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Lecture 34

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

2 pages50 viewsFall 2017

Department
Earth And Planetary Science
Course Code
EPS 7
Professor
David Romps
Lecture
34

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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 $
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