When I search "solar energy" and "chemical energy" on Google scholar, I get over 6,000 hits. When I limit it to "since 2015" I get over 1,000.

When do you expect any of these technologies will become industrially significant? Instead of units of time, please provide the answer in billions of tons of carbon dioxide dumped into the favorite planetary waste dump, our planetary atmosphere.

The rate at which we are currently dumping said waste into the atmosphere while we wait, like D'Estragnon waiting for Godot, is roughly 33 billion tons per year.

Seems each week there is a new "breakthrough" in solar energy. I'm 100% anti-fossil fuel and an early -and still- enthusiast about renewables. However, it is like standing on the railroad tracks looking out into the horizon for the train that you know will come some day, but not that day you're waiting, waiting and waiting.
It's like those remarkable leaps that you hear about in curing cancer or the things that inflict humans. The drums are beaten, the sound is heard, and then -- nothing .
Then again I'm getting more and more cynical as I age.

In particular, some of the work done in thermochemical processes, like high temperature pyrrolysis of biomass and carbon wastes, or high temperature hydrogen cycles. I just saw a very nice paper on the cerium oxide hydrogen cycles which the author proposed as a "solar" technology (even though it will never be economical in a solar setting owing to capacity utilization issues).

But overall the solar industry is a grotesque failure that does little more than suck trillion dollar sums out of the world economy without providing very much energy in return. After 50 years of jawboning about the topic, and trillion dollars of what has been represented as "investment," the entire solar industry, combined with the wind industry doesn't produce even 5 of the 560 exajoules that humanity generates each year.

I used to believe in so called "renewable energy", many years ago, but I have changed my mind. I oppose it entirely now, based on its toxicological profile, its expense, its unreliability, and the fact that it is only available to the rich at the expense of the poor, and because of the fact that it requires so much material, including not only common metals, but rather rare and rapidly depleting metals and other inorganic elements, that it is not, in fact, "renewable."

My opinion is that so called "renewable energy" will never be as sustainable, nor as safe, nor as affordable, nor as reliable as nuclear energy.

It's a crying shame, a disaster in fact, that humanity just doesn't get it. They'd rather burn oil, coal and gas to whine on the internet about a few atoms of Fukushima cesium in a Tuna fish off the coast of California than about the 7 million human beings who die each year, every year, constantly and without stop from air pollution.

That's a huge tragedy.