Last time, I wrote about our energy storage generation: why it's important, what it consisted of historically, and what it looks like today. This post is going to focus on coal. Again, I'm using the data from form EIA-860, with the finalized 2012 numbers released this month.
First up, what coal energy sources are there?
Out of these 42 "Energy Sources", 4 are coal ranks, ordered here in decreasing rank:
- Bituminous Coal
- Sub-bituminous Coal
and two are coal that has been processed in some way:
- Coal-Derived Synthetic Gas
- Refined Coal
Anthracite, Bituminous, Sub-bituminous, and Lignite refer to the coal's rank. Coal rank is essentially the degree to which something has been turned into coal. As the heat and pressure processes work on the original organic components of coal, moisture and other impurities are forced out. This process increases the heating content of the coal, and generally increases its value. High rank coal has greater energy/carbon content, and lower moisture/volatiles content. Here's a handy chart:
Anthracite is the highest rank of coal. It has a very high energy content, low moisture, and relatively few volatiles. Anthracite commands a higher price than lower rank coals, and was generally used in applications requiring consistent high-quality heat, such as steel making. Anthracite's combination of usefulness and rarity means that it is often rapidly exploited as a country industrializes. In the United States, only 0.846% of our demonstrated reserve base for coal is anthracite, and nearly all of that is found east of the Mississippi.
Bituminous and Sub-bituminous are the main ranks of coal used for power generation for two major reasons. The first is that they are the most common, comprising roughly ~89% of our demonstrated reserve base together, split 53% bituminous and 36% sub-bituminous. Second, they're considerably cleaner than lignite. In the grand scheme of things, lignite is practically dried-yesterday peat, direct from your local swamp. Distribution of bituminous and sub-bituminous coal has a distinct geographic split in the United States, which I threw a gif together to illustrate.
It might surprise some of you to see how much coal Illinois has. Despite the state's (my home state actually) massive reserves, there is very little demand for Illinois coal. It's worth taking a brief aside to explain this; I see a few major reasons for the absence of Illinois coal flooding the market (hint: it's basically just not [economically] worth it):
- The coal is generally deep and somewhat tricky to extract,particularly compared to Wyoming's surface bonanza.
- The land it sits under is highly valued for agriculture.
- Coal is already available nearby in less environmentally-stringent states (Indiana and Kentucky).
- The coal industry isn't doing so hot right now, so there's no reason to develop the area.
This, of course, could change. In fact, it might have had shale gas proved a bust and coal-to-liquid and coal-to-gas technologies, paired with cheap and effective carbon capture entered the market strongly. Instead, pilot plants are gasping for air, surviving on a lifeline of rate hikes and federal subsidies.
There is one other important physical characteristic about American coal to keep in mind, western sub-bit coal has a bit lower energy content than bituminous eastern coal, but eastern coal is higher in sulfur. This imbalance in attributes leads to an interesting dance as eastern utilities attempt to maximize their dollar by constantly comparing the cleaner, but more expensive to transport western coal, with the dirtier, but closer to home and higher carbon eastern coal.
So, with those basic coal-in-america facts out of the way, what does our roster of coal generation look like in the United States?
Based on last week's release of the finalized EIA-860 for 2012, there are 1,290 generators whose first energy source is a form of coal. Here's a basic breakdown table of some pertinent facts.
While there have been some refined coal pilots plants in recent years, they didn't show up on the EIA's reporting. Per the discussion of coal rank earlier, it makes sense that there are no anthracite plants, and syngas has a single operating plant, because the ones that are supposed to be online had plenty of technical difficulties, then got knocked on their ass as the price of natural gas plummeted (I'll definitely be getting to natural gas soon, that shift was nuts). For capacity, I'm using the same methods I outlined in my last post.
From here on out, this post will be a bit graph heavy, hope you enjoy!
Again, I'm only working with currently operating coal plants, but what might surprise you is just how old some of these suckers are. While I brought up the median age of construction above, this plot makes it clear just how heavily we invested in coal in the mid-century, and what a dramatic decline has occurred since then. Possibly the most intriguing piece of this figure is the uptick in construction over the last 10 years. I would posit that these plants were planned well before the natural gas boom, and were actually constructed under decreasingly favorable economic conditions. I left the syngas plant off of this figure, because it's only a single point.
This graph fills in a few of the details left out of the prior plot. While the number of annual generator installations decreased dramatically from the 1950's, this figure shows that the new installations were far larger, and implies that the backbone of our current baseload generation began operation 20-30 years later. Another takeaway comes from the twin peaks: bituminous and sub-bituminous. On the installations plot, it appears that bituminous coal handily beats sub-bit in generators, but what it fails to show is the average capacities of each generator, which I calculated after seeing this myself.
These numbers really surprised me when I first saw them (don't forget, that final column is in GW, so 1000x the first two). Honestly, I find the lignite numbers a bit appalling. While it doesn't make up a ton of the final portion (only 5.35%) I would endeavor to get that number even lower. I expressed some not-so-veiled disdain for lignite above while talking about coal rank for good reason. As a reminder, lignite is a brownish coal, with high moisture and ash content. Lignite also requires more processing than higher rank coals in order to be transported safely, so it is generally used close to where it's found. I've tabled the lignite generators, but perhaps you can guess where they are already (hint: check out the map above).
Unsurprisingly, it's the states that have lignite that are using it. It makes sense to use your in-house energy sources for generation politically as you can position yourself as a job creator. In fact, due to the difficulties in cleaning and using lignite in compliance with clean air standards you're going to be hiring more people per BTU of generation throughout your in-state lignite facilities, and spending more to clean each pound of coal that's also (on average) inferior in terms of heat content. So, lignite might be politically expedient, but it's probably economically inefficient. That inefficiency gets worse if you're thinking about environmental impacts, both at the local level (NAAQS), and globally (CO2). However, all of these negative side effects explain the relatively large size of lignite generators. It makes the most sense to consolidate your inefficiencies to a small number of installations where they can be more easily controlled.
I think I'm going to end it here for now. I hope this sheds some light on coal generation in the United States, and made you think a little bit. Next time out I hope to talk about one of the non-regulatory reasons why coal is down, and maybe out (out being a relative term, it's not going to disappear or take a far smaller role in our day-to-day mix anytime soon, just taper off as plants retire): Natural Gas.
I'll leave you with another map, and one to keep in mind moving forward.
* Weighted average was calculated by multiplying each # of generators by the median year for that fuel input, then dividing by the total number of generators. This was done to reduce the influence of the 1 coal-to-syngas plant construction. If an average of the median years is taken directly, the average year is 1978.