The generation of electricity from renewable energy sources such as wind, solar and geothermal has a copper usage intensity that is typically four to six times higher than it is for fossil fuels, according to a new market study titled, Current and Projected Wind and Solar Renewable Electric Generating Capacity and Resulting Copper Demand, conducted by BBF Associates and Konrad J.A. Kundig, Ph.D. and commissioned by the Copper Development Association (CDA).

"Copper Usage Intensity" is an estimate of the pounds of copper necessary to install one megawatt of new power generating capacity. Estimates of copper usage per megawatt are reported by the study as follows:

+ Approximately 21,000 pounds for offshore wind energy

+ 5,600 to 14,900 pounds for land-based wind energy

+ 5,400 to 15,400 pounds for photovoltaic (PV) solar installations

Copper Usage Greater Due to Size of Installations

"Copper usage intensity in onshore wind farms is strongly correlated to the physical size of the installation due to the miles of copper grounding cable and copper-concentric-neutral aluminum-conductor power cable installed over large distances," says Zolaikha Strong, Director of Sustainable Energy for CDA.

Other important contributors to copper intensity include magnet wire for generators and transformers, DLO cables, control and communication cables, and bus bar for switchgear.

Offshore Wind Farms Offer Growing Opportunity
Although no offshore wind farms currently exist in the USA, the potential is great and plans are in place for Massachusetts, Maine, New Jersey and Ohio. Estimates of copper usage intensity for offshore wind are based on experiences in the United Kingdom.

Offshore wind energy represents a huge opportunity for copper because submarine collector and transmission cables are normally 100-percent copper, due to the fact that copper does not promote the growth of corrosive barnacles because of its natural anti-fouling properties.

The study points out that "According to the EIA's Annual Energy Outlook 2011, growth of the U.S. renewable energy (RE) industry is currently driven by Federal tax incentives and state renewable energy portfolios. In place in 29 states, the portfolios mandate the minimum renewable energy fraction of total capacity.

Additional drivers, not cited by the EIA, include the perception that RE reduces dependence on imported fuels and the fact that it improves atmospheric quality. EIA estimates that RE will dominate new electric generation build-outs until 2016-2020."

Photovoltaic (PV) copper usage is linearly scalable because the copper between individual solar panels is relatively constant. Parabolic-mirror, thermal solar uses less copper since it is a nonelectrical, fluid-based system; but motor-driven tracking devices could use 8,800 pounds of copper per megawatt.

Tower-type thermal solar power plants (which use mirrors to direct concentrated sunlight onto an elevated boiler) require robust grounding for lightning protection and mirror tracking systems. For geothermal, which is similar to hydroelectric in that it is limited to suitable geologic sites, copper is used in traditional turbine-generators, step-up transformers and the grounding system, just as in fossil-fired plants.

"Copper usage intensity for renewables is high because solar panels and wind turbines are spread over large land areas," added Strong. "Once installed, of course, copper is not consumed like a fuel but rather performs its functions for many years and ultimately is recyclable."

According to Strong, copper is an "enabling element" because it allows for the collection of electrical energy from broadly dispersed energy sources while minimizing electrical losses.

"The usage of copper in renewable energy is an investment in a sustainable infrastructure and a sustainable future. Copper is one of greenest metals on the planet when it is used in this manner," she said.