This video was made possible by you,
and my Patreon supporters.
Without you, this channel would not be possible.
Thank you!
Last month, Elon Musk unveiled a
curiously anticipated Tesla truck.
A vehicle that most people 
will never step inside or drive.
Yet it was met with hysterical screaming and cheers.
The power of Elon Musk to generate hype for his next project is the envy of CEOs across the world.
So, what is the big deal about a truck,
and why is creating a battery-powered truck 
such an impressive feat?
In the U.S. alone, 
the trucking industry contributes to about
23% of the total greenhouse gas emissions,
equating to 1.475 million metric tons of carbon dioxide.
Converting this industry to renewable energy sources
would be a huge win 
in our battle against climate change.
But this isn't just a matter 
of throwing some batteries in a truck,
adding some motors, and marketing it 
to bejesus using Elon Musk's hyper powers.
There are actual technical issues 
we need to overcome first:
the most prevalent of which 
is the energy density of the batteries,
which is the amount of energy provided 
per kilogram of their own weight.
Vehicles like semi-trucks 
are categorized as Class A vehicles,
bound to a maximum weight of 36 tons 
by the Federal Highway Administration.
This weight includes the weight 
of the truck and payload,
so any increase in the truck weight
will result in a decrease in payload– 
the part that pays the bills.
For an energy source like batteries,
which have a low energy density 
when compared to fossil fuels,
this creates issues when 
attempting to create a vehicle
that will offer a value proposition 
to the trucking industry.
Let's assume our truck, without batteries, 
will weigh about 7 tons.
This is based on current trucks without an engine.
That leaves us 29 tons to play with
to figure out how much 
of our weight to assign to batteries,
and this is where designers need to make a decision:
include more batteries, 
and the truck will have a greater range,
but will be able to carry less payload.
Or create a smaller battery pack, 
which sacrifices range for a greater payload.
A diesel truck can carry over 20 tons 
with a range of 1,500 km, or 900 mi.
We know Tesla will be creating two variants of its truck: 
a 300-mile and a 500-mile variant.
And while Elon hyped the 0-60 acceleration 
that no truck driver is ever going to use
unless they want to be fired 
the moment they arrive at the depot,
they left out the one crucial bit of information 
everyone in the trucking industry was waiting for:
the weight of the empty truck, which will determine
exactly how much cargo the truck can carry,
and thus how quickly a buyer 
will get a return on investment.
I found the purposeful secrecy 
behind this information incredibly suspicious,
but it may just be a case 
of Elon wanting to wait another 2-3 years,
with possible energy density improvements 
on the horizon, to make that announcement.
The continued improvement of energy density 
was the driver of this new era of electrical vehicles,
and Tesla has been on the vanguard 
of many of the technological advancements,
and it's in their best interest to do so.
There really isn't any proprietary technology in Tesla that someone like BMW or Ford couldn't copy,
and quite frankly, improve upon.
Tesla, without their own battery production,
is really just a very well-marketed brand.
So let's calculate the energy these batteries 
will need to provide these two trucks,
and more importantly, how much they will weigh.
To do this, we first need to estimate how much energy
this truck will consume for a given range.
This is relatively easy. 
"Energy" is simply given as "power" by 'time".
We can calculate "time" by dividing the range 
by the average speed.
And "power" equals "force" times "velocity".
We can now swap in the power components 
for this equation we made earlier.
And, voila, we have our equation 
for the battery capacity needed for the truck.
Okay,
jokes aside, this an equation taken 
from an absolutely fantastic paper
by Shashank Sripad
and another lad who needs less syllables in his name,
which goes into depth in this problem.
But I'll give you a quick rundown of its components.
To adequately calculate the force acting on the vehicle,
we first need to calculate the force 
required to overcome inertia,
that is, how much force 
it will take to get the vehicle moving,
which is this part of the equation.
This takes into account the efficiency 
of the electric engines and brakes
and the energy recovered from regenerative braking.
Now, we need to calculate 
the forces acting to slow the vehicle down
such as drag, the rolling friction on the wheels,
and gravity as the vehicle travels uphill.
Musk specified that the range for the vehicle 
was calculated on a flat road,
so this component goes to "zero".
So if you work on mountainous roads, 
this truck may not be for you.
From the event last month, we know that the truck 
has an astounding coefficient of drag of 0.36-
that's slippier than a Bugatti Chiron-
thanks to the lack of air intakes to cool the engine.
We will take the mean rolling resistance 
of the truck tires at 0.0063,
and the average speed at 50mph
(this accounts for city driving too),
and with the average acceleration 
and deceleration at 0.112 m/s²,
and a frontal area of 7.2 m².
The rest are constants that you don't particularly 
need to worry about for this example,
but you can check 
the full calculations in the description
where I've included 
an interactive website that we created
so you can easily change these variables yourself 
to see how they affect the vehicle.
With this tool we can see that the 300-mile variant 
would need a 550-600 kWh batteries,
and the 500-mile variant would require 900-1000 kWh.
With current batteries' energy densities and prices, 
these would weigh 4.7 and 7.9 tonnes,
and cost $108,000 and $180,000 respectively.
These are the two most important metrics
for any company considering buying this truck,
as it determines the exact return-on-investment time.
The batteries for the 500-mile version are going to be more expensive than a traditional truck alone
while having a shorter range 
and smaller hauling capacity.
That's going to make 
the return-on-investment time longer,
even if the operating cost per mile is 
20% lower than a conventional diesel semi-truck.
But profitability is not everything in this world.
This truck will use approximately 
25% the energy of a conventional truck,
thanks to the extremely efficient engines,
and much of this will be provided by renewable energy.
This truck has the potential to drastically reduce 
the greenhouse gas emissions of the trucking industry.
Tesla leading the way on this technology 
and ignoring skeptics like me, while risking bankruptcy
for the sake of improving the planet is exactly 
why I admire Elon Musk so much in the first place.
Honestly, I came into this video 
expecting the truck to be a deeply flawed technology,
After the event, I ranted on Twitter 
about how suspicious it was
that Musk didn't unveil the empty weight of the vehicle.
I honestly thought the whole event 
was created to stir up hype
and generate funds for 
a cash-poor company through pre-orders.
I expected my calculations 
to confirm my preconceived ideas,
but I've never been so glad to be wrong.
There are many other factors that will affect this truck,
but you can investigate them on our site at  battery.real.realengineering
We can see how adding a 5% grade hill for 5% of the journey will increase the battery capacity required
for the 500-mile range by more than 200 kWh
and the weight of the truck by almost 2 tonnes
and increase the price by $44,000.
Go ahead and play around with the tool yourself, 
and if you found it useful
please consider supporting the channel on Patreon.
because this video, along with the website,
was made possible by funding 
from my Patreon community.
Funding from Patreon will always 
go straight back into this channel,
whether it's hiring more web developers
to create cool companion sites like this,
or hiring animators and researchers to help the production quality and quantity of this channel.
Ultimately, with your help, I want to make this the best science documentary channel on the internet.
