Liliana Gonzalez 10/10/2013

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I read a previous post related to the same problem I'm having now. Flex Fuel cars in Brazil run with both gasoline and ethanol but as Gregers pointed out before how can you model it if the the share between gasoline usage and ethanol use is unknown?

I did what Charles suggested and set up the car as a category/folder branch called "Flex Fuel Car". Then I created two technology branches underneath it marked "gasoline" and "ethanol" to account for use of each fuel. I inputted the data for both fuels but still don't know how to determine the share (stock share, sales share). I'll appreciate your comments.

Taylor Binnington 10/10/2013
 

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Hi Liliana,

Excuse the (slightly) long-winded answer. There have been a few questions on this topic recently, so I'd like to refer similar questions to my answer here.

If you're doing a stock turnover model in the transportation sector, I would suggest that in your demand branches you create a 'Transportation Technology' device (the small wheel icon). Underneath this, you'll notice that the technology's fuel appears as a separate branch - you can add additional fuels here.

Notice that the Stock Share and Sales Share variables allow you to input data only at the level of the Transportation Technology. Examples of transportation technologies might be 'Diesel Truck', or 'Flex fuel car', etc. Other variables (Fuel Economy, Device Share, Mileage) can be specified for each fuel individually, that the technology consumes.

The way you interpret these variables will depend on whether you're modeling a flex fuel vehicle (one capable of switching fuels) or some kind of blended fuel (E25, for example). If you want to model a vehicle using blended fuel, the Device Share would be analogous to the volume share of of the fuels in the blend. You'll also want to ensure that the Fuel Economy as well as Mileage variables are *the same* for each fuel, to reflect the fact that they are burned simultaneously to travel the same distance, and with the same efficiency (here, though, the fuel economy should represent that which would be achieved from using the blended fuel). Another valid option would be to create a separate fuel in LEAP's fuels database that you use to represent the pre-blended fuel, and then just use that as a single-fuel input.

On the other hand, for a flex fuel vehicle, each fuel's Device Share variable can be thought of as the fraction of time that the vehicle is using that fuel. Again, you need to ensure that the Mileage variables for each fuel are *the same*, even though it's true that the same vehicle could actually be traveling different distances using each fuel.

In either case, however, you do need to exogenously specify some fuel share - either the blending ratio or an estimate for the time ratio that a flex fuel vehicle uses each of its fuels.

Hope this helps,

Taylor

Liliana Gonzalez 12/8/2013
 

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Hello Taylor,

The explanation was very helpful as usual! Thanks

Just a quick question about the second option in which you define both different mileages per fuel and fuel share.

Let's say a new vehicle runs 15,000km. A Plug-in hybrid would be defined as a vehicle running 40% electricity, 60% gasoline and in addition 6,000km on electricity and 9,000km on gasoline (to get 15,000km/year).
*A BAU scenario assumes that 100% gasoline-ICE run 15,000km/year as well.
*While scenario B assumes Plug-in hybrids and gasoline-ICE.

When comparing scenarios, total mileage shouldn't be the same? It is not redundant to define both different mileage per fuel and fuel share?

I hope I made myself clear enough.

Thanks again,

Liliana

Taylor Binnington 6/18/2014
 

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Hi Liliana,

I think you're right, sorry for the confusion. I've modified my answer above, accordingly.

Taylor

Stephanie Morse 11/26/2019
 

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Can you please explain if there is a good way to incorporate plug-in hybrid vehicles if I am NOT using the stock turnover method, but rather categories and technologies?