Hi All
And there's more.
Those pushing electric vehicles often use energy pollution saving as a
strong positive. But is this actually so?
Yes emissions are reduced at the point of vehicle use. But they are not
reduced overall emissions except in very limited circumstances. With an
electrical supply system that is 100% derived from burning coal it is
possible to work out how much CO2 is emitted at the power stations compared
to a diesel car of the same size. Allowing for power station efficiencies,
transmission line losses, charging and discharging losses, etc, electric
cars generate around 3.8 times more CO2 than diesel cars! So until around
75% of electrical power used comes from renewable sources electric cars are
a negative re environmental impacts.
And then there is the issue of powering them up. Really needs to be a manged
situation where charging times are controlled to be outside the evening
peak. Otherwise there will be a huge need for extra power supply sources.
Regards from
John Lambert
MIEAust, CPEng 180785, Member ASME, ACRS, SAE
Bachelor of Engineering (University of Melbourne, ARMIT (Mechanical)
Director and Company Secretary, John Lambert & Associates Pty Ltd, ACN 090
833 873 ABN 59 090 833 873
235 Wandana drive, Wandana Heights, Victoria Australia 3216
Phone: Intl +61 3 52491228 Local 03 52491228
Fax: Intl +61 3 52491146 Local 03 52491146
Mobile: Intl +61 4 17033258 Local 0417033258
Email: <mailto:[log in to unmask]> [log in to unmask] Website:
<http://www.johnlambert.com.au> www.johnlambert.com.au
From: Technical, operational and economic aspects of road freight
transportation [mailto:[log in to unmask]] On Behalf
Of David Cebon
Sent: Tuesday, 28 November 2017 9:29 AM
To: [log in to unmask]
Subject: Tesla electric truck: too good to be true?
Tesla's claims for its new electric truck
<https://www.tesla.com/en_GB/presskit#semi> require some scrutiny. Tesla
claims that the new truck will have a range of 800kms and an energy
consumption of 1.25kWh/km. Running 800km will therefore require 1000 kWh of
energy: in practice a 1300 kWh battery. Suitable lithium-ion batteries for
electric vehicles cost $150/kWh today and are expected to fall to $100/kWh
by 2021. This suggests a 2021 battery cost of $130,000: approximately equal
to the current average price of new heavy truck in the US (in the Class 8
category).
The specific energy of lithium-ion batteries is 0.1 kWh/kg - 0.25 kWh/kg.
So the weight of a 1300 kWh battery will be between 5.2 and 13 tonnes. A US
Class 8 truck has a maximum gross weight of 36 tonnes, 8 tonnes less than
the equivalent UK lorry. In weight terms, US trucks are relatively
inefficient by international standards. US carriers must therefore use
their maximum payload of 21 tonnes very effectively. The weight of the
battery in an electric truck is likely to constitute 25% to 60% of this
available payload. Even after allowing for the absence of a fuel tank and
lighter electric engine this payload penalty will deter many potential
users. A fleet operator might require 4 electric trucks to carry the same
load as 3 diesel-powered vehicles.
Elon Musk promises that his electric truck "will blow your mind clear out of
your skull and into an alternate dimension". However, in the real world, a
vehicle offering at most 3/4 of the payload for double the capital cost does
not seem a very attractive proposition for the road freight industry.
David Cebon
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