CAPTURING FLORIDA’S SUNSHINE

Dave Trecker

As energy sources go, you can’t beat the sun. Its rays have enough quanta to heat the earth and generate power for the geologic future, and that means forever. It’s up there, it’s constant, it’s inexhaustible.

Although only one-billionth of the sun’s power reaches the earth’s surface, that’s more energy in one hour than all of the energy consumed by humans in an entire year.

How much of that energy is available to Florida? We’re not the sunniest state (Florida ranks either 6th or 8th, depending on how you measure it), but on average 2/3rds of the sun’s rays reach the ground here during daylight hours. That’s a lot of free energy.

How well do we capture it? Not very. Conversion of solar quanta to electrical power is very inefficient, between 12-22%. As a result, Florida’s utilities generate only a few percent of the state’s electricity from the sun. Most comes from cheap natural gas. There’s little incentive to switch; Florida electricity is among the cheapest in the nation.

There are three interrelated problems with photovoltaic energy and particularly with solar farms:

• They are inefficient and costly.
• To make them cost-competitive requires investment credits and taxpayer subsidies.
• They have a massive footprint. Unlike coal, natural gas or nuclear power plants, they take up vast amounts of land. To power all of Florida would require solar farms covering some 20% of the state.

On top of those problems, solar has an inherent disadvantage. The sun doesn’t shine all of the time. When it doesn’t, the energy has to come from somewhere else. That means investment not just in solar farms, but in gargantuan storage batteries or in backup fossil fuel plants.

Rooftop use avoids some of those problems. With hefty subsidies available, capturing the sun on-site makes economic sense, particularly for large retail centers, warehouses and flat-roof factories – many backed with “powerwall” batteries that can store up to 15 kWh for later use.

The electricity is generated on the spot, where it’s needed, without loss in power lines or dependence on the grid.

Innovations have brought solar to city high-rises as well. “Smart” windows are now available with dye-sensitized solar cells that generate electricity for the room.

But this is just nibbling at the edges. To take full advantage of the sun’s power, photovoltaic power must become a large part of the grid. That means significantly improving efficiency, enough to obviate the need for subsidies and reduce the huge footprints of solar farms. And that, in turn, means technical breakthroughs. And they’re coming.

Perovskites, low-cost organometallic crystals fashioned into tandem photovoltaic cells, have achieved 28% efficiency and conversions of 30-35% are within reach.

Still cheaper materials, low-cost organic photovoltaics, capture a wider spectrum of the sun’s rays and offer the potential for even greater savings. If durability problems can be overcome, either type of cell would make solar a major player.

Battery improvements are coming at an even faster pace. Lithium batteries are being upgraded. Scarce cobalt is being replaced. New liquid electrolytes are being piloted. Chemical flow batteries are in advanced stages of development. Lighter, cheaper batteries with more capacity and longer lifetimes are within reach.

It’s not a matter of whether, but of when. This bodes well for solar power. But there are also other ways for Florida to use the sun.

One is to target agricultural production. How about inserting phototropins into field crops to boost yields? Or generating plant based biofuels by genetically modifying canola seeds?

Another is to use the sun to manufacture chemicals. Detergents, refrigerants, herbicides and other products could be produced photochemically. And everyday plastics could be made by sun-induced polymerization in factories with retractable roofs.

There’s no end to the possibilities. We’re just beginning to scratch the surface. And that’s good news for The Sunshine State.