In my recent interview with Will Toor he stated that Wind Energy is cheaper than gas. So using Wind 1/3 of the time (max for wind) and gas 2/3 of the time, that’s cheaper than gas all the time. Forget CO2 emissions, we’re just talking the cost of electricity.
Let’s Do The Math
We need to include the capital costs. With the Wind Farm you need a backup SCGT. For the gas only case we need a CCGT1. I am going to include capital costs, but not ongoing maintenance, people, etc.2.
A 1GW wind farm will cost roughly $1.4b. The backup SCGT3 will cost roughly $713m. So Wind+SCGT is $2.113b. A 1GW CCGT will cost roughly $950m. So Wind requires an extra $1.163b to purchase & install.
That $1.163b needs to be apportioned on an hourly basis. Both Wind4 and Gas Turbines lasts 20 years. That’s $1.163b / (20 [years] x 8760 [hours/year]). That makes the hourly electrical production capital cost of a wind turbine to be $6,663/hr. This is not the total capital cost, this is the additional capital cost.
In other words, Wind, Solar, Nuclear, and Hydro have their giant costs up front and then produce electricity for pennies. But what you are paying for that power does include the capital costs. And for Wind that apportioned capital cost is $6,663/GWh more than the apportioned capital cost of a CCGT. Not counting interest on the money spent to build the system.
Now for purchasing gas. We turn to our good friend the Siemens SGT-9000HL:
SCGT
Efficiency - 43.2%
Power Output - 440MW
Gas input - 81 US tons/hour
7.29 million BTUs/hour/MW5
CCGT
Gas input - 81 US tons/hour
Efficiency - 64%
Power Output - 655MW
4.9 million BTUs/hour/MW6
Gas prices7
Not counting the spike the recent prices have been $3.00 - $4.00/million BTUs
The question then is what does it cost to run the SCGT (2/3s of the time) vs the CCGT (full time) and that’s the gas we need to purchase. Running a SCGT to generate 1GW for 2/3 of an hour the gas costs $14,580 - $19,440. Running a CCGT to generate 1GW for an hour costs $14,700 - $19,600.
Now lets plug it in. The Wind + SCGT for an hour is $6,6638 + [$14,580 or $19,440] = $21,243 - $26,103 while just the CCGT is $14,700 - $19,600. So the Wind+gas is 40% more. 9
Just for grins, let’s assume you can use a CCGT for backup. And it instantly starts up at full efficiency (it doesn’t). Well then Wind + CCGT is $6,663 + [$9,800 or $13,067] = $16,463 - $19,730. Now at the higher gas price they’re equivalent while at the lower gas price just the CCGT is cheaper. Unfortunately CCGTs don’t work that way. The whole reason they manufacture SCGTs is because their quick spin up/down to full power is worth the lower efficiency .
There’s also the interest on the larger investment to build the Wind Turbines. This is presently on the order of 2.72%. That adds about 13% to the total paid but this gets into the value of money over time and so I’m not adding it because I think doing this correctly it’s not exactly the additional 13% paid.
The bottom line is, that Wind + gas is ~ 40% more expensive than just gas. And with a CCGT being ~ 50% more efficient than a SCGT and the SCGT running 66% of the time, their cost to purchase gas is going to be very close. So I don’t see any set of circumstances where Wind + gas comes close to the cost of fueling just gas.
Ireland tried using CCGTs instead of SCGTs for backup power. It did not go well.
This favors wind as it has maintenance & employees for wind and gas.
People will say “but, but, but… batteries or solar or import power or…” The bottom line is first off at present the backup is SCGT or worse (coal and CCGT turned on/off). And second off, those other alternatives have even larger problems.
There are credible examples that a Wind Turbine’s life is less, possibly only 7 years. But we’ll give it 20 here.
81 tons * 39.6 conversion factor / 440MW
81 tons * 39.6 conversion factor / 655MW
Apportioned capital cost so not divided by 3.
The reason the gas costs for both are so close is that a CCGT is ~ 60% efficient while a SCGT is ~ 40% efficient. So they’re burning roughly the same amount of gas.