Wind Energy – worth the breeze?

Wind needs the sun

Sun is playing a significant part in the formation of winds and wind energy.

The suns thermal energy heats earth’ surfaces.

The difference in surface temperatures is causing the emergence of wind. Hence, as long as there is the sun, there will be wind.

Early starts of harnessing the wind

The first-ever wind turbine, to generate electricity, was installed in 1888, in Cleveland, Ohio.

It was designed to run at a peak capacity of 12 kilowatts (kWp). This marked the beginning of electricity generation from winds.

How wind turbines work

Windmills and turbines take advantage of the kinetic energy that comes along with moving air.

The air is then convicted to electricity via the rotors and generators.

Efficiency vs capacity factor

Before going into greater detail of how efficient this process is, we need to distinguish between two significant terms:

  • wind turbine efficiency

  • capacity factor 

Windmill in a field

Wind turbine efficiency is the amount of kinetic energy converted into electricity.

In contrast, wind capacity factor is the average power produced, in relation to what it could generate if always running at full capacity.

E.g. a three-megawatt wind turbine produces an average power of one and a half megawatts; then its capacity factor is 50% (1.5/3 = 0.5, i.e. 50%).

This factor varies from place to place, and even from year to year. 

Advantages and disadvantages of wind energy 

In the following, we will show some advantages and disadvantages of wind power in comparision to other energy sources.

Theoretical limitations

Due to laws of physics, theoretical wind efficiency is limited to 59.6%.

This is the maximum capability to which kinetic energy can be trapped inside wind turbines.

Due to further limits caused by the way generators and turbines are engineered, an average of 35-45% of the winds “moving energy” is trapped. 

Wind vs other energy sources

Let’s have a look at how efficient wind is compared to other utility energy sources.

Coals energy efficiency only lies around 29-37%, underperforming winds energy efficiency.

Gas is competing for heads on with between 32-50% of its total energy being transformed into electricity.

Nuclear power, has a high capacity factor of 92.5%. However, the efficiency factor is limited at 30%.

Other renewable energy sources, such as hydro power, claim higher efficiency factors than wind farms.

Solar PV lags a bit behind with only ~26%.  

Modern wind farm on a beach

Intermittency of wind power

Another factor that needs to be considered is the intermittency of winds resulting in uneven generation of power.

Due to the lack of an constant energy flow, wind is often critizised for being an unsecure power source.

Therefore, the grid has to balance energy supply obtained from wind turbines continually.

With technological advancement and new projects for building additional wind farms, this intermittency is more comfortable to handle. 

Especially, once storage solutions will be an integral part of wind farms.

Each wind park will then be amended with huge energy storage solutions.

Biggest advantages of wind power

So, what is it that makes wind farms and energy generated from wind attractive?

Two factors, costs & it’s carbon-free generation.

Costs of on-shore wind turbines

In 2017, the average costs to generate an MWh were highly depending on the specific country’s regulations and natural circumstances.

For onshore windfarms Mexico and Canada showed record-breaking bids of EUR 14.20 and EUR 23.00 respectively.

These per-MWp-costs are touching ground within worldwide market prices.

Germany in comparison had their lowest onshore bid at EUR 38.00, and an average of EUR 47.30.

France awarded bids averaging at EUR 65.00, dropping 21% from the year before.

Costs of off-shore wind turbines

In Germany, offshore bids, auctioned at EUR 46.60 per MWh, which is genuinely higher than onshore bids.

This is due to lower levelized costs of electricity (LCOE) for onshore windfarms, as of significantly lower EPC- and O&M-costs.

Technological outlook for wind energy

With evolving technology and the expansion of total capacity of wind farms, especially offshore, overheads will decline further.

With only 20% of the total expenditures going into operational costs, wind turbines are set to be competitive, over the course of their lifetime. 

The remaining 80% are initial CAPEX (Capital Expenditures) and will decline due to economies of scale. 

Diameters of a wind turbine

Speaking of progress in the wind energy sector, turbine towers and their rotors reach impressive heights and diameters.

Standing at 260m, a rotor of 220m and blades of 107m tall, wind turbines unleash a maximum capacity of 12 MWp.

This record-breaking turbine generates a total of 67 GWh gross p.a.

16,000 households will be powered with this turbine.

Wind power in the global energy mix

Generally, wind energy contributes up to 5.5% of the global electricity demand. 

Update:

Siemens recently announced another increase in capacity factor. They have introduced the 15 MWp Simens Gamesa 15-222 DD model. 

What other aspects would YOU like us to look at more deeply for the next time?

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