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174 comments on Andris Piebalgs : getting a sense of proportion
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Plants are typically only 1% or 2% efficient at producing energy we can use.
A solar PV panel can produce 15% or more but only if it is kept at 90 degrees to the suns rays, I suspect the calculations have been made assuming this - what is it if the panel is just flat on the ground like the plants?
I doubt I (or most people) could afford to use current PV panels to power any car I might want to use - no oil, no car! - PV is VERY expensive, especially at high lattitudes.
The efficiency of the Photosynthesis process for plants is indeed typically 1% or 2%. But only a very small part of the energy is converted into usable oil. According to the article I referred to, rapeseed converts only 0,15% of the solar energy into oil!
Roughly speaking, a tracking PV panel produces about one third more electricity as an optimally positioned fixed PV panel (not flat on the ground). A panel lying flat on the ground produces about 85% of an optimally positioned fixed PV panel (at least in Germany, on the equator the optimal position is flat on the ground). But than you could use the whole field, instead of only about one third, because then you don't have the problem of one panel shadowing another. In total you would even have more yield pro hectare, but at a much larger cost because you need a lot more panels!
And that brings us to costs. In Germany, they have a feed-in tariff of 35.49 cents/kWh for freestanding PV-plants. So, a car consuming 16kWh/100km has a 'fuel cost' of about 5.68€/100km... The fuel cost of a typical 7.4 l/100km (32mpg) gasoline car is considerably higher! (at least in Europe) And feed-in tariffs are falling (up till now 6,5% a year, from next year on probably 8,5%), whereas oil prices are rising. For a PV powered hybrid car, not as much the price of the "PV fuel" is the problem, it's the battery cost!
R G
You are forgetting the taxation component of automotive fuels. The government will eventually have to tax "automotive" electricity if we all start using it. The price will rise 6 fold then. How they will do this, I don't know but they will find a way!
It would make sense to tax mileage and perhaps adjust that tax according to the 'fuel' efficiency of the car and perhaps price in some form of peak congestion charging.
I suspect this would create a new industry in 'clocking' although many of the big brother propsals for satelite tracking on vehicles would resolve this.
Jevons' Paradox in operation?
Jevons' Paradox in operation?
Comparing biofuels to PV-powered plug-in hybrids is a valid comparison, but several things must also be examined;
1. EROEI of the PV panels: How much energy was used in the manufacture compared to lifecycle energy output?
2. Hybrid extras: How much more energy was used to make the batteries, electric motor, and any additional items?
3. Costs: What are the cost differences between the two alternatives to the consumer?
4. Environment: How do the environmental impacts of each compare?
5. Food prices: What will the food price differential be between the two alternatives?
I currently have both a hybrid and a PV-powered house, so the above comparison is of great interest to me as well.
Incidentally, a field of tracking PV arrays could also be a source of switchgrass or other cellulosic ethanol feedstock, as seen in the main photo at this link provided by RenewableGuy above. It would be nice to see a translation of this article, which compares ethanol and PV-powered plug-in hybrids.
As has been mentioned before here and on Andris blog, simply continuing the same level of automobile use should not be considered a sustainable approach. Increased levels of mass transit, buses, biking, and walking are certainly more sustainable, and rely on best land use planning practices. For those unable or unwilling due to current distant suburb/exurb locations, velomobiles with electric boost can be considered the next step.
Of course, this crashes head-on with the size and influence of the EU auto industry;