Though Tesla's (NASDAQ:TSLA) electric vehicles may not be all that green today, that doesn't mean they won't be an excellent means for sustainable transport in the future. From the raw materials going into the Tesla's batteries all the way to the sources of energy used to charge the batteries, Tesla CEO Elon Musk's bet on electric vehicles as a green alternative to internal combustion engine vehicles is largely a bet on new innovations tomorrow. And the other company Musk leads, SolarCity (NASDAQ:SCTY), may play a central role in this development.

Model S Twitter

Model S. Source: Tesla's official Twitter feed.

Battery production
All the way from raw materials to finished batteries, Tesla CEO Elon Musk claims to have a plan for a zero-emission process for battery production.

In Tesla's third-quarter earnings call Musk explained that it has acknowledged the fact that a "giga factory," or the world's largest factory for lithium-ion batteries, needs to be built. How else would Tesla ever produce an affordable car it could sell hundreds of thousands of per year?

But would the factory itself be green? Musk asserts that it will. Here are some tidbits he unveiled during the call:

  • There will be a lot of solar power.
  • It will have "essentially zero emissions."
  • Zero toxic elements will come out of the factory.
  • Battery recycling will be built in.
  • Just how big will the factory be? "[C]omparable to all lithium-ion production in the world in one factory."

Sounds pretty green, indeed. And considering Tesla has laid out a timeframe for the launch of its affordable car in 2016 or 2017, we won't have to wait long to see if Musk lives up to his word.

Solar power
Though the current sources of electricity in many areas of the world are far from green, typical sources like coal, natural gas, and nuclear plants won't always play such an important role as they do today in providing electricity. What will likely change the game? Solar power improvements.

Elon Musk, who is also the chairman of publicly traded SolarCity, recently shared an article that explains why he is bullish on solar power.

Summing up the article's most important arguments in two points...

  1. The annual energy potential from sunshine is about 25 times greater the total potential from coal reserves (and far greater than any other potential source).
  2. Prices for solar PV panels are falling rapidly. Prices dropped about 100 times over from 1977 to 2012 and 80% since 2008.

It would be naive for us to assume that solar technology for maximizing sunshine's potential energy will remain the same in the future. As solar charging improves and costs for the technology continue to fall, we may see exponential growth in solar PV capacity for years. Why not? The growth is already exponential. From 2007 to 2012, global solar PV power capacity grew 10 times over, according to the Renewables 2013 Global Status Report. 

The potential in solar is simply enormous. Steven Kotler, author of "Abundance", eloquently puts it into perspective:

The amount of solar energy that hits our atmosphere has been well established at 174 petawatts (1.740 x 10^17 watts), plus or minus 3.5 percent. Out of this total solar flux, approximately half reaches the Earth's surface. Since humanity currently consumes 16 terawatts annually (going by 2008 numbers), there's over five thousand times more solar energy falling on the planet's surface than we use in a year. Once again, it's not an issue of scarcity, it's an issue of accessibility.

Musk's big bet
The combination of new innovations in lithium-ion production and rapid improvements in solar charging innovations could very well make Tesla's vehicles far greener in the future than they are today. If solar power does improve by leaps and bounds in the coming years, will we look back at Musk's heavy investment into the two macro developments as well timed ventures in exploding industries? Possibly so.

This doesn't mean that both Tesla and SolarCity are automatically excellent low-risk investments. But accepting the fact that tomorrow will likely be far different from today will likely open up your mind to think differently about stocks that will be affected by solar power innovations in the future.

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Fool contributor Daniel Sparks owns shares of SolarCity and Tesla Motors. The Motley Fool recommends SolarCity and Tesla Motors. The Motley Fool owns shares of SolarCity and Tesla Motors. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.