Get Energy Smart! NOW!

Blogging for a sustainable energy future.

Get Energy Smart!  NOW! header image 2

Playing math games with something in a recent @EIAgov report

June 1st, 2016 · No Comments

Joe Romm’s Renewables Are Leaving Natural Gas In The Dust This Year opens

In the first three months of 2016, New electricity generation in US, Jan-March 2016the U.S. grid added 18 megawatts of new natural gas generating capacity. It added a whopping 1,291 megawatts (MW) of new renewables.

The original title: “U.S. Grid Added 70 TimesMore Renewables ThanNatural Gas In First Quarter“. That title — with a simple mathematical division of 1291 by 18 — led to some complaining and even implications that Romm was attempting to mislead due to capacity factors.

As a quick review,  all generation sources have different use and production rates.

The net capacity factor of a power plant is the ratio of its actual output over a period of time, to its potential output if it were possible for it to operate at full nameplate capacity continuously over the same period of time.

Nuclear power plants, for example, in the developed world are about 90% capacity utilization/capacity factor (. Have a 1 gigawatt (1000 megawatt) reactor and, over time, one can expect the plant to average 900 megawatts of constant electricity delivery to the grid.  Dependent on many issues, wind might be considered 25% (roughly world average) to 40%+ (new, reasonably well placed/designed installations).  Solar perhaps in the 15-20% range. And … Thus, to achieve the same total electricity production of a 1GW capacity nuclear power plant, one might require 2.5-4GW of installed wind or 5-6GW of solar capacity.

The comments about capacity factors, attacking that original title, ranged from ‘reasonable’ sort of comments to absurdist whining as a means to attack renewables.

But, for fun, lets play a math game of notional values w/18MW of natural gas and 1291 of renewables.

Here are three assumption sets off the top of the head:

  1. NatGas at 50%, renewables well done with average of 33%
    1. This is  likely that this is high end re the natural gas as the 12MW  are likely peaker, not baseload(natural gas combined cycle plants, baseload generation often, averaged 56% in 2015), generation.
    2. This seems likely in shooting range of the actual renewables with the wind/solar mix (though my supposition is that the 33% is probably in range of 10-20% lower than actual production — this is very amenable to analysis but requires going through all the additional renewable sites w/the projected capacity figure for each of the sites.
  2. NatGas as peaker plus, 20% (rather than <5%); renewables at 25%
    1. This is perhaps in range of the NatGas (likely somewhat high though, see 2012 charting)
    2. Pretty pessimistic re the renewables, with weak wind production.
  3.  NatGas is 100%; renewables are just 20%
    1. This is incredibly high (actually essentially impossible) re the NatGas as it assumes 24/7/365 operations with zero minutes of downtime for maintenance.
    2. The renewables is undoubtably low, with an assumption of systematically poor production from the installed wind farms.  This likely is in the ballpark of just 60% of the likely renewables figure.

So, with those assumptions, what how do each of these scenarios play out in terms of electricity production on average.

Scenario 1 provides the equivalent of 9MW constant NatGas with renewables 430MW constant. Okay, renewables only 48X the natural gas …

For scenario 2, NatGas is 3.6MW constant and renewables at 318MW constant. Renewables at 88X the natural gas constant.

For scenario 3 (which is absurdly unrealistic), NatGas is 18MW constant and renewables are ‘just’ 258MW. In an absolutely unreasonable ‘worst case’ outlier scenario, the added renewable capacity will deliver >14X the electrons to the grid as the new natural.

Okay, moving away from added faceplate capacity to actual contributions to the electrical grid, the ‘reality’ is that the additional renewable electricity capacity will provide somewhere (reasonably) between 25X and >100X the electricity as the new natural gas systems.

Hmmm ….

Really want to whine that the title was 70X focused on faceplace capacity figure?


Be Sociable, Share!

Tags: analysis · electricity