2. If using heating elements was cost efficient to keep ice off, you can bet the military and civilian airfields would use it to keep the runways clear. They do not. My father used to work at an Alaska military airbase, he said that snow and ice removal on the runway was a 24/7 operation. They weren't fools, if the heating element idea would work they'd have used it.
Not that they provided any actual data for us to tell if it is impossible or not.
Edit: hell, they don't even make a cost comparison to putting regular old solar panels next to the road, instead of baked into the road, and using the energy from that to do whatever fancy shit.
The only difference is that the top layer is glass rather than concrete / asphalt.
More importantly, there is no reason the roads couldn't draw energy from the grid at times. Being subject to snow is very different from 24x7 snow all winter. If it is providing energy 80% of the time and drawing 20%, it may still be a net positive, especially when combined with enhanced safety and removing the winter maintenance budget line items (well, reducing, anyway).
Plants store solar energy as hydrocarbons. Further reformed into coal, oil, and gas, that's what we use today.
It's possible to synthesize hydrocarbons from seawater at a net efficiency likely around 50%. Hydrogen electrolysis is the primary energy cost at 60% energy delivered on input.
Run that from solar cells at 20% efficiency and you've got a net delivery of 10% of input solar as stored hydrocarbons. Mind that you're only going to extract about 30-40% of that as useful work or energy (electric generation is about 38% efficient in fuel conversion, cars around 10-20%, IC engines generally about 30%).
But the neat thing about hydrocarbons is that once you've got them, they can store for a long time. Hell, we've got proofs-of-concept showing 300-500 million year viability.
There are other options as well. Some are far more responsive (flywheel kinetic storage, pumped hydro), some far more efficient in energy input/output), others have varying degrees of suitability (CAES, thermal energy storage, liquid metal/molten salt batteries). I'm actually starting to see this as a potentially solved problem.
"False Claim: we can't afford to heat roads"
Their response doesn't actually talk about the feasibility of heating roads. They don't mention how much energy their solar panels will have stored before a snow storm, and whether or not it would be sufficient to melt lots of snow.
My half-assed guess is that there's maybe enough energy in theory to melt an inch or two of snow, but they don't really provide sufficient detail:
(From their website):
"Currently, the full size hexagons are 36-watt solar panels, with 69-percent surface coverage by solar cells. This will become 52-watts when we cover the whole surface when we go into production. When we add piezoelectric, they'll be capable of producing even more power. Also, as the efficiency of solar cells increase, more power will be converted.
We tested the heaters over the winter with a DC power supply that provided them with 72-watts. This was an overkill and made the surface warm to the touch on most winter days. We still need to experiment with different voltages at different temperatures, to determine the minimum amount of power required to keep the surface above freezing. Remember, they don't have to heat up to 85 degrees like the defroster wire in the windows of your car: they only have to keep the surface warm enough to prevent snow/ice accumulation (35 degrees?)."
You need what, like 300 Joules to melt a single gram of ice/snow/etc. So their 50W panels could melt a gram of water per 6 seconds.
I can't figure out how big the panels are, but their website seems to say 4 square feet. So each 2'x2' square area (hexagon, whatever) can melt 0.166 grams of ice/snow/etc per second.
Say you get a hypothetical snowfall of 2" (not very damn much for some areas). That's 4 ft * 2 in of snow, or 2/3 of a cubic foot. That's about 10 pounds of water in solid form, or 4.5k grams. So assuming their 50W panels are 100% efficient at melting snow, it would take their accumulated energy about 8 hours to melt the snow. (Of course please check my math, I might be off by an order of magnitude on either end here)
That seems at least theoretically possible, but there's no discussion about how much energy a panel can store, or other factors that would weigh in here. There's no actual technical discussion whatsoever for that matter. So I was kind of disappointed by the article.
Edit, sorry: 'It would take their panels about 8 hours to accumulate the energy necessary to melt 2" of snow' (That's at least somewhat in the realm of possibility, though for many areas 8 hours of direct sunlight during the winter ain't happening, and a guarantee of a max of ~2" of snow in a day also ain't happening)