Unit 6.8 - Solar Energy

Question 1

Active vs Passive Solar Energy

Answer 1

• Passive Solar: absorbing or blocking heat from he sun, without use of mechanical/electrical equiptment
• Active solar - use of mechanical/electrical equiptment to caputre suns heat (solar water heaters or CST - consentrated solar thermal), or convert light rays directly into electricity (PV cells)

Question 2

Passi ve solar

Answer 2

• absorbing or blocking heat form the sun without using mechanical/electrical equiptment
• using the suns heat to cook food in a solar over
• Orienting building deisgn to bloc sunligt in warmer months abd allow sunlight in during cooler months
  - double paned windows, southern facing windows 2/ roof overhanging, decidious shade trees, skylight to decrease electricity use, dark colored sunlight absorbs floor

Question 3

Active Solar

Answer 3

• Use of mechanical/electrical equiptment to capture suns hear (solar heaters of CST - concentrated solar thermal) or convert light rays directly into electricity (PV cells)
• solar water heaters capture suns heat in water or circulating fluid and transfer heat to warm water for home - in place of electric/gas water heater

Question 4

Photovoltic Cells (PV)

Answer 4

• Aka “solar panels”; contain semiconductor (usually cilicon) that emits low voltage electrical current when exposed to sun
• Photons (particles carrying energy from sun) cause seperation of charges between two semiconductor layers (neuton and proton); electrons seprarate from protons and flor through circuit to load, delivering energy (as electriity)
• PV cells on a roof can directly powe the building, or send excess electricity back to the grid for other users (earning you a credit from your utlity company)
• A drawback is intermittency - solar energy can only be generated during the day
  - could be solved by cheaper, larger batteries tht can store energy generated during the day for use as night
  - currently these aren’t cost-effective yet

Question 5

Concentrated Solar Thermal (CST)

Answer 5

• Heliostats (mirrors) reflet suns rays onto a central water tower in order to heat water to produce steam to turn a turbine -> electricity
• A drawback is habitat deconstruction and light beams frying birds in mid air

Question 6

Community (solar farm) vs rooftop solar

Answer 6

• Large-scale solar “farms” can generate lots of electricity, but do take up land and cause habitat loss/fragmentation
• rooftop solar doesnt take up land, but only produces a little electricity

Question 7

SOlar Energy pros

Answer 7

• No air pollutants (PM, SOx, NOx) released to generate electricity
• No CO2 released wehn generating electricity
• no mining for fossil fuels for electricity production
• renewable, unlike Fossil Fuels which will run out

Question 8

Solar Energy Cons

Answer 8

• Semiconductor metals (silicon) still need to be mined to produce PV cells
• This can disrupt habitats and pollute water with mine tailings, ar with PM
• Silicon is a limited resource
• Solar panel farmscan displace habitats