Calculation error - Crops: Known calculation errors of irrigation model
During the development of the new perennials pathway several calculation errors have been detected for the irrigation model.
- For irrigation emissions both based on volume only and on volume, depth and distance, the reported % of area irrigated is not correctly calculating the respective energy used, but the Cool Farm Tool applies the % of area irrigated twice. This means there is an understatement of emissions in CFT 2.0, potentially significantly where % area is <100.
- For emissions based on volume only, the area affects results when water added is indicated in volume (e.g. L). This is incorrect, as area shouldn't affect results for this calculation method for volume only.
- Results for emissions based on volume, depth and distance are incorrect in CFT 2.0 due to a bug introduced during release - in CFT 1.0 the results were correct. The bug is likely in the unit conversion of fuel/energy emissions factors to kWh. Note: electricity is already in kWh and don't need the MJ conversion. Also, the kWh:L for diesel was probably broken in the update of energy density factors as part of the version release. This means CFT 2.0 is over reporting emissions due to the conversion - for electricity this is at least 3.6x too high.
We want our users to be aware of this. The errors will be fixed as part of the migration of the crop pathway to Cool Farm Platform.