Good day, sunshine!

Please pass back the objective sheet.

Please read the board!

Why fossil fuels?

Why NOT Fossil Fuels?

What are the drawbacks of using fossil fuels?

“Alternative” energy sources are sustainable sources!

Solar Power

Photovoltaics Solar Thermal

Towers

Passive Solar Active Solar

Make Electricity

Make Heat

LET’S GO VISIT THE SPACE POD!

Notes today:

Write down all the new TERMS you see today.

Don’t worry about definitions or explanations.

We will process these tomorrow!

Photovoltaics

How does it work?

Photovoltaic cells contain a semiconductor material – creates a flow of electrons (electricity!) when hit by light.

Batteries store electricity for cloudy days or nights.

Discovery Green down town

Two arrays totaling 256 solar panels

Between 2007 and Fall 2014, the solar panels have generated over 117,000 kWh resulting in over $24,000 in energy savings. That is the equivalent of planting over 10,000 trees!

Ikea on I-10

3,388 panels Completed June

2012

Solar arc in Japan

5,000 solar panels

500,000kWh of electricity

Our electric “grid” = power plants connected to consumers

Photovoltaic Solar

Building connected to power plant and electric lines.

On cloudy days, at night, building gets electricity from the grid

Extra power can be sold back to the electric company!

Not connected to power plant

Requires batteries for night time

Can be far away from cities!

Grid connected Stand Alone

Solar panels are great for remote locations – “stand alone”

Customers don’t need to be connected to the grid

Must have batteries for back up.

Solar update!

US solar industry – record growth in 2012, 16,ooo,ooo panels installed in nation, record 76% growth

Texas is in the top 10 states for solar installation and has the “most untapped potential” for solar (still just .1%of electricity)

Module costs have dropped 60% last two years

Solar Leasing Program announced 2/10/15! (San Antonio)

CPS receives surplus kW to distribute on grid to other customers

Installation companies own and install solar panels on homes; rent the roof space from homeowners

Get electricity; surplus sold to CPS; rent check from installation companies

grid

CPS avoiding another centralized power plant! “CPS Energy is our utility, it’s owned by us, the

people of San Antonio. And the idea of our utility putting solar on our people’s rooftops, instead of building another centralized power plant – it’s a very exciting thing, and Solar San Antonio (SSA) is very supportive,” stated SSA Interim Executive Director Anita Ledbetter in a news release. Ledbetter is also executive director of Build Green San Antonio, the nonprofit sustainable building resource and third-party green building certification program.

Solar giants

Germany! - requires solar installation on new buildings; gave tax rebates for homes installing photovoltaics.

China – increased production of photovoltaic panels

Price has dropped by 60%

Advancements

Photovoltaic road panels!

Would keep road ice-free.

Light up when pressure is applied – safety at night!

OTHER KINDS OF SOLAR POWER

Solar towers! 2007 near Seville 624 mirror, 35-story tower Heat turns water to steam for turbines Power for 6,000 homes

How it works

Light bounces off mirrors and is concentrated at top of tower.

Molten salt is pumped to top of tower where light heats it up

Molten salt is used to turn water to steam turbine generator electricity!

Solar trough tech

Mirrors track sun’s movement

Passive solar – heats air or water; no electricity

• In winter when sun is low in sky, light enters, bounces, turns into heat which is trapped by the super-insulated windows and walls.

• In summer, wide roof overhang blocks sunlight, keeping house cool.

• Windows face south and west.

Hudson Passive Project NY

Villa Nyberg, Sweden

Passivhaus, Germany

Fablab house, Madrid Spain

Crossways, UK

Vogel House, Switzerland

Active systems

Active systems

• Water pipes on roof heat up.

• Water brought down into heat exchanger in house which warms the shower water.

• Cooled water pumped back to roof to warm up.

• Can also be used to heat a house with radiators.

Active systems

Water piping on roof warms water. (New Hampshire)

Active systems Can also be used to heat a house with radiators.

Water pipes on roof heat up.

Water brought down into heat exchanger in house which warms the shower water.

Cooled water pumped back to roof to warm up.

Active system

So what are the trade offs?

Benefits Disadvantages