"People who work on photovoltaic power generation, and people who work on controlled nuclear fusion." Song He revealed the answer.
The students pondered this.
"Controlled nuclear fusion. I think Lu Geng figured it out. Earlier, you said the two major energy sources humanity could utilize were, first, the sun, and second, nuclear fusion." Song He said,
"To increase income, there are only four words: increase revenue and reduce expenditure! All humanity can do right now is reduce expenditure, trying every possible way to waste less of the sunlight that reaches Earth. Nuclear fusion, on the other hand, increases revenue. Its energy comes from matter itself, making it equivalent to humanity creating an artificial mini-sun."
"Once controlled nuclear fusion matures, no other energy source will matter. With an endless supply of ultra-cheap energy, human society will undergo unprecedented changes."
"Of course, increasing revenue is far too difficult, so no one can say when we'll manage it." Song He shrugged. "The various forms of energy we're tinkering with now are actually still confined to the realm of reducing expenditure."
"Photovoltaic power generation means making highly efficient, direct use of solar energy?" Lu Geng understood. "Other energy sources suffer losses from too many intermediate steps, while photovoltaic power generation directly turns sunlight into electricity, so its conversion rate is somewhat higher?"
"Somewhat?" Song He smiled. "It's not merely somewhat higher."
"Shockingly higher." Xiang Xiaotong nodded as well.
"Just make a comparison and you'll know. Take the most common crops. Guess what their light-use efficiency is?" Song He asked.
"I think I saw it somewhere..." Yu Banmeng desperately searched her memory. "Ten percent?"
"The theoretical maximum light-use efficiency is 10%, but the actual figure is far lower. Take rice, the most important food crop: it only reaches 0.3% to 2%." Song He said, "Other