electrical operational cost for the industrial plant 2

[HamidEle]

We are trying to figure out the electrical operational cost for the plant we are designing. The demand load is about 80MW.
The following formula we are using is:

Yearly cost=kWh x hours/year x kWh rate.

The cost for maintenance needs to be provided by the owner.

Did I miss anything?

Any comments would be appreciated.

 

[ScottyUK]

Most utilities have a reactive power charge or penalty. Some will impose charges based on the installed capacity as well as the actual power usage. Some offer preferential rates in exchange for an increased risk of disconnection during system contingency events. Most utilities have different rates depending on the voltage that you connect at. 80MW could realistically be connected to either the primary distribution system or the sub-transmission system

Have you asked your utility for assistance? They are in the best position to help you.

 

[HamidEle]

The client is asking us to estimate the electrical operation cost for the plant. There is one co-gen which is 40MW.
Never talked to the utility about this.

 

[davidbeach]

Never talked to the utility about this.

Your homework isn't even half started yet. In response to your original question of "Did I miss anything?", you've probably missed far too many things to even begin to come up with an answer. If the load is unvarying throughout the year, then maybe, but if there is any variation and the utility has demand charges, you'll be wildly out of whack if you don't have a load profile to feed into a utility billing model. Then there's power factor to consider. Do they ratchet demand and/or power factor or are you only penalized for the billing month? Go have a long talk with the utility.

 

[HamidEle]

Davidbeach,
You are right. I have to do a lot of homework from my side before I can figure out the answer on my own. It is not a straight forward as I thought.

 

[oldfieldguy]

Demand charges. You're assuming steady state load. If your load varies, your utility provider is likely to want to bill extra for the peak. After all, he has to size the system to provide you with the maximum power you need. That's all part of researching the power situation. YOu need to talk to the utility provider.


old field guy

 

[HamidEle]

Say Co-Gen is to produce 40MW for the plant, we would have to buy 40MW from the grid. Does that mean, the operation cost should be based on 40MW, which will be purchased from the utility?

 

[davidbeach]

Will the plant shut down if the CoGen isn't available? If not, then some of the time you're going to need all 80MW from the utility, including all the demand/capacity charges associated there with.

This site is a great resource for many things, but I think this isn't one of them. Part of the problem is that utility rate structures vary wildly. Somebody could give you answers that work very well for their utility but will be grossly inaccurate for your case.

 

[jghrist]

You need to get the rate structure from the utility. It will be different if there is co-generation.

 

[waross]

Hello Hamid.
I won't mention power factor other than to assume that you will provide adequate power factor correction equipment.
Your demand charges may be significant. Under some tariffs the demand charges may be equal to or more than the energy charges.

If I was in your position I would do the following:
1> After determining the plant nominal demand based on connected kW ratings and HP at 746 W/HP I would meet with the utility. I would inquire on several issues;
a> The tariff or tariffs that may apply, and other charges such as but not limited to wire service charges.
b> The utility's requirements for protection.
c> The costs associated connection to the grid.
d> What metering and data transmission equipment is required and what is the cost, (one time and monthly).
e> Possible penalties that may be incurred through failure of plant operators to comply in a timely manner with instructions from the load dispatch center.
There are a lot of other details but this will do for a start.

2> Crunch some numbers to determine a cost per day of running. Then do some scenarios to determine the cost of loss of the generator in extra demand charges for the next 24 months and and any penalties for failure to meet obligations.
You want to familiarize yourself with possible penalties and demand charges so as to be able to come up with fairly accurate ballpark prices under pressure in a clients meeting.

3> Initiate a series of meetings with the clients financial people and senior operating staff. At these meetings you will be discussing modes of operation of the plant and the cost of possible responses to loss of generation capability.
Will the plant continue operating and 'bite the bullet' for the extra charges in the event of loss of generation?
Will the plant immediately curtail loading to limit the extra charges?
Will the generator be dedicated to supplying less critical equipment so that in the event of loss of generation there will be no immediate impact on the grid tie?
Will you operate the generator independently of the plant as two separate businesses?

I expect that you will come away from the meeting to crunch some numbers on some suggestions from the customer for operating patterns.
Likewise the customer will be evaluating possible operating patterns.
It will probably take more than one meeting until all parties are familiar enough with the cost implications to make informed decisions.

Here is a short excerpt from a three page tariff in effect in Alberta, Canada.
Note that in the event of loss of your generator, and an increase in your plant demand of 40 MW the you may be paying 80% of the demand for the next 24 months.
The full tariff is here:

http://www.atcoelectric.com/Rates/t.../2012-04-01 AE 2012 Final Price Schedules.pdf

Price Schedule D32
Generator Interconnection and Standby Power
2012 Final Tariff Application
Approved in AUC Decision 2012-071 (Dated: March 22, 2012)
Sheet 1 of 3

Availability

For Points of Service served by the Company with on-site generating equipment connected to the
distribution system, which may be used to supply load at the same site.

Supersedes: 2012 01 01
To provide standby power to the on-site load in
the event of a forced outage or derate of on-site
generating equipment, to provide power for generator
startup, and to provide supplemental power if
the on-site demand requirements exceed the generator capacity.

To provide credits to Generators for reduced DTS charges from AESO.

To charge Generators if the Point of
Delivery attracts STS charges from AESO.

For interconnection of the generator to the distribution system.

The Point of Service must be equipped with 4-quadrant interval data metering, for both supply and
demand, the cost of which will be in addition to the charges under this rate.

The billing demand for the Transmission charges shall be the higher of:
(a)
The highest metered demand during the billing period (excluding any demand delivered and billed
under Price Schedule D33);
(b) 85% of the highest metered demand (excluding any demand delivered and billed under Price
Schedule D33) in the 12-month period including and ending with the billing period;
(c) the estimated demand;
(d) the Transmission Contract Demand (TCD);
(e) if any of the above are equal to or greater than 1000 kW, 80% of the highest metered demand
(excluding any demand delivered and billed under Price Schedules D33) in the 24-month period
The full tariff is here:

http://www.atcoelectric.com/Rates/t.../2012-04-01 AE 2012 Final Price Schedules.pdf

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[HamidEle]

Thank you all for the excellent inputs. It is a complex topic and needs lots of experience on Utility connection. We will initiate meetings with the client operation rep. and get things started.

 

[lightman196]

Hi HamidEle

You can build your tariffs in something such as:

http://www.powerwinsoftware.com

or

http://www.energylens.com

and even play with load profiles. It takes some getting use to but its powerful. Good luck.