Topic: Modelling distributed energy systemsSubscribe | Previous | Next
Anne Marit Melbye 6/12/2015
1089 Views Hi,
My question regards the modelling of distributed energy systems. I am modelling energy demand in buildings, and want to investigate the residual electricity demand, i.e. compare the final and useful electricity demand.
First, a quick intro to the model: the residential sector is a sum of different building categories, each specified for existing, refurbished and new buildings. The demand is disaggregated in heat demand, electricity demand and cooling, each with different fuel shares. My question regards the electricity demand in showing the results.
Electricity demand has a technology mix of 1) electricity from grid, 2) Solar PV and 3) Micro CHP. The result I am interested in is final & useful electricity demand, i.e. the sum of electricity from grid, PV and micro CHP.
I have now included micro CHP in the heat demand fuel share, with the coproduction of electricity. When I do this, I can not see the final and useful electricity demand in a good way; I can investigate the results in my electricity demand branches, but then micro CHP is not included in the result.
I have been thinking of alternative ways as well: 1) I can specify a new fuel for micro CHP. Still, I will have the same issue. 2) I can include micro CHP in the electricity demand branches, in addition to the heat demand branches. But, if I do it like this the primary demand result will not be correct.
How should I build the model on the electricity side to show the useful and final electricity demand the best way? Is there a way to build the model so the final & useful electricity demand can be extracted easily?
I have attached a simplified example.
Thank you very much.
Best regards,
Anne
Test el demand.leap [5]
Taylor Binnington 6/17/2015
1083 Views Hi Anne,
It would likely be clearer if you represented micro CHP on the transformation side of the model, rather than the demand side. I'm not certain if you intend to build a transformation module that produces "on-grid electricity", but you can also build one which generates "off-grid electricity". One of the processes (or power plants) in this module may be a micro CHP plant. You could even assign a co-product of a fuel called "micro CHP heat" (I see you're already familiar with creating custom fuels in LEAP's fuel database).
Once you set this up on the supply side, you would then create demands for each fuel on the demand side (demands for on- and off-grid electricity, as well as regular heat and micro CHP heat, if you want to make the distinction). However, these demand branches would be technologies with final energy intensity, rather than useful energy intensity - since you've already incorporated the efficiency information of each technology on the supply side.
In your sample model of demand, the two results you're looking for were a) final and b) useful energy demand. Analogous results using the framework which I've described would be a) Transformation: Inputs (for your distribution generation transformation module) and b) Demand: Energy Demand Final Units.
This would be my first suggestion. It's possible to accomplish what you're trying to do in only the demand branches, but it's less transparent (though there are situations when it's the only option).
Hope this helps,
Taylor
Anne Marit Melbye 6/18/2015
1079 Views Hi Taylor
Thank you for your reply.
Can you please elaborate on how it would be possible to model this on the demand side? I have not used my transformation branch (for now at least). If possible, I would like to keep all the data and demand side technologies on the demand side in Leap.
Br
Anne
Taylor Binnington 6/18/2015
1078 Views Hi Anna,
I'm happy to try, but let me make sure I first understand which result you're really looking for (please be as specific as possible). When you state that "micro CHP is not included", are you referring to the demand for micro CHP-produced heat, or the demand for micro CHP-produced electricity? Also, in results view it is possible to view both Demand: Energy Demand Final Units and Demand: Useful Energy Demand, by fuel and by branch, so I'm not sure which result you're looking for that isn't satisfied by one of these options.
Best,
Taylor
Anne Marit Melbye 6/24/2015
1035 Views Hi Taylor,
When micro CHP is included in the fuel share under the heat demand branches, coproduction of electricity is subtracted from the resulting heat demand. Under the electricity demand branches, resulting coproduction of micro CHP is not visible. "Micro CHP is not included" in the results for the electricity demand branches.
In fact, all the results I am interested in can be found. Since my model have so many el and heat demand branches, the results can not be easily seen (without multiplying/subtracting results for all the different branches). I therefore want to investigate whether there is a more straightforward way to do this.
To sum up, the results I am interested in: the sum of the heat demand in all (heat) branches & the sum of the electricity demand in all (el) branches. Both for useful and final energy demand.
Br Anne
Taylor Binnington 6/29/2015
1 Like 1031 Views Hi Anne,
Regarding your first paragraph - the coproduction of electricity by heat\microCHP_th will only appear underneath the Households\heat branch: you will not see this coproduction appear underneath the branch Households\el. It creates a negative electricity demand at the heat\microCHP_th branch, which reduces the aggregate demand for electricity. The clearest way to see this is using the Energy Balance view (inset), which will show you final energy demands.
To your summary question - have a look at results views Demand: Energy Demand Final Units and Demand:Useful Energy Demand, displayed for all fuels, with your mouse cursor selecting the top "Households" branch of the tree. Are these results what you're looking for?
Taylor
