There’s a battle brewing between the titans of renewable energy and fossil fuels.

Robert Murray, the CEO of America’s largest coalmining company Murray Energy Corporation went on the offensive Monday, accusing Tesla Motors of taking tax subsidies from the federal government while not turning out a profit. Tesla’s CEO and founder, Elon Musk, was quick to respond.

Tesla has “gotten $2 billion from the taxpayer, has not made a penny yet in cash flow,” Murray said on CNBC’s Squawk Box, calling Musk’s company “a fraud.” “Here again: it’s subsidies,” Murray continued.

Musk — whose company doesn’t actually receive direct government subsidies but instead receives “carbon credits” that it sells to other companies that don’t meet carbon emission standards — took the bait and upped the ante.

The “real fraud going on is denial of climate science,” Musk wrote on Twitter. “As for ‘subsidies’, Tesla gets pennies on dollar vs coal. How about we both go to zero?”

The coal industry receives much more cash from the federal government every year than Tesla does. The last time the electric car company received any “handouts” from the government was in 2013 when they received $465 million as a part of the auto industry bailout. The coal industry, in contrast, receives billions of dollars in subsidies from the taxpayer every year, an investigation by Think Progress found.

It is true that Tesla has yet to turn a profit. Just last month, Musk reportedly told his employees in a companywide memo to “deliver every car we possibly can” and slash costs in order to finally turn a profit. The issue has been a real concern for Tesla, which has seen its stock drop 16 percent this year as Wall Street critics have wondered whether they will ever be able to actually bring in a profit.

“It would be awesome to throw a pie in the face of all naysayers on Wall Street who keep insisting that Tesla will always be a money loser!” Musk wrote at the time.