That's a compelling idea. I've seen systems that use essentially solar panels on the roof that heats up a liquid in a loop then goes to a heat exchanger which heats up your water before it goes to the water heater, thus making it so the water heater doesn't have to work as hard.
Could we use the exhaust from your fridge, A/C, furnace, etc. to also heat coolant in a similar system that circulates to your pre-water heater, thus boosting efficiency. Especially if you can dump the exhaust of your fridge outside rather than paying to heat up that air, then cool in down again with your A/C.
The question is if the cost savings would be worth the cost of the system.
The closer you get to the equator, the more you're likely to see these. When I was visiting Turkey, I didn't notice them in Istanbul because most rooftops are not visible from the street, but then I visited Safranbolu, a small tourist town, and there almost every century home had this recently-made metallic hot water tank on top which completely destroyed the bucolic architectural character of the town.
One of my uncles here in Canada built a passive system by just putting a giant 1" PVC tube coil on the backside of his roottop to heat up water for the swimming pool, since the swimmable season is pretty short anyway.
Not sure if it’s exactly what you’re talking about, but something similar is pretty common in China as well. I’ve heard people call the system “solar power“, but what they’re referring to is effectively a tank of water on the roof that is heated by the sun which is used as the hot water source for showers, etc.
> The question is if the cost savings would be worth the cost of the system.
I think it might be, if it was built into the home from the beginning, and the engineering cost was spread out over a large number of units. In other words, I don't expect it to make sense for one homeowner to retrofit their house.
It would make more sense in a condo/apartment/multi-unit/commercial situation.
I would agree, with the caveat of "all else being equal". There is a danger in ignoring vast socioeconomic divides that can put people at a disadvantage that can make things more difficult for certain demographics.
The earth is orbiting the sun at 30 kilometers per second. So if we launched something into space, since it started on earth, it would have that speed (similar-ish to throwing a ball from a moving car). So that object would now also be orbiting the sun at 30 km/s. We would need to slow it down that much in order to "fall" into the sun.
Once something was in earth orbit, it would only take about 12 km/s of delta v (change in velocity) to escape the solar system.
Although you could do it with about 17km/s if you put it into a Holman transfer orbit to Venus and used a low flyby and aerobrake maneuver of Venus and that puts you into a flyby of Mercury which changes the orbital plane such that the ellipse intersects the corona.
Sad note that also limits your launch window to once every 113 years as I recall from the last time I did the math :-(.
From a technical perspective you push into an elliptical orbit that intersects Venus, you do a slight aerobreak (skim the surface of the atmosphere) to dogleg toward a Mercury intercept, and then as you pass Mercury it tightens your ellipse still further and you head out, and come back and fly through the outer corona of the Sun (which is its hottest point). At which point you're in a degenerate orbit that will go out and come back through the Sun's corona until you've been completely consumed/burned up.
Why do you have to slow it to 0 to hit the sun? Can't you just cruise at whatever speed you're cruising and redirect it with thrusters towards the sun?
In space (and any frictionless medium), you can't "redirect" an existing velocity vector with thrusters. You can only add a velocity vector. This means that if your desired direction is perpendicular to your current direction, your current speed is no good to you at all. If you're heading due "north" at 10mph, and you want to be heading due "east" at 10mph instead, you have to 1) fully negate your "north" velocity, and 2) come up with 10mph of "east" velocity from scratch.
Now, the trajectory of an object in solar orbit is exactly at right angles to the direction it needs to go in to hit the sun. No part of this velocity is helpful for getting to the sun - in fact it actively prevents it! The only vector that takes you directly into the sun is one with no sideways component - if you imagine yourself falling right in, any sideways nudge will cause you to miss it by a hair and go flinging off into a highly elliptical orbit. If you just ignore this and just thrust directly at the sun, hoping to overpower everything by brute force, then like a ballerina pulling her arms in, the more you try to get close to the sun with your thrusters, the faster your orbit will go; the closer you manage to get, the further out you'll be flung when you inevitably miss.
All this ignores that the sun is not a point, but quite a large ball - you can get away with some small horizontal velocity. A highly elliptical orbit will still do what you want if its lowest point is below the surface.
Once you're in orbit (say around the sun), you have to cancel the orbital velocity to fall into the object you're orbiting around. If you point at the sun and accelerate 1 km/s directly at it, you're still moving 30 km/s "sideways". All you'd end up doing is making the orbit more elliptical-shaped.
At least that's how I see it, but I am far from being an authority on this topic.
Thanks, I actually have it installed, but never made it through all the tutorials. I'll probably give it another shot, would make it much easier to get an understanding of simple questions like this one.
I'm no rocket scientist but perhaps that would cause the object to shift from the Earth's kinda-circular orbit into a highly-elliptical orbit, its existing sideways velocity (relative to the sun) causing it to be flung past the sun at more of a straight line and hence way out into the solar system instead.
Context is important. Pretty much the entire aerospace industry is terrible at time estimates. SpaceX has accomplished some incredible things, so bashing them for "the whole Mars thing" when they are still hard at work on it seems premature and pithy.
And as far as I'm aware they never promised a 30k car? They promised a 35k car, which you can buy today (you just have to email them or go in person and ask for it, it's not available online)
To me "compost" is a decomposing pile of natural materials. Plants, certain types of food waste, animal waste, etc. that anyone can put in their backyard (or scale up to industrial size) to turn waste into nutrient rich soil.
A very specific industrial process that can break down a very specific type of material in just the right circumstances is so completely different that it seems odd to me to share the same name.
