Material requirements of 50% wind power in the USA hit limits to growth
Davidsson, S., et al. 2014. Growth curves and sustained commissioning modelling of renewable energy Investigating resource constraints for wind energy. Energy Policy.
Fizaine, F., et al. July 2014. Energy transition toward renewables and metal depletion: an approach through the EROI concept. Les Cahiers de la Chaire Economie du Climat.
Wind turbines can’t be made forever because lower grade ores require more and more energy at a time when energy resources are declining. The natural gas, coal, oil, uranium (thorium), neodymium, and other energy resources and minerals needed for wind turbines are finite. It takes energy to recycle, and few metals are cycled as much as they ought to be, and some can’t be recycled.
Since wind and solar need to provide the lion’s share of renewable energy in the future, but wind only blows 32 percent of the time nationally, you’d want to build at least three times as many wind turbines to store energy while the wind is blowing for calmer times. Or perhaps even five times overcapacity to cope with the seasonal nature of wind, which is only at 21 percent capacity in August. Plus you’ll need to generate more electricity than in 2014 for the billion people expected by the end of the century, so perhaps six times more. Or let’s go for seven times more, since endless growth is the solution offered by both political parties as the way out of our economic doldrums, especially “green” growth.
Tripling the number of wind turbines to compensate for the 32% capacity gets you:
5,606 MWh power/year per turbine = 2 MW * .32 capacity * 24 hrs * 365 days
730,099 windmills = 4,092,935,000 MWh /5606 MWh (EIA 2015 1.1) = needed. Cross-check: NREL estimates that 893,698 1.5 MW turbines are needed for 80% wind penetration by 2020 in class 4 wind, 2 x 40% case = 3914 TWh (NREL 2006)
$2.2 to $2.9 trillion dollars (@ $3 to $4 million per windmill)
This won’t provide 100% of America’s energy because the round-trip efficiency of most energy storage is 80%, wind capacity is 25 percent in summer, wind turbine performance declines over time, non-prime locations will lower the average wind capacity, two to nine percent of electricity is lost over transmission lines, and their lifespan is 20 years, so increasing numbers will need to be replaced or out of commission from repairs.
Area required is 193,933 square miles = (85 acres/MW (NREL 2009) * 2 MW turbines * 730,099). That’s about 72 percent of Texas, or California plus South Carolina, or .66% of the total lower 48 states, but doesn’t include the roads, transmission line and tower corridors, and other equipment.
|Material||Short Tons||Tons for 730,099 2 MW turbines||Production in short tons per year|
|Concrete||1302.35||950,844,433||142,464,000 United States (USGS)|
|Steel||292.75||213,736,482||1,800,064,000 world-wide (worldsteel)|
|Fiberglass||24.4||17,814,416||1,523,200 (USA 2005 production)|
|Neodymium||0.4||292,400||7,840 world-wide (ED)|
|Dysprosium||0.065||44,456||112 world-wide (ED)|
Materials per 2 MW turbine (average of Guezuraga, USGS). Fiberglass annual production (NREL 2006).
Clearly materials can be imported, more manufacturing built up – but as energy declines and the financial system copes with shrinkage, the opposite of the current borrowing and paying back the money from growth, it’s not clear that ramping up is likely — quite the opposite is possible, with many businesses going bankrupt.
Fiberglass would require 100% of production for 11.7 years.
Materials not included: vehicles, cranes to hoist blades and tower, thousands of miles of transmission lines & towers, substations, utility-scale energy storage, etc.
EIA. 2015. Table 1.1. Net Generation by Energy Source: Total All Sectors, 2004-December 2014. Energy Information Administration.
EIA. 2015. Table 6.7.B. Capacity Factors for Utility Scale Generators Not Primarily Using Fossil Fuels, January 2008-November 2014. U.S. Energy Information Administration.
Guezuraga, B. 2012. Life cycle assessment of two different 2 MW class wind turbines. Renewable Energy 37:37-44.
NREL. 2006. High Wind Penetration Impact on U.S. Wind Manufacturing Capacity and Critical Resources. National Renewable Energy Laboratory.
Prieto, P. A. 21 Oct 2008. Solar + Wind in Spain/ World. Closing the growing gap? ASPO International conference.
USGS. 2011. Cement production. United States Geological Society. 127,200,000 long tons converted to 142,464,000 short tons (2,000 lbs)
USGS. 2011. Wind Energy in the United States and Materials Required for the Land-Based Wind Turbine Industry From 2010 Through 2030. U.S. Geological Survey.