Green hydrogen has generated a lot of interest as a zero-carbon or low-carbon fuel. Its ability to be injected into existing natural gas infrastructure has led to several large oil and gas companies promoting its use to preserve their existing pipeline assets while lowering emissions. However, despite all the hype surrounding green hydrogen, Clean Energy Group has found that there are several reasons to be concerned about its use, particularly in power plants. While hydrogen might have a valid role to play in deep decarbonization of the heavy transport or industrial sectors, runaway plans to use it extensively in the power sector have the potential to jeopardize the health of environmental justice communities, not to mention renewable energy goals. This fact sheet outlines five reasons to be concerned about green hydrogen.