#3: Scaling Onshore Wind Farms
Replacing coal-fire plants with wind
I wanted to talk about something that most of us have probably seen at one point driving along a freeway. Wind Turbines
Wind turbines work by converting energy through a series of phases. Wind energy is converted to mechanical energy as it spins the blades. Mechanical energy is then used to spin a rotor which passes magnets over coils of wires, which produces electrical energy.
The thing with wind is that it doesn’t blow all the time, and different areas in the country are windier than others. In the US, wind is only blowing about 30% of the year on average. This is called the capacity factor.
The Thunder Spirit Wind Farm in North Dakota has a capacity factor of 45% while the Shepherds Flat Wind Farm in Oregon only has a capacity factor of 22%.
How far can wind get us?
To answer this question, I’d like to take a look at the Roscoe Wind Project, a 780 MW wind farm in Texas. It has a capacity factor of 30% which is about the national average. It produces 2,174 GWh per year which translates to 2,174,000,000 kWh. Let’s just call it 2 billion kWh per year.
Ignoring the intermittency of wind, this is an average of 6,000,000 kWh per day.
There are 627 wind turbines operational there, so that’s about 10000 kWh per day for each turbine installed.
It occupies 100,000 acres in total, so that’s about
Just for fun, let’s see what it would take to supply all Texas electricity requirements with just wind. The average Texan consumed about 40 kWh of electricity per day.
The population of Texas, where Roscoe Wind is located is about 30 million. This means we would need about 2,00 wind farms the size of Roscoe.
Is 200 a lot?
Short answer: Yes. The upfront cost of constructing the Roscoe Wind farm was over $1 billion dollars, which is typical for a wind farm of that size. So to build 200, it would cost $200 billion dollars. If Texas pays for this over 30 years, with no interest on the initial loan, it would still be about 6.6 billion per year. The state of Texas collects $60 billion dollars in taxes per year.
Even worse, wind energy production is also very space inefficient. Roscoe is about 100,000 acres in size. Wind farm densities typically average 1MW / 4 squared km. So, 100,000 acres also is inline with what we’d expect for a 780 MW farm.
200 of them would be 20 million acres. That comes out to be about 12% of the total size of Texas. It’s worth keeping in mind however, that this space isn’t wasted. Wind farms are typically built on actual farms, so the same land can produce crops and electricity.
A reasonable plan for wind
Obviously, no one is suggesting replacing all electricity with just wind. One thing we can do immediately is to start chipping away at CO2 emitting electricity production.
In this case our candidates are:
Coal: 90% of coal is just being used to generate electricity. We can basically replace coal mines with wind farms.
Natural Gas: 36% of natural gas is being used to generate electricity. Same idea here.
Before we can go too far there, let me break down the “Renewable Energy” part of this graph into its components: Wind, Solar, Hydro, Biomass & Other so we can see where we are today.
Going back to our energy system diagram from last time, the easiest thing to do is replace energy sources that are already producing electricity. Let’s try to reduce some of the coal-fired power stations with wind farms.
Lots and lots of wind turbines
Let’s see what a more realistic wind plan for the US could look like.
The United States supplies 2.7% of total energy usage through wind. Let’s say we 4x the nation’s wind capacity.
Note: You might ask why we didn’t just choose a 5x or 10x or 100x. Surely if we just pick a bigger number, things will be better. We’ll find out a bit later the consequences of having a source as variable as wind.
This would grow our wind energy percentage from 2.7% to about 11%. 90% of the coal we currently use is for generating electricity. We can replace a significant chunk of this with renewable wind
Dammit, who turned the lights out again
Wind is unpredictable. It fluctuates with short term weather patterns and annual seasonal changes. Here is a graph showing just how different wind energy production is over the course of a month at the Tehachapi Wind Farm in California.
We’ll discuss the details of the electrical grid and energy markets later, but for now you just need to know one thing: the amount of electricity produced at any given time has to equal the electricity being used, otherwise, we get blackouts.
Unfortunately what this means for us is that if the wind stops blowing, then we’ll have no power. In addition to your TV going out, critical infrastructure like traffic lights, and hospital equipment also lose power. We’ve seen what happens, most recently in Texas, when a blackout occurs, especially if it’s unexpected.
I’ll discuss the problem of how to deal with intermittent energy sources later, but I’ll give you some things to think about for now:
When our energy system becomes more and more reliant on intermittent sources of energy, we need to have backup sources of energy when production drops. For example, we can:
Build a really big battery which gets charged when we have a large supply of wind energy, and releases energy when supply drops.
Have a backup source of energy that can supply power when the main source drops. For instance, a coal-fire plant that produces small amounts of energy when wind production is robust, and scales up as supply drops.
But this answers the question for why we can’t just 10x, or 100x our wind energy right off the bat: It’s just not that reliable.
By increasing wind production 4x, we were able to reduce our dependence on coal. Making our energy system look like this:
There is a big caveat: The unreliability of wind causes a lot of problems.
Let’s hop over to the right side of our graph and see what we can do there to decrease our dependence on fossil fuels by electrifying transportation.
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