Where do we go from here? The future of power generation.

 "But life is very short and anxious for those who forget the past, neglect the present, and fear the future" - Lucius Annaeus Seneca

There has been ongoing discussion at work about the direction the electrical generating business is heading.  The discussion is about where things are going for us power plant guys, career-wise.  By sheer coincidence, the stoic quote for today is very appropriate.  We will discuss past, present and future.

Forward:  I'm not going to discuss greenhouse gas and climate change.  That is beyond the scope of this post.  This post is about changes in the generating industry and their causes.

Over the past 15 years or so, utilities have been ridding themselves of coal-fired generation.  There are several reasons for the retirement of coal-fired power plants:

• Carbon Dioxide emissions.  Of all the ways to generate electricity, coal emits the most carbon dioxide per Megawatt of electrical power.  There is a lot of carbon in coal, and you have to burn quite a lot of coal to make a Megawatt, because coal-fired power plants aren't all that efficient - about 35% of the energy from combustion becomes electricity.  
• Heavy metal pollution.  Among other environmental issues with coal are trace quantities of heavy metals like arsenic and mercury in the coal.  Some of these toxins go out the stack, because no filtration system is 100% perfect, and they also end up land-filled in the ash.  The mercury released from coal-fired power plants bio-accumulates in fish, and is the reason that pregnant women should not eat fish - it is harmful to development of the unborn brain.
• Economics.  The staff at a coal-fired power plant is large, because coal-fired facilities are very maintenance intensive.  A 500 Megawatt coal-fired power plant might have a staff of 50-60 people.  The fuel and ash handling systems need daily upkeep and repair, and the equipment requires a large operating staff - fuel handlers, several outside and control room operators, ash handlers, and more personnel for the sulfur scrubbing section.  A similar-sized natural-gas fired plant will operate with roughly half that staff.
  

Below:  A coal-fired power plant.  These are easy to identify, because the wet sulfur-scrubbing process leaves a lot of steam in the stack gas.  The stacks are narrow and are quite tall.  This height is due to the need to safely diffuse/disperse exhaust gas that contains only 2-3% oxygen.  Coal-fired plants have inclined conveyor belts to load coal into silos, and they frequently have large settling ponds where ash is dumped.  You will also see coal piles, which are commonly delivered to the site by train.

Below:  A molecule of coal - one of thousands of possible molecular arrangements.  It's mostly carbon, with the odd sulfur and nitrogen atom, which also cause pollution issues.

Natural gas-fired power plants:

Natural gas is mostly methane.  Methane is composed of a single carbon atom with four attached hydrogen atoms.  The energy release comes from breaking the four hydrogen bonds, and this combustion event releases just one carbon atom.  From the standpoint of carbon-release and environmental toxins, this fuel is much cleaner than burning coal.  Furthermore if the methane is burned in a combined-cycle power plant, 60% efficiency can be achieved.  So... less carbon emissions per Megawatt due to the carbon content of the fuel, and higher efficiency, so even less carbon emissions than coal.

Below:  The combustion reaction for methane with oxygen molecules from air.

Below, a natural-gas fired combined cycle plant.   These also are easy to identify.  At the right is an enormous inlet air filter, like the one on your car, but several stories high.  The gas turbine exhausts into the boiler - the gray object with the stairs and all the pipes.  The stacks have a large diameter, because in addition to air for combustion, gas turbines require a lot more air for internal cooling.  As a result of the large quantities of air required, the stack is wider across than a coal-fueled plant.  Lastly, the stacks are not usually very tall, because gas turbine exhaust contains about 13% oxygen - while normal air contains about 20% oxygen.  The stacks don't have to be very tall to diffuse/disperse exhaust that contains this much oxygen.

The point of the above discussion was to explain how and why natural gas fuel is quite a bit cleaner than coal, and why natural gas power plants have been replacing coal-fueled power plants in the US.  There is another reason for the displacement of coal: The cost of natural gas has been falling.  

The coalbed and shale fracking boom has produced a great deal of natural gas.  The added production caused by fracking has reduced the cost of natural gas from $5-6 per MMBTU, down to $1-3 per MMBTU, where it is highly competitive on a purely cost-basis against coal.  If you consider the environmental issues with coal, fracking has helped to make natural gas a clear winner.

Until very recently, coal had the economic advantage of being inexpensive to strip-mine out of the dirt in the Wyoming Powder River Basin.  While natural gas is cleaner to burn and thus a preferable fuel, it had always been fairly expensive, even in modern, high-efficiency gas turbine power plants.  This cost situation has recently changed. 

Natural gas is produced by drilling hundreds of deep wells, installing a small pipe from each individual well to a central gathering point, treating the gas for sulfur compounds, and then compressing the gas to force it into a specialized pipeline.  

The heavy-wall gas pipeline then transports the natural gas hundreds of miles to end-users, and several compressor stations might be required along the way to boost pressure.  This is very expensive infrastructure to build out.  Once built, however, the operating costs are fairly low.  Obviously you want to have a huge and reliable source of gas as well as large demand before investing in such a large and expensive project.

Thanks to fracking, vast quantities of inexpensive natural gas have become available - partly as a by-product in the search for crude oil.  As a result of fracking and infrastructure build-out, natural gas has become inexpensive.  This reduced price is part of the reason that for the past 10 years, natural gas power plants have displaced coal-fired plants.

Here's an article from the US Department of Energy, saying the same thing.

However, even with this rapid increase in the use of natural gas, things will *not* stay as they are now.  Below is a chart of electrical generation by energy source.  With this chart it's clear that natural gas (blue) has been squeezing out coal (tan).  Overall electrical use has remained flat since about 2008.  Also note that renewables (green) are taking a larger share of the generation.

This is where the situation gets interesting for a guy who makes a living making electricity:

The electrical utility and generating industries have always had to deal with change - both technological and political change.  Power plants turned away from liquid fuels (distillates) during the 1973 Arab Oil Embargo - liquid fuel became too expensive.  Nuclear power plants arrived on the scene in the 60's through the late 80's, and it was assumed that would be a major thing going forward...

Below:  Three Mile Island.  Unit 1 still works OK.

Nuclear energy was not how things went, of course.  Three Mile Island and Chernobyl pretty much sealed nuclear power's fate from a public relations standpoint.  This past decade, over 100 coal-fired power plants have closed or been converted to fire on natural gas.  Deregulation of monopoly utilities and the addition of independent power producers (IPPs) has destabilized the industry economically.  Things are moving faster than they did in Edison and Westinghouse's day.  Or maybe not - I wasn't there.

The current major change that the energy industry is facing is the move toward carbon-neutral power sources.  It's becoming apparent that these newer high-efficiency combined cycle power plants have been an interim technology between coal and zero-carbon electricity.

If you had told me as recently as five years ago that modern natural gas power plants would get shut out of the energy markets, I would have called you crazy.  But today in many places, electric utilities are being required *by law* to switch over to non-fossil energy sources - and they have a very limited time to become zero-carbon. 

Utilities are scrambling to build wind generation, upgrade their hydro installations, add solar power, add biomass power, and install pumped-storage if the terrain allows it.  Additionally they are offering large incentives to customers who install rooftop solar or reduce their energy demand by installing more efficient furnaces and appliances.  These utility companies *will not* be renewing energy contracts with carbon emitters, nor will they be building new power plants that emit carbon.

 Below:  Several different solar power projects on the Carizzo Plain.

How the switch to renewables is happening and what is driving it forward or holding it back:

The change is piecemeal, and tends to be regional in nature.  State politics plays a large role in the speed at which the process takes place.  Some states are embracing the move to renewable energy, while other states are trying to prevent the switch from happening.  Availability of renewable energy resources will play a huge role as well - some regions have large reserves of untapped wind and solar power, while other regions do not.  Economics will play an important role in how quickly or slowly different regions switch to renewable energy.  One thing is clear though, and that is the direction things are heading:  Combustion for power generation is on the way out.

I'm nearing the end of my career, so I can ride out the change-over to renewable energy without career disruption.  It's the younger fellas that have to worry.  Some of them don't want to believe that this is happening, because it may soon cause them a mid-career shake-up.  I understand the desire to believe that your job will always exist, but we all have to face reality.  The reality is that utilities are going to obey the law, and the law is moving in a definite direction.

We are dealing with a rapidly-changing energy landscape.  In the near future, there might be just a few fossil-fueled generating units.  They would likely be unmanned remote-start simple cycle peaking gas turbine units that could ramp to full load in minutes.  These would be used very sparingly, and only to support max electrical demand, or during intermittent periods when renewable sources fade.  

This scenario is not carbon-neutral, but it is far less carbon than a power plant running 24-7 all year long.  If carbon reduction is the main goal, this would be an interim solution until a utility could reach the 100% renewable goal.  The utility could purchase carbon offsets - perhaps by purchasing old clunkers to get them off the road.  

Below is an advertisement for a GE product to meet the need that I described above.  When they say "meeting the need for rapidly changing energy demands", what they are alluding to is sudden fall-off in renewable energy due to weather (wind) or nightfall (solar).

 

Below:  Coolidge Generating Station, an unmanned remote-start peaking facility - one of the handful of fossil-fired power stations that have been built since the boom of the early 2000's.

Personally, I would have preferred to earn a livelihood *not* adding carbon to the atmosphere for the past 35 years, but the anti-nuke crowd pretty much shut that down as a career option.  I hope they are enjoying the world they fought so hard for.  The old nuke plants (which emit no carbon) will all be gone soon enough.  Strange times.

I feel bad for the younger guys in this business though.  Wind farms and solar panels don't require the wide-ranging knowledge and skill set that operating a steam plant does, so the pay probably isn't as good in those jobs.  I always felt lucky to end up in a career that couldn't be off-shored or handed over to an illegal immigrant.  It looks like these well-paying jobs are also an endangered species.

Is this view of the future correct?  I don't know.  My predictions haven't been all that great lately, but this would seem to be just following several long-term trends instead of a global pandemic.  Time will tell!