United States

United States

Windeconomics: New studies show why size matters

UNITED STATES: Three reports from America, covering onshore, offshore and the distributed market for smaller wind-turbine installations, confirm that wind energy continues to develop strongly, and with falling costs.

The US added 8,203MW of new capacity in 2016, bringing the cumulative total to more than 82GW. Turbine sizes and ratings continued to increase, while costs continued to fall.

Machines installed in 2016 had an average power rating of 2.15MW, and average rotor diameter of 108 metres (see chart, below).

The ratio of the power rating to the swept area — the specific rating — continued to decrease, bringing the 2016 figure to 234 Watt per square metre (W/m2).

The steady fall in the specific rating masks the magnitude of the fall in hardware costs. In 2010, the average installed cost was $2,361/kW, compared with $1,587/kW in 2016 (see chart, below).

But in 2010 a kilowatt came with 311m2 of rotor area, giving an average installed cost of $7.59/m2.

In 2016, the rotor area for a kilowatt had gone up to 429m2, making the average installed cost $3.7/m2. Costs for the hardware, therefore, more than halved in 2010-2016.

Sizes and ratings are steadily growing, but the decline in costs may be slowing, although it is too early to be definite. Prices for recently ordered wind turbines are in the $800-1,100/kW range.

This suggests balance-of-plant costs are around $500/kW. Ten years ago, these costs were about the same in dollars /kW terms, but looking at dollars /m2, there has been a significant decline.

Economies of scale have a big influence on installed costs. Average costs for projects of 20MW or less are around $3,000/kW, while those of 200MW and above were around half of this.

Operation and maintenance costs are also on a downward trend — from about $50/kW/yr at the turn of the century to around $30/kW/yr in 2015, but there is a lot of scatter in the data, and it is not always clear exactly what is included.

Distributed wind

Distributed wind is defined by a project's location relative to end use and power-distribution infrastructure. It includes systems at homes, farms, businesses, public and industrial sites that offset all or a portion of the local energy consumption at or near the location.

There is no specific size limit, but most are below 100kW, with many in the 2.5-10kW range or smaller. The total capacity installed in 2016 was 2.4MW.

Costs are falling here too, but small wind-turbine systems are more expensive than megawatt-scale installations.

Installed costs vary widely; from around $5,500-10,500/kW at the 10kW scale to around $4,800/kW in the 100kW category.

Offshore wind

The US only has one offshore project — the 30MW Block Island commissioned in late 2016 — so this report discusses global developments and the US pipeline.

Total capacity installed globally in 2016 was 1,188MW, and around 4GW is expected to be commissioned in 2017.

The global offshore pipeline is estimated to be around 231GW, of which 2.9GW is for floating turbines. The US pipeline is estimated as 24.1GW.


Wind Technologies Market Report 2016, Wiser, R and Bolinger, M, Lawrence Berkeley National Laboratory, August 2017 Looking at declining specific power rating shows true fall in installation costs.

2016 Offshore Wind Technologies Market Report, Musial, W et al, National Renewable Energy Laboratory, August 2017 Developments in offshore wind, worldwide, and US progress.

2016 Distributed Wind Market Report, Orrell, A et al, Pacific Northwest National Laboratory, August 2017 Costs are falling too but small systems are more expensive than MW-scale projects.

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