Famed inventor Thomas Edison brought us electric lights, phonographs, movies, and even the first research and development laboratory.

But in 1931, he also was one of the first promoters of renewable energy - especially solar.

That year he described our approach to energy to two industry magnates of the day - Henry Ford and Harvey Firestone.

He told them "we are like tenant farmers chopping down the fence around our house for fuel when we should be using nature's inexhaustible sources of energy - sun, wind and tide."

That was over 80 years ago - and we're still living the same way.

In 2014 - just over 13% of American electricity production came from renewables in some form or another.

That's not terrible - but it means that we're still getting nearly 90% of our electricity production from "chopping down the fence around our house for fuel".

And if the fossil fuel companies, lobbyists, and the 21st century fossil fuel tycoons (like the Kochs who inherited their oil company from daddy) have their way, that's not going to change anytime soon.

They're still fighting for ways to bring Alberta's tar sands to America to be processed and burned - and they're still chomping at the bit to drill in the Arctic's deep seas.

They're even using our precious fresh water reserves to shatter our Earth's shale just to get to the natural gas - making the Earth unstable and much of our water poisoned in the process.

Even as we run out of fenceposts to burn - the fossil fuel barons still point to more of our farm's property to chop down and burn.

Edison even gave Ford and Firestone a little bit of investment advice to go with his criticism - "I'd put my money on the sun and solar energy. What a source of power! I hope we don't have to wait until oil and coal run out before we tackle that."

Unfortunately - the fossil fuel companies don’t have any interest in folding up operations and letting our 19th century energy regime join the likes of whale-oil lamps as a historical curiosity.

But according to a new report from Citibank, large-scale investments in renewables are still a smart investment move for both the planet and the global economy.

The report is called "Energy Darwinism" and it looks at the predicted cost of energy over the next several decades - compared to the costs of developing and implementing low carbon energy sources.

And then the researchers looked at the implications of global energy choices in terms of expected climate impacts.

The bottom line?

If we invest in low-carbon energy sources now - like solar, wind, tidal and geothermal - the global economy would save $1.8 trillion through 2040.

And the cost of inaction? The cost of carrying on business as usual? The cost of trying to adapt to the negative effects of climate change instead of reducing the risks by transforming our energy system?.

Well - that could cost as little as $20 trillion - or as much as $72 trillion.

And that's a decrease in global GDP of between .7% and 2.5%.

In other words - we can expect a global economic contraction if we continue to rip our carbon reserves out of the earth and burn them into the atmosphere and we don't reform our global energy system.

Or, through investing in a mix of renewables while reforming our energy system, we can avoid many of those costs and grow the global economy by $1.8 trillion.

The thing is. This isn't really new information. This is basically just a reiteration of the 700-page Stern Review, which pointed out back in 2006 that strong early action on climate change will save money for the global economy in the long run.

It's been nearly a decade since Sir Nicholas Stern concluded that taking bold action sooner rather than later will save money and ultimately grow the global economy.

And in the meantime, the status quo fossil fuel interests have funneled money into researchers willing to lie for a paycheck, while they've fought responsible reporting on climate change in the corporate media, and they've bought our politicians.

All to make sure that people think that climate change isn't real, and that people think that fossil fuels are more affordable than renewables.

But that's not what the bankers - the economists - or the scientists say.

Just back in June, a team of researchers from Stanford and U.C. Berkeley published research showing how every state can go 100% renewable by 2050.

And they showed that the states would save money and create jobs by doing it.

We've ignored Edison's words to Ford and Firestone for far too long.

It's time to stop burning our fence posts for fuel - it's time to tap the Earth's inexhaustible sources of energy in the nuclear fusion reactor 93 million miles away that we call our Sun.