Hopefully it’s the part that people aren’t parking on. I mean, no one is crazy enough to put solar panels in a place where they’ll be covered up for 8 hours every day, are they?
A lot of the cheap land is used for agriculture or is wooded. The median strip is just wasted space with few trees on it and easy access. Seems to me we could kill two birds if we put something useful there. But I’m not a civil engineer or anything, so I dunno.
It’s also very spread out, with access roads, culverts, guardrails, and other stuff in the way. Solar panels in solar farms tend to be clustered around heavy duty transmission equipment for efficiency, and the closer they are to wherever the power will be used, the better. It just doesn’t make a lot of sense to string them out along highways where nobody lives.
Farmland is less than $5k per acre in most places. For any solar project in the midwest, land cost is going to be negligible.
Which is a sad statement on our scientific literacy. Anyone who understands high school physics should realize that tractors with huge tires exert much less stress (less pressure) on the road than vehicles designed for highway use.
This.
You’ve got the whole DC vs AC business, and the need for collection facilities and then transmitting the power to places where power is used. My electrical knowledge is next to zero, but even I can see the need for expensive ifrastructure to transmit very tiny amounts of power.
~VOW
Why not instead put solar panels above the cars in the parking lot, so they’re never covered and they provide shade to the cars?
Drivers on the south side of the panels might be bothered by sunlight reflecting off the panels. Drivers on the north would have a flickering effect as they drove through shafts of sunlight coming through the gaps between the panels. And unless the median is very wide, they’d have to shut down a lane of traffic to do any serious maintenance on the panels.
Nevada National Guard did this. Kills two birds with one stone.
Lots of businesses and government offices in Clark County, too.
Is the idea of solar roadways a failure of science education, of critical thinking engineering, or a triumph of the con man?
Because, as noted, thirty seconds of thought shows what a stupid idea it is. So why does it persist?
It’s like Theranos.
There are plenty of medians wide enough to do maintenance as they are wide enough to have vehicles on them already to do other sorts of maintenance. You probably couldn’t get much electricity on inaccessibly-small medians anyway.
I’d say most divided highways have a large enough median, of those that have medians. Most of the median on medium-sized medians might be taken up by buffer space for said maintenance, but not all.
Sure. And bicycle tires, often inflated to around 100 psi in the case of road bikes, exert the most of all.
But do you think more wear is caused to road surfaces from static pressure exerted from above, or from the lateral forces exerted by vehicles accelerating, decelerating (especially braking, which can literally leave a mark), and turning? How about when defects form on the surface (pot holes and dips) and a larger than normal portion of the weight slams down?
I’ve seen enough medians where none of these would be issues. But what would still be an issue is when an accident involving crossing the median in BFE, which would then never get fixed.
The pressure referred to was not the inflation pressure of the tire, but the pressure exerted on the ground which due to the very large contact patch of tractor tires is typically lower psi for a tractor than it is for most road-going vehicles. Tractors are specifically designed to not sink into the relatively soft dirt of fields, after all.
“Wear” due to acceleration isn’t really the big issue as far as pavement is concerned, it’s the bending stress from transient vertical loads, which causes the entire thickness of pavement to flex as the load moves over it. And when it comes to vertical loads, it’s hard to beat trucks. 80,000 pounds divided by 18 tires = 5000 pounds of load per tire. Compare to (at most) 1000 pounds per tire for a full-sized passenger car. There’s a long-established rule of thumb which says that damage to the pavement scales with the fourth power of tire load. In other words, you can expect a truck tire to cause 625 times as much damage to pavement as a car tire. Throw in the fact that a truck has 4.5 times as many tires, and it means that a truck causes about 2800 times as much damage to the pavement as a car.
A bicycle tire may have the same pressure in it as a truck tire, but since it’s only carrying ~100 pounds of load, it hardly causes any flexing of the pavement at all.
Thank you for offering up that explanation. To be clear, I’m not the one who sought to equate pressure alone with stress.
Yeah this is another thing I’ve wondered a lot. I think I’ve seen one or two parking lots do this, but in my totally non-expert opinion, it would seem to be an opportunity to generate a lot of electricity. Turn those acres of parking lot in the average mall into a solar farm. I have no idea of the economics involved, though.
The economics aren’t great it most places, which is about 99% of the problem. We had a solar panel company try to sell us on rooftop solar here in central Ohio, and based on the current (low) energy prices due to fracking and the limited southern sun exposure that comes with being at 40 degrees latitude, even they couldn’t get us a ROI under the lifespan of the solar panels. They basically shrugged and left, and nearest I can tell abandoned the idea of a central Ohio market altogether.
Basically the business case for solar in America is strongest in the Southwest where the question of “where do we put these solar panels” isn’t really a question at all – finding some empty desert land next to a population center is as easy as a throwing a rock.
Are my taxes paying for this shit? If NASA is buying, that suggests they are. :smack:
Yeah, but where’s the potential for hype (and all the sweet sweet money derived from it) in that?