Fusion is always “x years away,” or so goes the old joke. I tried (unsuccessfully) to find where this saying even came from.

For what it’s worth, one researcher’s testimonial dates back to the 1960s, whereas another 1986 conference panel mentioned something similar. Both accounts say fusion power is 50 and between 25 and 30 years away, respectively, so that adds up to around the 2010s.

Clearly, we’re well past this so-called deadline and still getting headlines about how fusion energy is 30 years away or 50 years away or, for the mathematically minded, maybe 17.8 years away. So the joke quips at the apparently sluggish pace at which fusion energy is arriving to commercial grids. But this comes with important caveats. In the past couple of decades, there have been huge strides in fusion research, leading to increased energy outputs, improved hardware, and a wide range of experimental and theoretical developments—coming from big and small stakeholders from around the world, too. And scientists have achieved fusion ignition in labs.

The question isn’t so much whether humans can recreate how stars fuel themselves on Earth, but more the question of how we can do that consistently, continuously, and efficiently.

We posed the latter question to experts for this Giz Asks. No need to take a shot at guessing when fusion energy will arrive. No need to justify the value of fusion research. But if fusion energy isn’t here yet, there has to be a reason (or two or three). And we should probably get on top of that, right? So, what are these reasons? If one had to pick the greatest obstacles for fusion power, what would that be? And, most importantly, are there any easy solutions?