As we say
Riaz, “No need to highlight our math lessons, a simple rule of 2 is enough! ", Do not hesitate.
So, “solar electric car + batteries” (VSEB) or not?
Approach A :
Our VSEB saves 237 MJ per cent, or 17,4 kg of CO2, of fossil energy (note A).
Assessment over 20000 km: our VSEB allows us to save 237 MJx200 = 47400 MJ or 17,4x200 = 3480 kg of CO2
Approach B:
Objective, to remove conventional thermal power plants (those that pollute the most). That is to say, we keep our fossil vehicle but we feed the electrical network with our solar panels. Over the year, our 34m2 (for 20000 km) of solar panels produce 810 MJ / year (note B) x 34 m2 = 27540 MJ / year. Before becoming final energy (at the outlet), we must integrate the distribution efficiency (90%) which gives us 27540x0,9 = about 24800 MJ of final energy.
Taking into account the average efficiency of conventional thermal power plants + distribution (36%, see page 12
http://cocyane.chez-alice.fr/pdf/electricite_et_co2.pdf ), so we saved 24800 MJ / 0,36 = 68900 MJ of fossil energy. At the rate of 0,083 kg of CO2 per fossil MJ (note C), we saved 5700 kg of CO2.
Let's summarize:
Approach A (VSEB) allows us to save 3480 kg of CO2
Approach B (based on the fossil car) allows us to save 5700 kg of CO2
So, let's keep our good old fossil car and push the manufacturers to finally make us these cars "
2 liters per hundred super light super profiled "But fossils ...
Clearly, unless I am mistaken, the VSEB electric car is seriously questioned unless there is a radical change in context. It remains to be verified that a “non-solar” recharge of electric cars at night (when demand is low) is not at least of partial interest.
The error is human, to your calculators… (I check later and update if necessary)
Michel Kieffer
PS:
Elec certainly right in the long run, but we all understand that today there is much more effective and much more urgent to do ...
PS: This reasoning is valid whatever the individual mode of production of electricity: wind turbine (cf. suggestion of
Lietseu), micro hydraulic power plant
PS: In addition, let's quickly return to approach A: our car loads at night which puts lead in the wing of approach A: there is a basic problem due to lack of sun at night!
PS: that does not mean that the individual must invest in solar panels: one euro invests in insulation today is much more effective than one euro in solar panels.
Notas:
A - Reference vehicle: car with diesel engine, vehicle mass around 1300 kg:
• Data: assumption of average diesel engine consumption: 6,5 liters per cent; yield 35%; diesel density 0,85; diesel energy 43 MJ / kg; releases: 0,073 kg of CO2 per MJ of diesel fuel (3,16 kg / kg)
• Onboard energy to complete 100 km (U2) = 6,5 liters x0,85x43MJ = 237 MJ
B - Energy produced per m2 of solar panels: 225 kWh / year (estimate, this value seems rather high) = 810 MJ / year
C - We are removing very polluting thermal power plants and not hydraulic power plants! For this reason we should not take our 0,128 kg of CO2 per MJ of final energy but 0,083 kg of CO2 per MJ of fossil secondary energy (this is an average, see page 26
http://cocyane.chez-alice.fr/pdf/electricite_et_co2.pdf )