6.8 solar energy

passive solar

absorbing or blocking heat from sun, without use of mechanical/ electrical equipment

active solar

use of mechanical/electrical equipment to capture sun’s heat (solar water heaters or CST (concentrated solar thermal), or convert light rays directly into electricity (PV cells)

photovoltaic cells (PV) aka “solar panels”

contain semiconductor (usually silicon) that emits low voltage electrical current when exposed to sun

intermittency

solar energy can only be generated during the day

concentrated solar thermal (CST)

heliostats (mirrors) reflect sun’s rays onto a central water tower in order to heat water to produce steam to turn a turbine > electricity

drawback of CST

habitat destruction and light beams frying birds in mid air

community (solar farm)

large scale solar “farms” can generate lots of electricity, but do take up land and cause habitat loss/fragmentation

rooftop solar

doesn’t take up land, but only produces a little electricity

solar energy pros

no air pollutants (PM, SOx, NOx) released to generate electricity; no CO2 released when gen. electricity, no mining of fossil fuels for electricity production, renewable unlike FFs which will run out

solar energy cons

semiconductor metals (silicon) still need to be mined to produce PV cells (solar panels); can disrupt habitats and pollute mine tailings, air with PM; silicon is limited; solar panel farms can displace habitats