Source: Forbes | Christopher Helman

It’s always a challenge to find a new set of nominees for Forbes’ 30-Under-30 list in energy. This despite the fact that the “energy industry” is quite likely the biggest in the world. According to the InternationalEnergy Agency, keeping the people of the world supplied with energy in all its forms costs about $1.7 trillion a year. (That’s double what we spent in 2000.)

It’s always a challenge to find a new set of nominees for Forbes’ 30-Under-30 list in energy. This despite the fact that the “energy industry” is quite likely the biggest in the world. According to the International Energy Agency, keeping the people of the world supplied with energy in all its forms costs about $1.7 trillion a year. (That’s double what we spent in 2000.) The vast majority, about $1.1 trillion, is tied to the extraction and combustion of fossil fuels, while roughly $250 billion a year goes towards renewable energy — up from $60 billion in 2000. Another $130 billion a year goes toward improving energy efficiency.

Despite the world investing four times more in “dirty” energy than “clean,” only five of our 30 work in the oil and gas business. Why is that? It’s a fair question, and one posed by our esteemed judge William Macaulay, the chairman of private equity giant First Reserve, who has over three decades invested tens of billions of dollars into energy extraction and infrastructure companies.

Why so few oil and gas guys? It’s a fair question. Foremost among the reasons is this: big oil companies that regularly invest billions of dollars on grand, complex projects do not rely on 20-somethings to make decisions. There are no doubt hundreds of incredible talents at the big oil companies, but in compiling this list we (and our panel of esteemed judges) are not just looking for young people with impressive job titles but for those who have shown entrepreneurial spirit and inventiveness.

That’s why among the few oil execs on the list this year you’ll find Grayson Lisenby, the CFO of natural gas driller Rice Energy, who helped the company raise $1.1 billion even before its $900 million IPO last year (co-founder Derek Rice appeared on last year’s list).

Outside of oil and gas, most of the members of this list have helped found renewable energy companies — and are working to capitalize on brilliant ideas, often without much financial capital.