Edito Barcelona 11/10/2008

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Dear Charlie,

I wanted to make a new fuel (biodiesel) in "Fuels" which is a blend of diesel and methyl ester. I have some assumptions of the characteristics of methyl ester such as gross calorific value and density.

To make the blended fuel (biodiesel), however, I have to enter its (biodiesel's) gross calorific value as well as its density and other characteristics. Would it be possible for LEAP to just calculate the gross calorific values and other characteristics as the weighted average of the two fuels being blended?

Or is there any other way in LEAP to represent blended fuels?


Thanks,
Edito

Charlie Heaps 11/10/2008
 

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Hi Edito,

If you want to enter biodiesel as a new fuel in LEAP then you will have to calclate the weighted average characteristics (density, energy content, etc.) offline (e.g. in a spreadsheet) and then enter that into LEAP's General: Fuels screen.

Another option is to keep the two fuels separate and specify devices (e.g. vehicles) with two or more fuels (e.g. diesel/methyl esther). Each would have different characteristics and you would also specify a different set of emissions factors for each. The advantage of this method is that you can then dynamically switch between fuels (i.e. alter the blend fraction) from one year to another, independently of any stock turnover calculation for the vehicles. This can be quite useful for simulating a policy that specifies a gradually increasing penetration of biofuels.

I hope this helps!

Charlie

> Dear Charlie,
>
> I wanted to make a new fuel (biodiesel) in "Fuels" which is a blend of diesel and methyl ester. I have some assumptions of the characteristics of methyl ester such as gross calorific value and density.
>
> To make the blended fuel (biodiesel), however, I have to enter its (biodiesel's) gross calorific value as well as its density and other characteristics. Would it be possible for LEAP to just calculate the gross calorific values and other characteristics as the weighted average of the two fuels being blended?
>
> Or is there any other way in LEAP to represent blended fuels?
>
>
> Thanks,
> Edito

Claudio Alatorre Frenk 11/10/2008
 

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Dear Charlie

It would be good if we could find an alternative way to model this.

Let's assume that we are building a scenario with x availability of biodiesel. It seems to me that your approach means that we would first need to "artificially" create downstream the demand for this biodiesel.

When you mix small percentages of biodiesel with diesel, or of ethanol with gasoline, you don't need any special engine. This means that you don't need to create the demand downstream.

In other words, the biodiesel used in the country is simply equal to the available amount: It is defined by the supply side, not by the demand side.

Therefore I think that the best approach, and the one that ressembles more the reality, would be to create a new fuel called for example "Diesel-B" (or "Gasoline-B" if we were mixing gasoline with ethanol).

Diesel-B means "any mixture of diesel and bio-diesel that can be used in standard diesel engines".

Since biodiesel and diesel can have different energy densities, this new fuel should be measured in Joules, and not in liters.

Then you create a transformation unit that mixes diesel and biodiesel, This unit is called "mixing station".

The vehicles do not demand diesel: They demand the new fuel called "diesel-B".

The rule of the mixing station would be as follows: The mixing station should firstly use any locally available biodiesel, and then fill up with diesel in order to meet the demand of "diesel-B"

(A different rule would be defined if you have a mandated percentage, as in Brazil: then the mixing station needs to get x amount of biodiesel --if it is not locally available it needs to be imported-- and then y amount of diesel.)

"Diesel-B" is somehow similar to electricity. Consumers demand electricity and do not care how it is generated.

Is this feasible?

Best regards

Claudio

Edito Barcelona 11/11/2008
 

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Dear Charlie,

Thanks. For the meantime I will do the second option.

Blending becomes an issue when there is a projected penetration of several biofuel blends (like the 5%, 10% and 15% of Indonesia). It would be easier and would minimize error if LEAP calculates the characteristics of a blended fuel with the user only giving the composition (fraction of each fuel) of the blend.

Anyway, your reply was a big help.


Best regards,
Edito