PV Gap

Phillip Said:

Why is solar energy considered to be renewable energy?

We Answered:

Because the sun is going to come up tomorrow just like it did yesterday.

Margie Said:

Why we choose solar energy compared to other resources of renewable energy?

We Answered:

Most sources of energy renewable or not are from solar energy. Biomass is solar energy captured via photosynthesis and stored chemically. Wind power is from temperature gradient in the atmosphere due to heating from the sun. Hydro is from the evaporation of sea water and the subsequent precipitation at higher elevations. Fossil fuels are the solar energy captured by photosynthesis millions of years ago and stored chemically. All of these indirect methods of harvesting solar energy are very inefficient, photosynthesis has a maximum theoretical efficiency of 6.6%, then take into account that only a small portion of a plant is used for first generation biofuels and you can see that it's only a fraction of a fraction of 1% in efficiency. Contrast that to the current photovoltaic record of 42.8% efficiency

There are a few sources of "renewable" energy that aren't from solar energy. Nuclear energy is from the decay of radioactive elements left over from the formation of the Earth. Geothermal is heat from the molten core leftover from the formation of the Earth or from the melting of the tectonic plates as they move against each other. Tidal is from the kinetic energy of Earth's rotation and that of the moon's orbit. But these tap energy reserves much smaller than that of the sun.

You'll note that none of these energy sources are perpetual so "renewable" is a bit of a misnomer. But with the exception of fossil fuel, these are the sources of energy that tap energy reserves many times greater than can be conceivably consumed by us during a reasonable expectation for the life of our civilizations. At one time fossil fuels also appeared inexhaustible compared to our energy needs but then our energy needs increased.

If you look at how much energy is available, solar energy is available in quantities of up to 90 PW, that's peta-watts, at Earth's surface. Our entire global energy consumption peaks at 15 TW so solar energy is well in excess of our energy needs while indirect solar such as biomass, wind and hydro can in way theoretically meet our energy needs by themselves. Enough solar energy falls upon the Earth in 40 minutes to provide for the entire world's energy needs for an entire year.

Clifton Said:

Why is solar energy renewable?

We Answered:

Solar energy is considered renewable because it is a resource that will not run out, unlike oil, gas and coal. We can't actually use up all the solar energy because the sun keeps on shining and its energy will stay for us to use for a long time. Another example of a renewable resource is water. We will drink it and use it, but in the end it will just come back down as precipitation.

Kenneth Said:

Is solar energy a renewable reasource(this is from the june 2008 bio regent)?

We Answered:

and Coal is a fossil fuel??

Walter Said:

What makes SOLAR energy renewable?

We Answered:

wow, really? ok so you know the Sun? it doesn't burn out. we can use its energy. that doesn't lower its energy. BAM

James Said:

is solar energy renewable or non-renewable?

We Answered:

Renewable since the sun is not due to go out for at least 4 billion years.

The sun drives all weather on the planet so solar energy is not just that created in solar cells; wind energy is ultimately solar energy. Another way to use solar power is to heat water with it and then store the hot water for use; this is a common residential supplement that dates back to the 1970s.

I have seen this question before so let me give you a clue to answering it on other types.
- Any energy that requires fuel is non-renewable since we are not making fuel. That includes coal, natural gas, propane, gasoline, wood, even nuclear energy.
- Any energy that doesn't require fuel is a renewable resource; like wind, tidal, wave action, solar etc.

So where does geothermal energy fall; well we get it by pumping water into the ground and heating it. The earth isn't going away any time soon nor is the core cooling off so it can be considered a renewable resource. The earth will eventually cool off, but the small bit of energy we steal from it won't make much of a difference and chances are we will be long gone before the earth's core finishes cooling. Geothermal energy doesn't require any fuel so it is renewable. The earth's core requires radioactivity (which is fuel), rotational energy and pressure to keep it hot. The majority of the planet is hot we live on a thin crust so using geothermal heat is an excellent idea.