We are living in a time when the theory of unlimited economic growth is running into the reality of limited energy sources. To solve the problem, it is commonly thought that renewables are simply a drop-in replacement for oil, gas and coal – but many experts are warning about the faultiness of that assumption.

Renewables offer less “net energy” than fossil fuels have historically delivered. That means they require more up-front energy (and financial) investment to procure a unit of energy.

We have grown our global economy on the assumption that we’d always have abundant energy. However, with renewables, which are less energy dense and more diffuse, we may have to re-evaluate our vision of growth, say some energy experts.

100 years ago, the energy return on energy invested (EROI) for a barrel of oil was 100 to 1. That means it took one barrel of oil to get 100 barrels out of the ground. Today, because companies need to go far deeper to get the resource, some estimates put the EROI of oil at around 15:1. Coal is at around 30 to 1 and gas is between 10-40 to 1.

Renewables like biofuels, solar, wind and geothermal range from 1.5 to 1 all the way up to around 18 to 1, according to various estimates. While the performance and net energy of renewables is improving, they still don’t match the historically-high energy density of fossil resources that we’ve come to rely upon for growth. This disparity between resources is sometimes referred to as “The Renewables Gap.”

In this podcast, we’ll have a look at the Renewables Gap and what it means for the length and complexity of the transition away from fossil resources.

We’ll start off with a surprising tale of an undergraduate student who uncovered an alleged conspiracy at the International Energy Agency to hide the peak oil problem. Lionel Badal talks about his adventures trying to alert politicians and journalists to the issue.

Then, Author, Activist and 350.org Founder Bill McKibben talks about what society will look like on this new “Eaarth” (as his new book is called) being formed by a changing climate and limited energy resources.

Energy expert and author Vaclav Smil gives us some historical context to the current energy transition. He’ll argue that renewable energy advocates are being unrealistic in their assumptions that we can switch to renewables in a very short period of time.

Author and Lawyer Jeff Vail talks about his worry that the Renewables Gap is not being addressed by politicians, energy companies or the financial community. Without a proper assessment of the net energy equation, he says, we may be setting ourselves up for failure.

Journalist and Financial Analyst Tom Konrad talks about why he’s a technological optimist, but a social pessimist. He’ll describe why a radical economic shift will be the only factor that forces the move to renewables and efficiency.

And finally, Jack Oswald, CEO of the bio-ammonia company Syngest, outlines his scenario of future “Energy Abundance.” He’ll lament the lack of vision we’ve shown in solving our problems related to energy.

Inside Renewable Energy is a weekly audio news program featuring stories and interviews on all the latest developments in the renewable energy industries.