So basically they developed nothing exactly new, but went back to the roots. The article mentions:

"The development of a new fossil-free iron product (sponge iron) that has significantly better properties than iron reduced with fossil gases[...]"

So i looked up sponge Iron. Wiki writes:" Producing sponge iron and then working it was the earliest method used to obtain iron in the Middle East, Egypt, and Europe, where it remained in use until at least the 16th century."

I was also curious which properties are meant, but only found them for wrought Iron, which is made from sponge Iron, because sponge Iron itself can not be used. Also Wiki: "Wrought iron is tough, malleable, ductile, corrosion resistant, and easily forge welded, but is more difficult to weld electrically."

So in sum they went back to OG ironmaking and now seem to have higher quality stuff. Very nice.