RENEWABLE ENERGY
Wind
Solar Photovoltaics (PV)
Hydroelectric Power
How Does It Work?
Turbines + Farmland =
Producing all US electricity with Wind...
Block Island 30MW Wind Farm (RI)
As of December 12, 2016, the nation's first offshore wind farm was operational!
How many turbines would we need? How much land?
What Information Do We Need?
Construction of Vineyard Wind began in 2019: 800MW array using 84 9.5MW (HUGE) turbines.(about 30 miles south of Martha's Vineyard)
- Capacity factor of wind is 20-50% -- 40% is a good assumption.
- On average, land use is about 0.135 square miles per MW (installed capacity)
- Power ratings of turbines mostly range from 1MW to 10MW, with most current installations at about 2.5MW
Vertical Axis Wind Turbines
Cost & Generation Capacity
https://www.eia.gov/renewable/
Iowa: 56,270 sq miles & Texas: 268,800 sq miles
Wind generation share exceeds 10% in 11 States in 2015
LCOE of Gas Turbine Combined Cycles is around $45/MWh (EIA)
"Federal leasing for offshore wind grows as first U.S. offshore wind farm comes online" - EIA
PTC = Production Tax Credit
https://windexchange.energy.gov/maps-data/321
How Do
How It Works
Photovoltaic
Systems Work?
How much land would we need
Types
to produce all US electricity with solar?
Amorphous Silicone
(Thin Fiml)
Monocrystalline Silicone
Polycrystalline Silicone
Types of Hydropower
P-N Junction
What do we need to know for this calculation?
- Two types of silicon have a positive--P-type--and a negative--N-type-- charge (due to extra electrons or missing electrons).
- When sunlight hits the solar cell, it adds energy to the electrons, causing them to move from one side to the other, through a circuit.
- Electrons moving through a circuit is what current, and electricity, is.
BIG
SMALL
Decreasing Cost
Increasing Efficiency
Total Annual US electricity consumption is 15.03 Quad = 15.8 EJ = 15.8E12 MJ
= 4.39 E12 kWh
Less than 10 MW (maybe less than 30 MW)
The bottom line is cost per installed watt
US TOP FIVE:
1. Grand Coulee: 6,809 MW
2. Bath County PSP: 3,003 MW
3. Niagara Falls: 2525 MW
4. John Jay Dam: 2,160 MW
5. Hoover Dam: 2080 MW
Panel efficiency is 8-20% (good estimate: 15%)
Solar Costs
are
Falling
(United States)
LCOE of Gas Turbine Combined Cycles is around $45/MWh (EIA)
Size of Arizona: 114,000 square miles
Environmental Consequences
- Often use existing dams
- Don't generally change the river bed or flow rate much
- Many fewer environmental impacts from dams
- Mostly for small communities, industry buildings
54% of new additions in 2017 were in China. 10.8% in US (@ #2).
Biggest Dam in the World:
Three Gorges Dam, 22,500 MW
Mostly tapped out in the US
How much of the US has a resources suitable for generating electricity with PV?
http://www.switchenergyproject.com/topics/hydro#/koonin-energy-expert-on-hydroelectric
- Major land use changes (loss of forests and other natural ecosystems, wildlife impacts, displaced communities of people)
Three Gorges Dam in China, before and after
Total
- Changes to river ecosystem: stagnant water changes nutrients, leads to more algae, less O2, less fish, more CO2 as algae decomposes. Water can evaporate from reservoir and downstream may dry up in drought.
Installed
Capacity:
46 GW
Germany: 35.5 GW
Spain: 5.6 GW
US: 12 GW
7 GW
http://calculators.energy.utexas.edu/lcoe_map/#/county/tech
Costs of Solar Photovoltaics
51 GW
How expensive is it, really?
- Lifecycle GHG emissions for building and operating the plant are generally about 0.06 pounds of CO2 per kWh fro big plants (0.01 to 0.03 lbs CO2/kWh for small), except for dams in tropical areas or temperate peatlands, then it can be significantly higher.
(2010)
These numbers are from EIA for 2018. Solar Energy Industries Association says total US installed capacity reached 71.3GW in 2019
“By the end of 2020, solar PV is expected to be cost-competitive with retail electricity prices, without subsidies, in a significant portion of the world,”
-Dexter Gauntlett of Navigant Research.
Flowind, Altamont Pass, California, USA (photo from US DOE)
Hoover Dam on the Colorado River, Arizona/Nevada Border
How Does It Work?
Combustion * Gasification * Waste Methane Gas
Strengths and Weaknesses?
- Still produces CO2
- Dirty: pollution is comparable to coal
- Some waste stream management issues & challenges
- Siting and NIMBY
- Carbon cycle for biomass is much shorter (so can be considered renewable)
- Consumes waste that might otherwise be in a landfill (solid waste is a pollution in its own right)
- Waste can be gasified and used in a IGCC plant (just like coal)
- Methane produced in landfills and from manure pits can be used to produce electricity, too
Concentrating Solar Power (CSP)
Geothermal Electricity
Biomass (or Waste)
Types
Concentration Ratio, Temperature, and Efficiency
Efficiency here is the product of the Carnot Efficiency and a receiver efficiency that includes radiative losses (absorbed radiation minus re-radiated energy divided by total solar radiation)
SWITCH VIDEO
http://www.switchenergyproject.com/topics/geothermal#/energy-overview-geothermal
Krafla Geothermal Station in northeast Iceland
Ivanpah Solar in Mohave Desert, California (Rendering by Abengoa Solar, currently under construction)
Discussion Questions
Is it possible to fully sustain economic growth while
at the same time taking better care of the environment? Will renewable energy sources be enough to both keep GHG emissions low but also continue to grow our worlds economy? (Bora)
DISCUSSION
- Take a few minutes, individually, to think about the reading. What stood out, what surprised you, what do you have questions about. Generate questions for the class to discuss.
- The authors discuss the cost of a transition to a low GHG economy on page 24.
- Is this a lot, or not really? What kind of information would help you contextualize it?
- Should we make that commitment? How much of that cost should the US take on?
- Section 7 (pp.24-26) discusses policy. Why is policy important? In what ways can it help? What types of policy could be useful?
- If you were a policymaker, what would you take away from this report? What would you do?
"A transition to a low-GHG economy with higher shares of RE ould imply increasing investments in technologies and infrastructure. [They]... estimate global cumulative RE investments (in the power generation sector only) ranging from USD2005 1,360 to 5,100 billion for the decade 2011 to 2020, and USD2005 1,490 to 7,180 billion for the decade 2021 to 2030.” The higher value reflects a path to stabilize CO2 concentrations at 450ppm. “The annual averages of these investment needs are all smaller than 1% of the words GDP.”
The middle ground approach suggests that new designs for electricity systems should maximize environmental, economic and security goals. Considering the stance that the past few years have not prioritized the environmental aspect, is it fair to request that companies, or even the government, take a financial loss in the modern day to account for the environmental loss? (Dani)
Intergovernmental Panel on Climate Change (IPCC)
The IPCC report states that renewables have the capacity to meet global electricity demands. Can renewables be the main (or only) source of energy in the near future without major breakthroughs in power storage and transmission? Will they be a good enough baseline energy source? (Jeff)
The chapter argues one way to combat a NIMBY mentality is when people become more acquainted with the associated benefits of the new technology (automobile/horse-drawn carriage example). How should proponents of renewable energies get opponents more acquainted with the benefits to minimize their reluctance to invest in these technologies? (Scott)
Special Report on Renewable Energy Sources and Climate Change Mitigation (SSREN)
Where is policy effort best spent? Incentivizing renewable energy and fighting the fossil fuels industries to remove subsidy, or funding R&D of renewable energy to lower the costs? (Evan)
What governmental or societal changes can we make, besides simply throwing more money at renewables, to bridge the current gap in price between fossil fuels and renewables? (Zach)