Nobrainer’s Think Tank

Yesterday I was researching a new solar power plant that is going to be connected to the grid. I started with very little information, so I had to wade through a lot of false-leads to get the information I was seeking. In the process though, I ran across info for one solar power plant, the economics of which I found to be amazing.

A school in Pennsylvania chose to build a 1MW solar PV plant on something like ~6 acres, that I guess they didn’t have anything else to do with. The total cost was $4.8 million. This is not the amazing part. To get it built, they got grants to cover 51% of the costs. Most of that was federal and state grants. But they also got about 10% from the local utility. Still, that huge subsidy is not the amazing part. What surprised me, was that they get renewable energy credits for each megawatt-hour they generate, to the tune of something like $300. That’s the equivalent of 30 cents-per-killowatt-hour. And the local utility has to buy these credits. So for every killowatt-hour they produce, they don’t have to buy power from the grid at a cost of 11 cents/kwh and they then get paid 30 cents/kwh.

If this school had to rely only the power the solar PV farm produced to pay back the investment, it would take about 30 years. But with the freebies, the payback period is 4. 4 years! After that, I reckon they’ll be revenue positive as long as the price of the renewable energy credits doesn’t tank. Good deal if you can get it.

… for linking to PrisonPlanet and easily the dumbest article I’ve read all year. “Obama’s Blocking Of New Power Plants Triggers Nationwide Blackouts” says Prison Planet. Look, I hate Obama as President, but that claim is bullshit. Pure bullshit. I have to figure that they are “stuck on stupid.” And they must be to a) figure that Obama has had so much influence in just over 2 years given the lengthy, multi-year process involved in building a new power plant and b) claim “the inability of power companies to meet demand is almost exclusively a consequence of the Obama administration’s publicly stated goal to bankrupt the coal industry” to ignore other factors such as major natural gas supply disruptions caused by “[f]rozen natural gas wellheads in the Rocky Mountains and pipeline problems in Texas.”

I’ve written quite a bit about the technical merits of wind energy. The downside to wind energy seems to be the political and economic merits. To wit, this intro paragraph from Bloomberg says it all:

Wind-energy companies agreed to buy more parts from U.S. suppliers, and a labor union promised to join in lobbying Congress for a requirement to use more renewable energy.

[EDIT: I received an email from Kent Hawkins informing me that I correctly identified a mistake and that he has since corrected the problem in his calculator. Thanks, Kent. Sorry for the sarcasm here.]

I began Part 6 by saying that “one of my new favorite blogs” is “MasterResource”. I’ve since edited that post because I ended up publishing it several weeks after I wrote it and, in that time, realized that the blog isn’t that great.

Case in point: Poster Kent Hawkins has created a CO2 savings calculator. He seems very proud of it. He’s even made updates to it!

The model relies on this graph. It uses a percent reduction in efficiency due to required turndown and applies a corresponding CO2 penalty.

The model seems reasonable; reductions in efficiency lead to CO2 rate (the amount of CO2 released per unit of electricity) penalties.

Seems.

But the model is wrong. As are the outputs, which frankly don’t pass the sanity check.

First, let’s consider the sanity check. Based of the initial post, there’s a chart showing fuel reduction for a given scenario (the scenario is has major flaws, but that’s not the point of this post).

Then we see that for the scenario, despite fuel savings, we can actually have CO2 emission increases.

Let’s sanity check that. The model assumes all the fuel is natural gas. The model reports that less natural gas is being used. And the model reports that more CO2 is being emitted. In other words, the CO2 per unit of natural gas is increasing. The model says that natural gas is a variable carbon content fuel. That is insane. Thus, the sanity check fails.

Going back to the initial graph, we see that for a given efficiency and fuel type (i.e. any spot on a curve) there’s a corresponding CO2 rate. For proper analysis, Kent should not be assigning a pre-defined penalty based on some efficiency change. Rather he need only pick the CO2 rate of the curve that corresponds the efficiency in question and thence proceed.

I’ve re-created the given graph for natural gas fired plants.

You can create a similar graph for heat rate (the amount of fuel burned to product a unit of electricity). This is another way of viewing efficiency.

The heat rate and CO2 rate graphs are very similar you’ll notice.

So similar, that if you plot heat rate VS CO2 rate, you get a straight line!

Let me change the values on the y-axis.

It’s still a straight line, and the coefficient is 117.08 lb/MWh… exactly what the EIA says it is. And why is that? Because that’s how you properly convert. I multiplied the heat rate by the CO2 coefficient. The CO2 coefficient for a fuel is not going to change based on plant efficiency. The change in CO2 has to be directly proportional to the change in quantity fuel used.

Here’s the data for my charts:

Kent Hawkins should have used the above graph in the model. If he had, then he wouldn’t have created variable carbon content fuel. He should also have sanity checked his work. Hopefully he and the others at MasterResource will approve my comment, notice it, correct their model and their faulty conclusions.

On the morning of March 12th, one of my new favorite blogs, MasterResource (edit: In the time between March 12th and when I published this post, I had already deleted MasterResource from my RSS reader after I quickly realized it isn’t that great), hit on the wind issue. Although I don’t know that the post is completely correct and fair, it did avoid the errors I have prevalently seen elsewhere. However, he does link to a story that gets things wrong. Energy Tribune titled the article, “Wind Power Exposed: The Renewable Energy Source is Expensive, Unreliable and Won’t Save Natural Gas.” This article by Peter Glover and Michael J. Economides in Energy Tribune is another example of writers misrepresenting their source.

Energy Tribune seems to base a large part of their story from a paper “in the journal Energy Policy [by] gas turbine expert Jim Oswald.” The actual paper costs $20, but there’s a freebie copy at WindWatch.org]. ET’s bold statement:

In August, the most in-depth independent assessment yet of Britain’s expanding wind turbine industry was published. In the journal Energy Policy gas turbine expert Jim Oswald and his co-authors, came up with a series of damning conclusions: not only is wind power far more expensive and unreliable than previously thought, it cannot avoid using high levels of natural gas, which not only it will increase costs but in turn will mean far less of a reduction in carbon dioxide emissions than has been claimed.

First, the paper was sponsored by the The Renewable Energy Foundation, which makes me question whether or not it was an “independent assessment”.

Second, the paper, which is interesting, really isn’t that great a paper. It’s not a bad paper; it seems well written. However it doesn’t really say a lot (try reading a lot of papers and this will be shown to be a common phenomenon). The paper basically presents an interesting wind model and then briefly postulates how traditional power plants and utilities seem likely respond to such a situation.

Here’s what the paper actually says, quoting from the abstract (but rest assured, I read the entire paper):

There are two main results. First, the model suggests that power swings of 70% within 12 h are to be expected in winter, and will require individual generators to go on or off line frequently, thereby reducing the utilisation and reliability of large centralised plants. These reductions will lead to increases in the cost of electricity and reductions in potential carbon savings. Secondly, it is shown that electricity demand in Britain can reach its annual peak with a simultaneous demise of wind power in Britain and neighbouring countries to very low levels. This significantly undermines the case for connecting the UK transmission grid to neighbouring grids. Recommendations are made for improving ‘cost of wind’ calculations.

That’s pretty much it. A relatively boring paper has become “damning” because some writers have low reading comprehension and/or truth-telling skills. Sounds like par for the course to me.

Elsewhere on the intertubes an engineer named Henk Tennekes chimes in with his opinion about wind as an energy source. That opinion is pretty well summarized by his first sentence, “[w]ind energy is an engineer’s nightmare.” His basic point is that designing and maintaining windmills is a challenge; a difficult one at that, and that therefore they’re a bad idea.

It’s completely laughable and appreciably sad that an engineer would dismiss an entire technology because there is difficulty involved. Certainly nuclear power plants, for which he advocates, represent only the simplest and easiest of engineering tasks. Nuke vs Windmill? Oh yeah, the windmills are the difficult ones. I’m also certain that all those engineers who currently design and build wind mills agree that they’re living a nightmare.

There is a bit more worth quoting.

Since the power generated by modern wind turbines is so unpredictable, conventional power plants have to serve as back-ups. Therefore, these run at far less than half power most of the time. That is terribly uneconomical – only at full power they have good thermal efficiency and minimal CO2 emissions per kWh delivered.

This is another contradiction to Courtney who argued that conventional thermal plants can’t really operate at all below their peak, especially not at “far less than half power.” Tennekes here also tries to pull an engineering sleight of hand. Rather than mention total emissions, he talks about emissions rates only at the thermal plant.

Why don’t politicians listen to engineers?

Well, Henk, I can think of a few reasons…