Darwin Scheduler - Min. Energy Cost

Question

Hello, 
 I have questions regarding to Darwin Scheduler for minimize energy cost. 
 At first, when calculating energy cost in Darwin Scheduler, carbon price is infeasible basing on my study WaterGEMS. Please confirm it . However, I have an idea to minimize GHG emissions. That is to set carbon price as Energy price, and select "min. energy cost" as objective. Then I would get the results the total carbon price of tariff electricity. DO you think it is right? My purpose is to minimize GHG emissions. 
 Secondly, will be possible to multi-objective (min. operation cost and min. energy useage) optimizate at the same time in Darwin Scheduler? As I know, it is not possible. If possible, please indicate how to do. 
 Thirdly, the volume of the tank how to balance it? Any consideration for the tank, and how? If not , it means designer have to consider the calculation of the tank at first before setting the models in WaterGEMS. 
 Cheers 
 Michelle

Jesse Dringoli · Accepted Answer

Re: "At first, when calculating energy cost in Darwin Scheduler, carbon price is infeasible basing on my study WaterGEMS. Please confirm it . However, I have an idea to minimize GHG emissions. That is to set carbon price as Energy price, and select "min. energy cost" as objective. Then I would get the results the total carbon price of tariff electricity. DO you think it is right? My purpose is to minimize GHG emissions." 
 If energy cost is correlated to carbon "cost", you could still use Darwin Scheduler with the actual energy cost in place. This would attempt to optimize the energy cost, which (if I understand your situation correctly) would also be the carbon "cost". So, once you've settled on a pump schedule using Darwin Scheduler, you can run the scenario energy Cost tool to calculate the carbon emissions. If this doesn't help, please elaborate a bit on what you're trying to accomplish.

Jesse Dringoli · Answer

Re: "Secondly, will be possible to multi-objective (min. operation cost and min. energy useage) optimizate at the same time in Darwin Scheduler? As I know, it is not possible. If possible, please indicate how to do." 
 The "Minimize Energy Cost" Objective Type will consider both the energy cost of the pump as well as the additional operational cost due to energy tariffs and peak demand charges. If this doesn't help, please elaborate on what objectives you're interested in.

Jesse Dringoli · Answer

Re: "Thirdly, the volume of the tank how to balance it? Any consideration for the tank, and how? If not , it means designer have to consider the calculation of the tank at first before setting the models in WaterGEMS." 
 Could you explain a bit more on what you mean by balancing the tank volume? The energy cost associated with any difference between the volume in the tank at the start and end of the simulation will be considered in the total energy cost, if you include the tank as an Objective Element. (Filling a tank is essentially storing energy for later use while draining that tank uses stored energy.) 
 Also, you can enter maximum and minimum allowable levels for your tanks, in the Constaints tab of your Optimized Study. This will tell Darwin to attempt to optimized the pump schedule such that the tank levels do not go beyond this range. 
 In case you haven't seen it already, there is quite a bit of good information and advice on Darwin Scheduler in the Help, under the topic called "Darwin Scheduler FAQ".

Jesse Dringoli · Answer

Re: "It means that the Multi-Objective for The volume of tank VS. pump capacity such as above drawing, the more volume of tank, the longer detention time, and lower capacity of pumping station. It is case for multi-objective optimisation for the water supply system. I know that it is available using WaterGEMs to set min. and max. level of tank in term of separated calculation of the volume tank. Will WaterGEMS calculate the volume of tank meanwhile optimize the pump station/ pumps?" 
 
 I'm not quite sure I understand what you mean here. I'm also unable to see the screenshot you had attached. Could you try saving as a different file format (such as JPEG) and re-attached, or use the "attachment/options" tab within the Advanced Reply Editor? 
 Generally speaking WaterGEMS will certainly consider all the hydraulic implications of the size of the tank (change in hydraulic grade and volume based on inflow/outflow, pump operating point depending on tank level, etc). The energy cost associated with running the pumps to fill and drain the tanks accordingly can then be calculated in the other tools such as Energy Cost and Darwin Scheduler. As mentioned before, any difference between the starting and ending tank volume (level) is accounted for as a storage "cost".

Wayne Hartell · Answer

Hi Michelle, 
 The concept of Pareto-optimal doesn't come into the Darwin Scheduler optimization since we are not trading off any objective against another. Each optimization is a single objective optimization. You can choose to optimize either cost or energy use. Typically one is a surrogate for the other, but as you have pointed out due to changes in energy tariffs it is technically possible for this to not be the case. You need to decide whether to optimize for cost or for energy. 
 There is currently no option in Darwin Scheduler that allows these two objectives to be traded off against each other. I can't personally imagine such a case where tariffs vary significantly enough that you could come up with enough variation across a Pareto-optimal front to make such an analysis worthwhile, but I definitely would be interested to hear if you believe that that is not the case. 
 Kind Regards, 
 Wayne.

Jesse Dringoli · Answer

Re: "More questions are how to show the energy usage of the solutions when minimize energy cost? And show the energy cost of the solutions when minimize energy usage? If could show, and how to set?" 
 When clicking on one of the saved Solutions, click the Objective Elements tab. Within the Pumps, VSPs and Tanks tabs within there, you will see columns showing the energy cost and energy usage. This will allow you to see the energy usage for a run set to "Minimize energy cost". 
 For viewing the cost of a run set to "minimize energy usage", you could export the solution to a scenario, then run the Energy Cost tool on that scenario.

Jesse Dringoli · Answer

For viewing the cost of a run set to "minimize energy usage", export the solution to a scenario, then run the Energy Cost tool on that scenario ("Scenario Energy Cost" or "Energy Management" under the Analysis menu)

Regards,

Jesse Dringoli
Technical Support Manager, OpenFlows
Bentley Communities Site Administrator
Bentley Systems, Inc.