BioFuels

Biomass Farming

The bio-masses used for the bio-fuels pathways are:

• Soybean Farming
• Palm FFB Farming
• Rapeseed Farming
• Jatropha Farming
• Camelina Farming

All those farming processes are implemented in GREET. They are using regular US averages fertilizer production and Diesel for non road engine to power the farming tractors and other stationary engines used (pumps, conveyors...)

The products are assumed to be transported dried so there is no need to specify the moisture content of those materials in the transportation processes after those farming processes.

Fuel Production

General Biofuel Production Process Level ModelFile:Biofuels.dia

Bio-fuels production generates a lot of valuable co-products such as SBM, Fuel Gas or Glycerine. In the Excel spreadsheet options are offered on the main page to switch between system level allocation or process level allocation/displacement.

For the process level allocation/displacement method we create two distinct processes Oil Extraction and Transesterification. Each of them have their set of inputs and a definition of the co-products. It is therefore allowed to perform an displacement on the first process and a market allocation on the transeterification process, the co-products treatment method chosen for each process is independent.

For system level allocations, the extraction and transesterification processes are modeled as a single process with two co-products. They are aggregated in a single process to make abstraction of the vegetable oil link between the extraction and trans. processes, thus making them a single system.

Renewable Diesel II Production

Here are the assumptions used for this pathway :

• Yield for oil extraction : 4.7lb of dry soybeans for 1 lb of oil
• Coproducts for oil extraction : 3.7lb of SBM for 1 lb of oil
• Yield for transesterification : 1.17lb of Vegetable Oil for 1lb or Renewable Gasoline II
• Coproducts for transesterification : 0.059lb of Propane fuel gas per 1 lb of Renewable Gasoline II

The structure of the pathway is exactly the same as shown above, the pathway can be found under : LDV Fuels -> Diesel -> Renewable Diesel II -> From Soy Oil

The results of this pathway have been evaluated against the GREET1_2011 Excel spreadsheet for all available types of allocation both for Extraction and Transesterification, however the displacement options have not been validated yet. The results obtained with GREET.net are showing an error between 0.1% and 1.06% compared to the excel spreadsheet. We are still investigating those errors.

Total Energy Calculations

The total energy is calculated in GREET1_2011 as this : ${\color {green}{\Bigg (}}{\color {magenta}{\bigg [}}{\color {red}{\Big (}}{\color {blue}{\big [}}OH(FaTr)+HV(SyBn){\color {blue}{\big ]}\cdot y_{1}}+OH(OlEx)-HV(SyOl){\color {red}{\Big )}\cdot af_{1}}+OH(OlTr)+HV(SyOl){\color {magenta}{\bigg ]}\cdot y_{2}}+OH(Trest)-HV(D2)-E(CoProd2){\color {green}{\Bigg )}\cdot af_{2}}$

For the Oil Extraction process, the overhead is calculated using :

$(E_{in}-E(mainOut))\cdot af_{1}$

The energy content of the co-products are not accounted there. However for the Transesterification process, the overhead is calculated like this :

$(E_{in}-E(mainOut)-E(CoProd2))\cdot af_{1}$

In this one, the energy content of the co-products is accounted, here the co-product is propane fuel

In order to do that in .net we are defining a matrix which details the link between the inputs and the outputs of the process. That way we can trace what is the Basic Resource ( or the share of basic resources) which leads to this product, and when we allocate the energy content of CoProd2 is removed from the basic resources in the total energy vector. In that case Soybean.

Total Emissions Calculations

For the emissions there is no specific calculations as we are only talking here about some kind of overhead, we do not have emissions in and out to balance as for the materials in and out. Therefore the emissions calculations using allocations are straight forward

Biodiesel from Soybeans (Process Level Allocation)

Description of the biodiesel from soybeans pathways using process level allocation/displacement in GREET.