Renewables: The Elements Move
2018; Elsevier BV; Linguagem: Inglês
10.5040/9781350054011.ch-008
ISSN1873-7153
ResumoTh e fundamental source of earth's energy, our sun, has infused biomass energy into the planet since the fi rst chlorophyll cells evolved in cyanobacteria a few billion years ago.Th is evolutionary innovation fabricates chemical energy, sugars, from the energy in photons.As we have seen, almost all the food and fuel we have ever used has come as a consequence of solar rays driving photosynthesis.Geothermal energy is the rare exception.We usually gobble solar energy through plant vectors, both recently alive as biomass and long dead as fossil fuels.But this googolplex of solar voltage has only been captured directly to perform work for a few decades, since the fi rst solar panels were launched into space to power satellites in the late 1950s.Viewed from the economics of fuel, the sun is an energy paradox: a hemisphere of energy constantly hits the earth, but it is dispersed and sporadic in many cloudy regions, so the energetic infi nity of solar infusion dwindles down to a scattering of solar panels powering a small fraction of our machines.Th e discrepancy is less evident with wind and water, the elemental engines put in motion by the sun.Since antiquity, humans have built mills to yoke the power in their motion.Watermills were especially important prime movers in preindustrial civilization, where a constant supply of energy was required to grind and press and saw the raw harvests into consumable goods like fl our, oil, and lumber.Th e manufacturing centers of early modern Europe tapped into primary energy by clustering around regions of moving water, which must be counted among the essential natural resources of the continent (Cipolla 93).Th e limiting factor on the expansion of preindustrial European economies was a severe lack of energy, seen especially in the overconsumption of biomass like timber and charcoal.Medieval and early modern Europeans built mills wherever coursing water allowed, thus supplementing the restrictive energy economy, as the river performed the work that other societies extracted from slave labor and
Referência(s)