House Speaker Nancy Pelosi, a Democrat from California, defended her investment in T. Boone Pickens’ Clean Energy Fuels Corp. during an appearance Sunday on Meet the Press by saying she is investing in something she believes in.

T. Boone Pickens is spending $58 million on his national marketing campaign to promote alternative energy sources like wind for electricity and natural gas for cars. In the two weeks since he announced his effort, the stock market value of his company that supplies natural gas for vehicles has increased by about twice that amount.