The Power of the Sun

I recently happened to hear a discussion the radio amongst a group of people arguing against hydraulic fracturing (fracking).  For those of you less familiar with this technology, it is essentially a method that uses high pressure water and chemicals to cause cracks in what is very hard rock (see a good graphic by a site otherwise opposed to fracking).  This hard rock, shale, also contains natural gas.  Without the benefit of the cracks opening up more pathways for the gas, the production (rate) from shale would be too low to justify the expense.  With fracking however, production from shale has virtually all of a sudden become viable.  Most importantly, enormous tracts of shale that have been known to exist for a very long time such as the Marcellus and Barnett shale formations have become major gas producing regions.  This has had two very important (and related) effects:

1. The price of natural gas has plummeted.  This is mostly driven by supply but a weak demand due to reduced industrial activity (something to do with the recession) and a warmer winter last year (something blamed on global warming) has not helped.
2. The US now has a very abundant source of domestic energy.  This has been a rallying cry for many groups and now natural gas offers that solution where the US should be able to sustain itself for a few decades.  At least when it comes to energy.

Back to that discussion on radio - this group was vociferously against fracking and pointing out the many supposed issues with it.  As I pointed out in my previous post, I am fine with the discussion, however I want to hear solutions and options.  If an intelligent group is going to take our time with their views then it should further society's discussion on this topic.  As listed above, fracking has produced some very tangible benefits; benefits that this country has needed.  So if we are going to stop fracking then the alternative should be able to similarly solve the problem.  Fortunately, the host towards the end asked the group what the alternative would be.  What are our options for providing the electricity to power our homes, manufacture our goods, perhaps fuel our cars, and host that very radio show?  There was some ho'ing and humming, after which one guest said, "...well there's solar.  For example a school in NYC has installed solar panels on its roof and now gets part of its electricity from those panels."

So there you have it.  We will produce our electricity needs from solar.  The US generated 416.5 million MWhrs (megawatt-hours) of electricity in Jul 2012 (Energy Information Agency).  With 744 hours in the month of July, that is equivalent to 560 GW of power generation capacity cranking out electricity 24/7.  Note: the US has over a 1000 GW of generation capacity.  If we are to reduce our requirement for natural gas (responsible for ~415 GW of that capacity), then solar power would have to produce at least a measurable percentage of this, preferably with the same reliability and at the same cost.  I agree that technology may or will improve so let us not focus on cost or reliability (as important as they are).  Let us instead look at the amount of solar energy available.  The map below is the "solar resource" or insolation in the US.  The northeast (including NY) is at about 4 kWhr/m2/day while the southwest is the highest with around 7 kWhr/m2/day.  

Source: National Renewable Energy Lab (www.nrel.gov) - US DOE

Let's do the math.  At the highest insolation - 7 kWhr/m2/day, we can generate 210 kWhr of electricity for every square meter of solar panel per month.  So if we wanted to generate the 416.5 billion kWhr of electricity that was consumed in July from solar panels, we would need nearly 2 BILLION square meters, or 200,000 square km of solar panels.   To put this number in perspective, the entire state of Nebraska is 200,000 square km.  Arizona, which has the highest solar insolation is a little bigger at 295,000 square km.  So if we wanted to power the US with solar power, we would have to virtually empty out Arizona and cover it with solar panels.  This number does not even take into account the area that would be required to store the solar power for use at night.  And this is idealized based on the the total amount of solar energy available without any consideration for the inefficiencies of the solar system.

I wish to be clear, solving our energy needs will require a solution that encompasses all options.  Renewables like solar and wind have a place and are great options for where it makes sense (small residential use, water heaters, light non-essential utilities, etc).  Where they do not make sense is grid level power generation on a massive scale.  They do not make sense on cost, land use, or reliability.  I am happy to continue investing a limited amount of my tax dollars funding the development of these technologies, but they cannot be touted as THE solution to our energy needs.  Until something else truly novel is discovered, the solution is offered by a mix of natural gas and nuclear.  Think about this the next time you power up the device you just read this on.