS data for the 12 months ending 30 June 2016 (I chose the 2016 data since the latest 2020 data might be distorted by COVID restrictions). On average km driven per vehicle in Australia was 13,716km (source: https://www.abs.gov.au/AUSSTATS/[email protected]/Lookup/9208.0Main+Features112%20months%20ended%2030%20June%202016?OpenDocument)
that works out to be 37.58km per day. Even if you only allow for business days (i.e. 52 x 5 days/working week - 260 days), that is 52.75km/day.
In city traffic, stopping at crossings and traffic lights. my wild assumption is that you could do the 52.75km in about 5% of a day - i.e. .05 x 24h/day or 1.2hrs.
If cars were not sitting idle for the rest of the time, their driven km would have to be higher.
So, please point out the error in my assumption...
I then added:
"Obviously, if you are driving 12 hrs a day every day, then this does not work for you."
Further highlighting the fact that I m talking about averages... most people in Australia live in major metropolitan areas.
Let me know, if that has changed.
Then comes:
"However, with EV batteries providing 50kWh to 100kWh in storage, some of that storage cold be tapped into to support the grid."
This wild assumption was based on my knowledge of EVs batteries. Looking at this reference, it looks like that assumption was not too unreasonable:
https://ev-database.org/cheatsheet/useable-battery-capacity-electric-car... average useable battery 59.8kWh.
When I wrote:
"Now, if you have a 100kWh battery in your EV and you know your daily commute of 50km uses about 10kWh (roughly speaking), that allows you to sell perhaps 80kWh back to the grid (leaving you a 10kWh safety buffer)."I was using the 100kWh battery as an example to simplify the numbers. So perhaps I was too generous?
Let's take a
Tesla Model 3 Performance as a real-world example. From the above EV-database, you can see that it actually has an energy efficiency of 165Wh/km and a battery capacity of only 76kWh. So to drive the 50km per day requires 165Wh/km x 50km = 8.25kWh.
So I was actually a bit conservative with the energy required to drive 50km.
Leaving twice as much in the battery than what is required for a daily commute - i.e. 16.5kWh.. still leaves you 76kWh - 16.5kWh = 595kWh of spare battery capacity to trade with the grid.
OK, so you can argue that this is still one of the larger battery capacity vehicles. However, given how ICE drivers insist that they need to drive 1,000km on a single charge I am reasonably confident that over the next 5 to 10 years battery capacities are more likely to increase rather than decrease. Perhaps too bold an assumption for you?!?
My next statement, does not include any assumption:
Yes, you could just buy a stand alone battery for your house, but that is extra money you would need to spend, while you already have the EV.It is merely a statement of fact - there are no assumptions in that sentence.
Next comes:
With zero incremental cost, you could be earning money by selling electricity to the grid during peak demand and charge at off-peak rate (or for "free" from your own rooftop solar).
Actually, it is a lot simpler than that. Instead of feeding back into the grid, you can simply charge your vehicle battery during off-peak time and feed directly from the EV back into your household during peak tariff periods - thereby avoiding the need to buy expensive electricity form the grid.
With the Nissan Leaf 2, that is already possible in Australia (see:
https://www.nissan.com.au/about-nissan/news-and-events/news/2020/July/nissan-leaf-to-light-up-australia.html).
So Zippo, please explain where any of my assumptions are unreasonable.
