# EPS 7 Lecture Notes - Lecture 34: Wind Turbine, Net Metering, Capacity Factor

2 pages50 viewsFall 2017

Department

Earth And Planetary ScienceCourse Code

EPS 7Professor

David RompsLecture

34This

**preview**shows half of the first page. to view the full**2 pages of the document.**Lecture 34

Domestic policy: CPP, ITC, PTC, alphabet soup

Promoting switch to renewables

1) ITC

- The investment tax credit pays for 30% of the cost of installing solar PV on

your roof

- My house uses 350 W of electricity, 400 W isn’t enough (it is rated power)

- Rated power is the out put under idea conditions, e.g., facing 1000 W/m2 of

incoming sunlight

- The capacity factor is the ratio of actual power output to rated power output

- Actual power = capacity factor x rated power

- For solar in California, the capacity factor is roughly 0.15

- Since I need 350 W, the equation above becomes: 350 W = 0.15 x rated power

- Rated power = (350 W)/ 0.15 = 2300 W, the panel is about 250 W, so I need

(2300 W) / (250 W/ panel) = 9 panels

- What about nighttime?

2) PTC

- The production tax credit (PTC) provides 2 cents/kWh of electricity

generated by a wind turbine in the 10 years since its installation

- What the heck is kWh? It is a stupid unit, there are lots of stupid unit

- One smart unit: Joule

- 2 cents / kWh = 20 dollars / MWh = 20 dollars / (1 million W x 3600 s)

- = 20 dollars / (3.6 billion W x s) = 20 dollars / (3.6 billion J) = 20 dollars /

(3.6 GJ) = 20 dollars / (4GJ) = 5 dollars / GJ (is this a lot of a little?)

- The PTC pays 5$ /GJ for the first 10 years

- How many GJ do wind turbines generate in 10 years?

- Let us imagine that we install 1 W of wind turbines

- The cost of utility scale wind is 1$/ W, so that 1W of rated power costs us 1$

- For wind, the capacity factor = 0.3

- So, 1 W of rated power produces roughly 0.3 W of electricity

- How much energy does this 0.3 W amount to be in 10 years

- 0.3 watt x 10 years = 0.3 watt x 10 years x (30,000,000 s/ year)

- = 0.3 watt x 300,000,000 s = 90 MJ = 100 MJ = 0.1 GJ

- We pay 1$ to install 1 W of rated power wind turbine, and that generates 0.1

GJ of electricity each decade

- The PTC pays: 0.1 GJ x (5$/GJ) = 0.5 $

- The PTC effectively pays for roughly 50% of the installation

3) RPS

- Renewables portfolio standard: a requirement on retail electric suppliers

- To supply a minimum percentage or amount of their retail load with eligible

sources of renewable energy

4) Net metering

- Net metering is a policy, which caries from state to state, that allows

residential customers to pay only for the net amount of electricity they use

- I need 2.3 kW of rated power. How much would it cost to go solar, taking

advantage of the ITC and net metering?

- Cost of installing residential solar is roughly 3$/ W

- (2.3 kW) x ( 3$/ W) x (1-0.3) ITC

- = 6.9 k$ x 0.7

- = 7000$ x 0.7 = 5000 $

###### You're Reading a Preview

Unlock to view full version

#### Loved by over 2.2 million students

Over 90% improved by at least one letter grade.