The longstanding relationship between physics and engineering is that physicists discover new phenomena and engineers figure out how to harness these discoveries for purposes useful to civilization. Physics leads and engineering follows. So, I was surprised to see an article in the March edition of Physics Today, the flagship publication of The American Institute of Physics (AIP), concerning solar energy conversion, a topic that long ago passed into the providence of engineering. That solar energy has caught the eye of physicists (who would otherwise be debating the size of the universe) highlights the prominence renewable energy has attained within all branches of science and engineering.
Physics Today is notorious for its slothful writing, which is often so encumbered with jargon and technical language that Nobel prize winners cannot follow the articles. This magazine usually contains narrative that only a mother (or a physicist) could love. Nonetheless, George Crabtree and Nathan Lewis have bucked the trend, publishing a well-written article entitled, “Solar energy conversion”, fit for us, the "unedumicated" masses.
The beauty of the Crabtree-Lewis article is its succinct description of solar energy’s three sub-categories: photo-electric, bio-fuel, and heating. Each sub-area is coved in terms simple enough for non-physicists to follow while providing adequate detail on new advances to prevent the article from seeming pedestrian to those fluent in solar power. In addition, the authors expertly frame the potential of solar in terms of a few critical numbers. Civilization utilizes 13 terawatts. The sun bathes the Earth in 120,000 terawatts; that’s 4.6 x 1020 joules in one hour. The estimated energy contained in all the world’s fossil fuel reserves is 1.7 x 1022 joules. So, the Earth receives energy from the sun equal to all our fossil fuel reserves every 1.5 days. If we could capture a minute fraction of that energy, not a single drop of oil would ever need to be burned again.
Unfortunately, energy storage, which is arguably solar energy’s most serious unresolved challenge, is barely grazed by this article. Nonetheless, I would recommend “Solar energy conversion” as a quick read for any aspiring energy buff who wants to get up to speed on the state of the art in solar energy conversion.