PV Gap

Andrea Said:

what are the cons for coal,natural gas,hydroelectric,geothermal,hydrogen,f… cell,wind,nuclear,and,solar?

We Answered:

coal produces CO2 and global warming/ fumes that create air polution(mercury and such) it is also a fossil fuel, meaning that it cannot be renewed

nuclear produces nuclear waste that can be made into weapons although we now have technology that can use 99% of the fuel and the remaining waste will be of such low grade not even a dirty bomb can be made. This is promising for nuclear power since it lasts the longest and is highly productive

solar is that the panels take up lots of space and that space would be unusuable for anything else(solar fields)

geothermal is that it can be only placed in certain areas and fumes from the inside of the earth such as Hydrogen Sulfide have to be taken care of otherwise air polution will result.

wind is that there is no constant wind, you have to sit and wait for the wind to come, these also take up lots of space but technology has made it even more efficient

hydroelectric energy is that dams damage the enviroment, fish cannot migrate upstream as a result, and tidal versions are still in development.

i think you might have wanted to say fuel cell so ill answer anyway- fuel cells (hydrogen) currently take more energy to create the hydrogen than the energy the hydrogen can actually release, GM is currently testing wind as a potential energy generator for the hydrogen to be split from water to make hydrogen fuel, however hydrogen technology has become more efficient, currently some machines can generate 70-80% efficiency

natrual gas is abundant, but there are risks such as explosions involved, it also releases greenhouse gasses such as CO2 when burned although it is cleaner than gasoline and desiel when properly used. like coal natrual gas is also unrenewable since it too is a fossil fuel

Catherine Said:

Are you confident that we will ever be driving fuel cell cars with solar generated hydrogen.?

We Answered:

Never happen.

It's easy enough to make hydrogen/oxygen from electricity, and that's great news for welders and other folk.

But using hydrogen in a car, you hit two very nasty technological walls.

First is turning hydrogen back into electricity. This is very hard to do efficiently, and even harder to do cheaply.

Second is compressing the hydrogen enough to fit a decent supply onto an automobile. It just takes way too much energy, and I see no way around that. It only works if energy is cheap. If energy is not cheap, it's a total lose.

Bottom line, if the goal is to store energy from the grid on a vehicle for propulsion, there are better ways to do it. Heck, one of them was invented by Thomas Edison.

Javier Said:

what is the best way to measure the efficiency of a fuel cell?

We Answered:

There are 4 sources of efficiency here: the solar cell, the electrolyzer, the fuel cell and the fan (also the propeller if you want to consider that, too). The easiest way to determine the total effeciency would be to measure each one individually and multiply the efficiencies. There are a lot fo equations for all of this, but basically you would need voltmeters for the solar cell and fuel cell, an ampmeter for the motor, a calorimeter or gas chromatograph for the fuel cell, and a wind speed detector if you want to measure the fan's efficiency.