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I implore people to support something far more practical like http://www.solar-aid.org/ than this. Solar lights are many times more thermodynamically efficient, cheaper to make, smaller and much more robust (no moving parts!). This "lifting weights" thing is a silly gimmick. A lifted weight stores a miniscule amount of energy compared to a battery that's been charged by the sun.
I implore people to support something far more practical like http://www.solar-aid.org/ than this. Solar lights are many times more thermodynamically efficient, cheaper to make, smaller and much more robust (no moving parts!). This "lifting weights" thing is a silly gimmick. A lifted weight stores a miniscule amount of energy compared to a battery that's been charged by the sun.
Earlier quoted context omitted.
So by your logic fossil fuel is solar energy.
It is. Except for geothermal energy brought on by radioactive decay, all energy on earth originally comes from the sun. Fossil fuel is sunlight that was absorbed by plants which then either decomposed into fuel over millions of years, or were eaten by animals which later decomposed into fuel over millions of years. Our cars are powered by very old, stored sunlight.
I implore people to support something far more practical like http://www.solar-aid.org/ than this. Solar lights are many times more thermodynamically efficient, cheaper to make, smaller and much more robust (no moving parts!). This "lifting weights" thing is a silly gimmick. A lifted weight stores a miniscule amount of energy compared to a battery that's been charged by the sun.
There's a lot of reasons why this is cool, but I'm skeptical about it's aims to get rid of kerosene lamps. Kerosene lamps are made with garbage. They can be replaced in minutes if there's a problem. Fuel costs are high, yes, but capital costs and maintenance are low. Those matter. To really make this a long term win, you need to make it indestructible and easy to repair with on-hand parts. I hope they can do that.
I implore people to support something far more practical like http://www.solar-aid.org/ than this. Solar lights are many times more thermodynamically efficient, cheaper to make, smaller and much more robust (no moving parts!). This "lifting weights" thing is a silly gimmick. A lifted weight stores a miniscule amount of energy compared to a battery that's been charged by the sun.
Earlier quoted context omitted.
It is. Except for geothermal energy brought on by radioactive decay, all energy on earth originally comes from the sun. Fossil fuel is sunlight that was absorbed by plants which then either decomposed into fuel over millions of years, or were eaten by animals which later decomposed into fuel over millions of years. Our cars are powered by very old, stored sunlight.
And radioactive elements come from long dead suns, so all energy on earth originally comes from A sun.
Years ago there was a similar 'potential energy to electricity' buzz and I was initially quite excited. Then I did the math on how much energy is actually available (even at 100% efficiency) from such a scheme. Spoiler - it's minuscule. E = mass x 9.81 x height So a 10kg mass at 2 meters can (@ 100% efficiency) provide 196 joules of energy. A modern cell phone battery has about 25000 joules. To charge said phone woul…
You could theoretically have something like a 1000kg mass which was lifted through a series of pulleys...
I implore people to support something far more practical like http://www.solar-aid.org/ than this. Solar lights are many times more thermodynamically efficient, cheaper to make, smaller and much more robust (no moving parts!). This "lifting weights" thing is a silly gimmick. A lifted weight stores a miniscule amount of energy compared to a battery that's been charged by the sun.
Beyond the "no moving parts" (and maybe cheaper to make), I think you're just spilling a marketing blurb.
> This "lifting weights" thing is a silly gimmick. A lifted weight stores a miniscule amount of energy compared to a battery that's been charged by the sun.
Potential energy = m.g.h So, lifting a 10kg weight at the height of one meter gives approx. 98J
Incident solar power is 100W/m2 (best case). A square solar cell 10cm of side hence gets 1W (or 1J/s), after efficiency losses this is even less (which are present on the GravityLight as well). Between 0.5W and 5W seems common on sale websites
So, lifting the weight above (which takes 1s approximately) gets you as much energy as 36s of solar energy (of course, you can't recharge it at night)
Also consider the cost of the battery
Edited for wrong math
I implore people to support something far more practical like http://www.solar-aid.org/ than this. Solar lights are many times more thermodynamically efficient, cheaper to make, smaller and much more robust (no moving parts!). This "lifting weights" thing is a silly gimmick. A lifted weight stores a miniscule amount of energy compared to a battery that's been charged by the sun.
The weight option has the benefit of durability. A battery needs to be replaced after x charge/discharge cycles. The goal of GL is to reduce poverty cycles by making a one-time investment that pays for itself in a month. Adding the recurring cost of a battery, even if still cost effective, runs counter to that goal.