A front-page article in last week's Business Journal got me thinking again about solar energy and wind energy in Arizona. The article was about BP's potential development of a 425 megawatt wind farm near Kingman. The plant, only in the preliminary stages of consideration, would produce twice the output of the Solana Generating Station (currently under construction near Gila Bend).
Before I launch into my wind-versus-solar debate, though, I want to make clear one caveat: if a company like BP wants to invest the capital to build a wind farm in Arizona - which will create jobs and generate tax revenue - then more power to it. The wind-or-solar issue only becomes a real debate when:
1) State or local governments are providing incentives to the developer (then we have to think about the best use of taxpayer dollars);
2) A wind developer and a solar developer are competing for access to the same land; or
3) The question is about which technology the state will get behind (there is something to be said for pushing for Arizona to become the "go-to" solar place - for generation as well as R&D and manufacturing of the technology).
So, assuming that the discussion falls into the context of one of those three questions - I think we should have a statewide discussion about the extent to which we're really working to develop AZ as the solar capital, and whether or not it makes economic sense to do so - let's consider: in Arizona, comparing solar to wind power generation, which makes more sense?
Point 1: In terms of resource potential, Arizona ranks much more highly than other states on solar and relatively low on wind.
The resource potential of wind in Arizona is fair at best - that's where the 63-megawatt Dry Lake Wind Project is, near Holbrook. The area near Kingman where BP is proposing its mega-farm is rated only marginal in a wind power resource potential.
Source: National Renewable Energy Laboratory
There are many other states that rank far more highly than Arizona on wind power potential.

Source: National Renewable Energy Laboratory
In contrast, among all U.S. states, Arizona is tops on both photovoltaic and concentrating solar power resource potential.
Source: National Renewable Energy Laboratory
Source: National Renewable Energy Laboratory
Point 2: But on capital and operating cost and capacity factor measures, wind power rates better than solar power.
On capital costs, solar (both photovoltaic and concentrating thermal) are significantly more than onshore wind.
Source: National Renewable Energy Laboratory
On operatng costs, though, onshore wind ranks in between solar photovoltaic and concentrating (thermal) solar.

Source: National Renewable Energy Laboratory
Capacity factor is a measure of the ratio between actual energy output and potential output if the plant were running at full capacity. Both solar and wind power rank relatively low on this measure, as wind power is only generated when it's windy and solar when it's sunny. Among the three, though, wind has a slightly higher capacity factor than concentrating solar (thermal) and solar photovoltaic.
Source: National Renewable Energy Laboratory
I'm sure BP, Abengoa Solar, Ibedrola Renewables, NextEra Energy Resources, and the other companies involved in wind and solar in Arizona understand the costs and benefits of building their particular type of power generation facility in the location they've chosen. But when the government is going to pony up tax dollars to help defray those capital costs, I want to be sure that we understand the costs and benefits, too - and that we're making the most efficient decisions among all the energy-resource choices.


