Kömür ve doğal gaz doğal yakıtlardır.
- Coal and natural gas are natural fuels.
Hidroelektrik yenilenebilir bir kaynaktır ama petrol, kömür ve doğal gaz değil.
- Hydropower is a renewable resource, but oil, coal and natural gas are not.
Natural-gas prices.
... to make it a priority for us to go after natural gas. We've got potentially 600,000 jobs ...
... from 40 to American natural gas ...