Gas turbines are able to utilize a wide variety of fuels, including fuels with low- or zero-carbon content. This includes hydrogen (H2), ammonia (NH3), synthetic and renewable natural gas, as well as a range of biofuels. These are sometimes referred to as zero-carbon, net-zero-carbon, or near-zero-carbon fuels. A subset of these fuels have been used to produce power from gas turbines for decades. This chapter will review experience and practical challenges in the use of these fuels in gas turbines for power generation applications, describing case studies for utilizing these fuels in the field.