Tuesday, January 3, 2012

The Problems with Solar

Happy 2012, everybody!  I hope you're already planning your End-Of-The-Conversations-About-the-Mayan-Civilization party (I sure am) and making wild and exuberant statements about your actions in the New Year.  I, for one, pledge to think one unprecedented thought every day.  Today's thought: feet could maintain mirror symmetry both across the body and across the foot if the big toe were in the middle.  Shoe production could cost half as much!*

Having painted an optimistic portrait of the Solar Revolution, lets take off the rose-colored sunglasses for a closer examination of the difficulties with solar power.

And the beginning of a new year is a good time to do this!  For the sun has just turned around its decreasing presence of the fall, and is beginning to rise moments earlier and stay up seconds longer.  Last year, on the shortest day our sun was in the sky for only 9 hours, 4 minutes and 33 seconds** in Cambridge, Massachusetts.  Of course, the Sun plans to make up for it in the summer, with the longest day in 2012 planned for 15 hours, 17 minutes and 6 seconds on June 20th.

This annual variability seasonally aggravates the primary difficulty with solar power: NIGHT.

Yes, unlike Kalgash the Earth has but a single star and a high (365:1) rotation to revolution ratio, implying that for about half the time we receive (almost) no light from our primary star.  From a solar power perspective, this is a real pain.  The electrical grid was designed around fossil fuels, and requires 24-hour-a-day electricity generation as a necessary component: whenever someone somewhere plugs in a toaster, an electric company has a power station online burning the midnight oil.  And while on average there's enough luminous energy from the sun to power everyone's ovens and iPhones, all of it is concentrated in just one-half of the day (and less in the winter).  Plus people tend to use the most energy in the mornings and evenings, not during the middle of the day.

The solution to the day/night quandary will necessitate as big a change to the grid as installing the solar panels themselves.  We'll need to store the energy when the sun's up, so we can use it when the sun is down.  The proponents of renewable energy know this, and everything from batteries with liquid-metal or nanotech to flywheels to giant capacitor banks are being researched.  While small-scale electricity storage has undergone a couple revolutions recently (any of you reading this on a phone may be aware), large-scale electricity storage is actually kind of difficult.  I'll come back to that point sometime and discuss it in a bit more detail.

What about the seasons, though?  Remember there's a six-hour swing in the length of the day during a Boston year, and that'll get bigger the further north you go.  And unfortunately, those shorter days are also when energy use goes up, as people break out the space heaters and take long hot showers.  Storing electricity from day into night is eminently doable, but it's unclear how electricity could be effectively stocked up in the summer months for use in the winter.  Maybe some chemical storage process would work best if such storage duration became necessary (like making hydrogen fuel from water using electrolysis).

Alternatively the more regularly-cooked southern states could become major electricity exporters in the wintertime.  There's plenty of space in (say) Texas to manage giant solar farms.

The other big problem of course is weather.  We also enjoy rotisserie chicken on rainy days; to say nothing of snowy ones!  Shoveling the driveway is enough of a pain without having to shovel the solar panels as well.  To this, I suppose there are two solutions.  Solution the first: build giant solar facilities in deserts.  The Mojave desert (as I stated before) could theoretically provide enough solar electricity to power the entire US, and they have the nice dry air that lets the sunlight through.

Solution the second is that solution to so many of life's problems: zeppelins.  Or space lasers.

It's unfair, really.  The sun is trying so hard to keep us warm and happy and able to use power tools, and the Earth just won't cooperate, all spinny and tilted and weatherish.  Well, the spinny part is probably a good thing.  And the weather, come to think about it.  Maybe we could do something about the tilt***.  In the meantime, it's just as important to work on electricity storage as on solar generation.

Happy New Year!


"Things are as they are. Looking out into it the universe at night, we make no comparisons between right and wrong stars, nor between well and badly arranged constellations." - Alan Watts

* Don't worry, I won't subject you to the rest of these.
** December 22nd, the Winter Solstice.  See this rather impressive site to calculate the length of day in your city, for arbitrary dates going back and forward 20 years!
*** incidentally, this too is most likely a really bad idea.

1 comment:

  1. By the way, wind power has the same problems and the same solution: intermittancy and storage.

    Also by the way, you don't have to worry about storage when you're only making 2% of the total usage, because the power you make just gets cut out of the total made by other means. To understand why, consider this example:

    Say tap-water suddenly costs one dollar a gallon, so you can save money by supplementing your drinking water with rainwater. The easiest thing to do (assuming you're not squeezed for cash) is to drink rainwater when it was raining, and faucet-water when it wasn't. This would cut down on your faucet-water usage and save you a couple bucks. But if you want to switch entirely over to rain (say tapwater goes to 10$/gallon), you need to build cisterns and save up the water while its falling, because you're going to get thirsty on days when it's not raining too.

    If solar gets cheap and easy enough, we will see a substantial amount of electricity generated from solar power. To really make that transition, we'll need to build solar cisterns of some kind to save up sunshine for a rainy day.