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Modeling Utility cost tariff with scheduled power outages

asked 2015-04-15 01:00:38 -0500

Xandrika gravatar image

updated 2015-07-10 20:55:30 -0500

I am running my model in the context of a developing country with scheduled power outages. That means between 2 to 8 hours a day (depending on the month) there is no utility electricity available. In it's turn the building has a diesel backup system to fulfill the energy demand.

As I am only modeling a part of the building I do not want to include the diesel backup system. However, I would like to consider the increased electricity price during power outage in my llife cycle cost analysis. I have created the Time of the Day tariff for the utility costs. But I am not sure how to include in this tariff the increased unit price when diesel gensets are running.

Do you have any advice how to go about it? My question has more a conceptional character. If I do not model the diesel generatore backup system I cannot really put a different unitprice. I was thinking of using the shoulderEnergy to represent the hours when diesel backup system is running. But not sure if this will be working or there is a more clever appraoch.

Thansk a lot.

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What's your question?

  • E+ technical question; How to build a Time of day tariff in EnergyPlus (hint: I/O reference, Example H - Real Time Pricing here)?

  • Or conceptually, how do you choose which hours will have higher pricing than others?

Julien Marrec gravatar image Julien Marrec  ( 2015-04-15 03:22:54 -0500 )edit

@Julien Marrec my question is more conceptionally. Because if I do not include a diesel generator set im my model, I can also not automatically get different unit price.

Xandrika gravatar image Xandrika  ( 2015-04-15 04:16:26 -0500 )edit

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answered 2015-04-15 06:59:53 -0500

Whether you have a diesel generator or not in your model, it doesn't matter from a conceptual standpoint.

Ultimately you'll have to decide when it runs or not, which is what you'll have to do in order to say when electricity is more or less expensive in your case.

Work from what you know: if you know when the power outages usually occur, etc. In the summer it's likely during the day, when there's more cooling needs and transmission lines are stressed and overheated.

Go as granular as what you know can provide. A monthly or seasonal typical time of day tariff might be more than enough.

For example, you could assume that during the winter there's an average 2-hour long power outage that can be anywhere between 10 am and 4 pm. Assume a linear, or if you think it's centered on a given value assume a curved distribution and assign that to your tariff for January.

In the summer you might postulate there's an average of 4 hours of power outage, between 12pm and 4 pm. Assume for example it's centered on 2 pm (when peak cooling is likely to happen) with a curved distribution and assign that to your summer months, etc.

One very important thing: the utility company in the area where you project is located might actually keep track of power outage events. It'd be much better to use historical events to build the above tariffs than to guesstimate.

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@Julien Marrec Thanks for your detailed reply. Fortunately, I have historical data from the utility company. There are forecasts that power outages will be eliminated within 5 years. However, I am doing the cost analysis for 20 years. Is there any chance to limit a tariff in e+ to only the first 5 years of the analysis?

Xandrika gravatar image Xandrika  ( 2015-04-15 07:17:23 -0500 )edit

It's good that you have historical data, it's just a matter of processing it using basic statistics.

Regarding your question, I don't think so. How about you just run the analysis for the first year, escalated that for 5 years, and then run again the simulation with a standard tariff, and escalate that for the remaining 15 years.

I usually deal with any escalation outside of E+ anyway...

Julien Marrec gravatar image Julien Marrec  ( 2015-04-15 08:04:42 -0500 )edit

mmhh, running outside is not an option for me as I am doing parametric runs and optimistaion with jEPlus+EA. That means my Present Value of LCC is an output variable during optimization process. However, I was thinking just to distribute the total hours of power outage in the first 5 years over the whole analsis period. I think, this is a good estimation. Anyway, I will have at least 3 scenarios because there is no secure data available how fast or slow this power outage problem will be solved.

Xandrika gravatar image Xandrika  ( 2015-04-15 12:31:32 -0500 )edit

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Asked: 2015-04-15 01:00:38 -0500

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Last updated: Apr 15 '15