Texas Grid Capacity Issues

Texas has its own electrical grid with very limited connections to the rest of the country.   This is how Texas can legally do things its own way,  instead of being forced to follow federal rules mandates.  By and large,  this has served fairly well,  but we do have a history of capacity shortfalls during chronic extreme summer cooling loads,  and now a couple of severe winter cold snap events. 

We in Texas are also faced with two imminent problems over which we have no control:  (1) fast population growth is very rapidly driving up demand,  and (2) the already-begun national electrification of the surface motor fleet will also massively drive up demand,  more than anyone wants to admit.  We will very soon need factor 1.5 (or more) increase in our electrical generation capacity,  and in the capacity of our transmission lines to carry that much more electricity.

There is a third problem,  over which we do have some control:  pollution emitted by our energy sources.  Some of this is “traditional” pollution,  such as particulates,  smoke,  and chemicals from the smokestacks,  plus that coming from the fuel extraction and transport activities.  Those include mining wastes,  spills from pipelines and rail cars,  etc.  Some of it is greenhouse gas emissions,  which,  it is now quite clear,  must also be reduced.

I found some data regarding the mix of energy sources on the Texas grid,  from the office of the State Comptroller of Public Accounts.  The data is for calendar year 2021,  which is recent enough to support making reasonable estimates.  I put those data into a spreadsheet and used it to create the multi-color pie chart,  plotted to scale,  in Figure 1.  I simply drew the two-color pie charts,  not-to-scale.

Figure 1 – The Current Mix of Energy Sources, and What We Have To Do Long-Term

Our basic situation is that we need to change the mix of energy sources to reduce emissions,  and we need to greatly increase overall capacity,  but we do not have to do those things in that order,  or even together!  Plus,  we still have some time to get it all done,  as long as we get started now.  

There are currently some practical limitations to the contribution of renewables (wind and solar).  Their intermittency requires emergency surge capacity in the other sources,  which limits those renewables to around 25% of the mix at most,  until there is such a thing as an affordable grid-scale energy storage technology,  ready to deploy.  Currently,  there is not!  But it may soon become available,  in the next very few years.

Of the energy sources,  two are fossil fuels:  coal and natural gas (very few power plants today use oil,  and none that I know of,  in Texas).  These have problems with emissions,  and those numbers are not the same for the two fuels.  A typical large power plant has an energy conversion efficiency in the neighborhood of 40%,  meaning only 40% of the fuel’s combustion energy can be turned into electricity.  This varies somewhat,  and is a little bit lower for surge plants,  and a little bit higher for base-load plants.   But that figure is close enough to use,  for estimating things,  as I did in Figure 2.

Figure 2 – Basic Data for Coal and Natural Gas

The hand calculations in the figure show that natural gas has a wetter exhaust than coal,  which affects air pollutant chemistry,  but it also has only about half the greenhouse gas emissions of carbon dioxide!  Its smokestack plumes are typically very much cleaner,  of the other airborne pollutants,  and it does not create nearly as much extraction wastes and troubles as coal does. 

On the other hand,  its main constituent,  methane,  is also a very potent greenhouse gas,  and currently a lot of it is lost to the atmosphere by leaks and flares.  Its mass production in the US now requires fracking,  which generates a lot of contaminated frack water,  the disposal of which can demonstrably cause earthquakes,  if not done responsibly,  which drives up costs somewhat. 

Thus,  there are a lot of risks to weigh,  some of which most people do not readily think about.  But as indicated in Figure 3,  the better choice is natural gas on a risk basis.  Plus,  here in recent years,  it is actually cheaper than coal,  on a price per unit releasable combustion energy basis.  It simply takes more tons of coal than natural gas,  to release the same energy,  as shown in Figure 2 above.

Figure 3 – Weighing the Risks of Coal Versus Natural Gas

What that suggests is the two-part plan presented below in Figure 4.  Initially,  we need to increase capacity rapidly,  but we need to do it without making the pollution and greenhouse gas problems worse.  I ran estimates for reaching 150% of current capacity,  by not increasing the coal in the mix,  but instead adding large amounts of natural gas,  wind,  solar,  and nuclear.  In my estimate,  all these but coal were increased to factor 1.615 times current contributions. 

I did not decrease coal,  I simply left it at its current energy contribution.  To achieve the 150% capacity,  the other sources had to increase more,  including natural gas,  which actually raised the fossil fuel contribution from 57 to 65% of the mix.  However,  by shifting more of the fossil contribution from coal to natural gas,  the emissions of carbon dioxide only increased to factor 1.33 times current levels.  That’s actually a decrease in emissions,  in a relative sense!

As coal plants age and decommission,  the plan in Figure 4 says to replace them with natural gas and nuclear plants in the near term.  We already know how to build both.  We will need to devise a way to incentivize this capacity increase,  so that installed capacity stays ahead of the increasing demand,  instead of falling behind and responding too late to increasing demand,  as it does now.

Note also the very small change in the renewables contribution to the mix:  to 25.8% of the new,  higher total,  compared to 24.0% of current.  That’s close enough to the fuzzy 25% limit on the intermittent renewables contribution,  that we could start this capacity increase without waiting for an affordable grid-scale energy storage technology!  Except for coal,  it’s just “more of everything”.

By the time we get this near-term change done,  that storage technology will very likely be available,  and we can start on the longer-term portion of the Figure 4 plan:  replace the fossil fuel plants as they age and decommission,  with renewables and nuclear!  Electricity from renewables is demonstrably cheaper than electricity from nuclear,  but we will need to keep both of those sources in the mix.  You do not want to place all your eggs in one basket! 

And note:  this does not prevent keeping some natural gas plants in the long-term mix,  as those are the very best choice for meeting demand surges.

One other note:  hydroelectric power is generated in Texas,  but the numbers are too small compared to the other sources,  to even show up in the plots.  We cannot really increase it,  because we have already dammed all the dammable rivers in Texas.  I should not have factored it up by 1.615,  but 1.615 times 0 is still 0,  so it did not matter.

Figure 4 – There is a Near-Term and a Long-Term Component to the Plan

We have people appointed by our elected politicians comprising the leadership of ERCOT.  That is the organization that,  together with the utility companies themselves,  manage the Texas grid. 

Up to this point,  neither ERCOT nor our elected politicians have chosen to incentivize increasing capacity.  That is a matter of public record.  It is precisely why capacity increase lags demand increase.  And,  that is the real source of the chronic summer and winter cold snap power shortfall troubles we have seen in recent years.   Which,  also as a matter of public record,  do cost lives!

And that lack of incentive for increasing capacity is what must change,  or none of this improvement plan (or any other) can happen!  There is no way around that ugly little fact of life!

The key here is the elected Texas politicians:  they make and enforce the laws,  and they appoint ERCOT’s leadership.  Thereby,  that is how they control what happens and what does not.  

The current crop of elected politicians has proven unwilling to address this critical need for incentives to increase excess capacity.  We’ve already seen it,  rather egregiously in the death toll and dislocations seen in the extreme cold snap of February 2021.  All that means is we Texans have the wrong people in those elected offices.  Their poor decisions have been killing Texans!

I suggest that if the current bunch will not serve the public good,  then we need a new crop!  This is an election year.  Vote the current bunch out.  It doesn’t matter who the opposition is,  you cannot do worse than what you have,  but you might do better with somebody different!

Or maybe you like no electricity for your air conditioner in August,  and no heating in extreme cold snaps! 

You decide!

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Here as Figure 5 is an image of the spreadsheet where I processed the data and made the plots,  for those who want to see how I did this:

Figure 5 --  Image of the Spreadsheet Used to Process the Numbers and Make the Plots

These two multi-color pie chart plots were used in two of the figures above,  the rest were all drawn in the old Windows “Paintbrush” utility (not the later 3-D version).

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