Thursday, October 25, 2012

Copper Use in Energy Generation

Some assorted quotes:

According to Professor Ronnie Belmans, President of the International Electricity Union, “the judicious use of 1 tonne of copper in the energy sector makes it possible to reduce CO2 emissions by 200 tonnes per year on average” (source).
Premium efficiency electric motors (at the 10 horsepower level) contain nearly 10 kilograms of copper, which is roughly 75% more copper than a standard efficiency electric motor (data is per the International Copper Association) (source). 
Conventional automobiles contain 8kg to 33kg of copper, with the electrical distribution system/wiring harness accounting for about half of the copper used.  Hybrid electric cars contain an estimated incremental 33 kg of copper (source).
New high-speed trains with their electric traction engines use from 3 tons to 4 tons of copper, which can be more than double the copper content of traditional electric trains (source: International Copper Study Group).  Additionally, the overhead cables that supply the power to high-speed trains are made of pure copper or a copper alloy. One kilometer of cable uses 10 tons of copper (source)!
Renewable Energy (Solar and Wind)
Electricity generation via wind farms and solar farms  require significantly more copper per megawatt of capacity than conventional electricity generation, with one industry source estimating that wind energy is twelve times as copper-intensive as conventional power generation.  Additionally, solar farms require 4 to 5 times more cable than wind farms of equal power generation (per the General Cable’s 2008 annual report) (Source).
Copper usage intensity, as measured in pounds needed per megawatt of new capacity (lb/MW) is larger in RE (Renewable Energy) plants of all sizes and types, by a factor ranging between two and almost six times, than that seen in conventional fossil- or nuclear-based generation. The multiplier is based on the assumption that conventional/nuclear plants utilize 2,000 to 3,000 lbs Cu/MW, and somewhat less in plants larger than one gigawatt in capacity. A study by the Shaw Consulting Group commissioned by CDA approximately 10 years ago cited significantly higher values for conventional plants, but CDA membership reviewers believed those figures to be excessive, a sentiment that the authors of this support (source).

Photovoltaic (PV) solar installations fall in the same usage intensity range as land-based wind, ranging from about 5,400 to 15,432 lbs/MW. An ECI study [Nuño, March 2011] reports reasonably similar values. Parabolic mirror-type thermal solar installations are less copper intensive than PV fields because these fluid-based systems are non-electrical and do not require grounding unless fitted with motor-driven tracking devices, in which case, according to the ECI study cited earlier, copper intensity will be 8,800 lbs Cu/MW (source).

The approximate intensity of copper use is calculated at 5.64 tonnes/MW of wind powered generating capacity installed onshore (based upon data from 30 planned or operating wind farms) and 9.58 tonnes/MW installed offshore (based upon data from 14 planned or operating wind farms). Analysis of standard decommissioning practice shows that previous estimations of copper availability for recycling may be over-estimated, with 31% of copper used onshore planned to be recycled and 18% offshore. The low copper recovery rates are primarily due to cable decommissioning practices that are justified on the basis of local environmental impact, standard industry practice and technical difficulties in offshore cable recovery (source).
Copper is a key material for generation of renewable energy - the generator in a 5MW wind turbine needs 3.4 tonnes of copper to convert the energy of the wind to electricity (source).
The land-based wind “farms” examined in the study require between 5,600 and 14,900 pounds of copper per megawatt (lb/MW).  Based on British experience, it appears that offshore wind farms may average as much as 21,076 lb/MW installed, including the submarine transmission cables to the onshore grid (source).
Copper is present in all the components of the wind turbine energy production chain, including there generator, the transformer, the rotor and the cables (a wind turbine of 1 MW requires 3.9 tonnes of copper according to the Leonardo ENERGY platform) (source).
Vestas V90-3.0 MW onshore wind turbine is selected as the subject of study because it is one of the mainstream large wind turbines with installations in various regions. The generator weight is given to be 8.5 tons. It is assumed to be composed of 35% copper and 65% steel. The gear system (called as well gearbox) has a total weight of 23 tons. It is assumed to be composed of 98% steel, 1% copper and 1% aluminum. The frame, machinery and shell unit has a given weight of 37 tons. It is assumed to be composed of 85% steel, 8% aluminum, 4% copper and 3% Glass Reinforced Plastic (source).
Infrastructure projects in emerging economies and demand from top global copper consumer China also will continue to fuel usage, according to Langner. A windmill contains about 8 metric tons of copper, with a further 5 to 8 tons needed for power connections, he said (source).
Current generation (a representative current-generation onshore wind turbine is capable of generating 1.5 MW of electricity using conventional technology that includes a three-blade rotor, steel tower, three-stage gearbox, and a wound-rotor type generator): 2'500 kg Cu per MW. Next generation (a representative next-generation wind turbine is capable of generating 3 MW of electricity and could use more composite materials in the rotor blades, steel-concrete towers, and a mixed generator technology assuming 80 percent double-fed induction generator technology and 20 percent permanent magnet technology. The latter could use rare-earth elements): 3'000 kg Cu per MW (source).
Summary of copper use (in tonnes of Cu per MW) estimates in onshore wind turbines:

0.68 (Copper Development Association) ??
2.54 (BBF Associates for Copper Development, low estimate)
2.50 (USGS current generation)
3.00 (USGS next generation)
3.90 (Leonardo Energy Platform for European Copper Institute)
4.69 (School of Architecture and Built Environment)
5.64 (University of Exeter onshore)
6.76 (BBF Associates for Copper Development, lhigh estimate)
9.58 (University of Exeter offshore)

The first data point is probably erroneous (3.40 tonnes Cu per 5 MW = 0.68 tonnes of Cu per MW), but it appears accordingly on the website of the Copper Development Association.

No comments:

Post a Comment