This involves a rather large chunk of traditional fuel usage.
On average, the federal government consumes about 2% of the fossil fuels used in the United States - and the DOD accounts for about 90% of that.
With the Obama administration emphasizing a move to alternative and renewable fuel sources, Mabus is signaling that the military is on board - sort of.
The Trouble with Foreign OilAs a former governor of Mississippi and ambassador to Saudi Arabia, Secretary Mabus knows something about the position of oil in American foreign policy.
He noted during the conference that, for every $1 rise in the cost of crude oil, the Navy has to come up with at least $32 million.
So when the Libyan crisis hit earlier this year, and oil spiked $30 a barrel, that translated into almost $1 billion of additional costs to the Navy. It's no wonder, then, that Mabus is committed to meeting 50% of the Navy's onshore and fleet fuel needs with non-fossil sources by 2020.
Additionally, in what is now mantra from both sides of the political aisle, reliance on foreign oil sources presents a national security problem.
"When we did an examination of the vulnerabilities of the Navy and Marine Corps, fuel rose to the top of the list pretty fast," Mabus said. "We simply buy too much fossil fuel from actual and potentially volatile places. We would never allow some of these countries we buy fuel from to build our ships, our aircraft, our ground vehicles - but because we depend on them for fuel, we give them a say in whether our ships sail, our aircraft fly, our ground vehicles operate."
The push seems serious enough, and it does reflect similar statements coming from other branches of the military.
But questions remain: What are the alternative sources? How much volume can each genuinely give to the effort? And what are the possible drawbacks of such alternatives?
Biofuels to the RescueFrom the Navy's perspective, biofuels have shown some serious promise.
In certain theaters of operation, bio additives are already in use for both jet fuel and lighter vessel options. And the initial results have been quite encouraging.