After I finished my last blog concerning how much area it would take to switch to 100% renewable power in California I decided to perform a few "first cut" calculations to see it is really as obvious as I think it is. I looked up power use by the State, various production amounts by energy source and calculated how much power could be produced per square foot of panel per year (based upon 2009 actual amounts for the State). It works out kind of like this:
Total electrical used by California = 205,695 GWh/yr
Production:
large hydro = 25,094 GWh/yr
small hydro = 4,181 GWh/yr
geothermal = 12,907 GWh/yr
renewable = 28,567 GWh/yr
biomass = 5,685 GWh/yr
The amount that needs to be produced in excess of these amounts is 129,261 GWh/yr
There are 6,540,000 single family residences in California. If you assume that each has about 1500 sq ft of roof and can accommodate about 1000 sq ft of solar panels, then the rooftop power would equal about 125,000 GWhr/yr. Thus, there are enough residential roof tops in California to produce about 97% of the additional power needs.
I haven't yet made a guess at the available area on the roofs of businesses, parking lots and south facing windows in tall office buildings, but I think it is substantial. I would think that it is probably at least 25% of the area of the residential roofs. Together, the solar on residential rooftops and the solar on businesses and parking lots would easily exceed the "non-renewable" electrical requirements for the State. Of course, this figure will undoubtedly go up as the cost of solar electricity goes down (because of private investment of locally produced electricity), but there is some extra power available in the figures that I am using. And this does not include the impact of further efficiencies in our use patterns, which could be substantial if we actually make it a top priority.
An interesting feature of this calculation is that there is already about a third of our electrical power produced by renewable and controllable sources which could easily be available for times when solar is not available. This doesn't include the 31,509 GWh/yr we are currently getting from nuclear power plants. This can also be used for power during off solar times. It seems pretty clear that we already have the ability to keep running when the sun isn't shining. Maybe there will be some small shifts required in scheduling the use of power, but it appears that no new systems will need to be designed or built to allow this to happen. Until the system shakes down into a stable supply and demand mode, there is another 116,716 GWh/yr capability from natural gas power plants, which can be used as "peaking" sources (just as they are used today).
Based upon this admittedly simplified analysis, it seems pretty clear that we have a mixture of renewable power plants currently available to allow us to produce all of our electrical needs using renewable sources (including solar) without needing to impact ANY additional land for large scale solar or wind power plants. There are of course some questions regarding the design and implementation of the power grid that will need to be evaluated and modified, but that will need to be done no matter how or where the wind and solar power is to be produced. We are not going to be able to get off of polluting, non-renewable, carbon dioxide producing power without some significant changes to the grid because the grid was never really designed, it grew up topsy to meet the needs as they developed. It will just have to keep doing that and shift in ways that make the new energy sources work.
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