Advances in technology play a key role in helping estimate long-term asset and site performance (Image courtesy of Shutterstock).

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Forecasting for success in onshore wind power


Patrick Sachon

In the first of a series of exclusive articles for Renewable Energy Focus, Patrick Sachon, Head of Renewables at the Met Office, explains the crucial role that forecasting plays in the onshore renewable wind energy market.

For the past five years, the Met Office has been investing to focus its services on supporting the wind industry as the renewable energy market grows. We’ve developed weather and climate services to meet the requirements of onshore wind, throughout all stages of the project lifecycle.

Currently, the wind industry in Europe is facing an ever-increasing number of challenges when it comes to developing energy profitably and at a cost which is competitive to other energy sectors. Downward trends in market support and incentive mechanisms have played a key part in this, and this is coupled with the rising cost of land acquisition, development and operations. The bottom line here is that margins have become even tighter and more difficult to manage.

Reduced support mechanisms

The reduced market support and incentive mechanisms offered by the UK Government to the renewables energy market may be seen by some as a bad thing. After all, it does make profits harder to come by and decreases the margin for error in site search, selection and development. However, my belief is that it is the correct decision. If renewable energy is to be a genuine alternative to other sources – and the latest Department of Energy and Climate Change (DECC) figures certainly substantiate its claim - the industry must become self-sufficient and stand on its own two feet.

The knock-on impact of this is a strong drive in the industry for cost reduction, increased efficiency and a reduction in the levelised cost of energy, which in the long term is important to help the sector become a viable and sustainable source of energy. Correct selection of sites is therefore vital, as failed onshore projects are completely counter to this. This focus on long-term profitability and sustainability is also demonstrative of a maturing industry which is streamlining its approach to become more efficient as it expands and increases its stakeholders.

Industry growth and changing public perceptions

The growth in the market is a very encouraging sign, with DECC’s July 2015 figures demonstrating that the renewables sector as a whole has increased by over a fifth (21 per cent) year-on-year, with the onshore wind generation sector increasing by a smaller, but still significant, ten per cent.

Public attitudes to onshore wind projects are also changing, which is important for the growth of the industry. Public opinion impacts government legislation, which in turn impacts expansion and the market environment. The latest figures from the DECC Public Attitudes Tracker show that 70 per cent of people now support the development of onshore wind – the highest figure since attitudes were first recorded in 2012. In addition, 80 per cent are concerned about the UK becoming reliant on energy imports. Onshore wind can play a vital role in helping to guard against this.

Long term performance

As a result of this squeeze in profits and with onshore wind growing and maturing as an energy sector, it’s become increasingly important to estimate long-term asset and site performance to establish the potential success for future projects. Stakeholders and investors need to be sure that a site can be profitable in order to inspire confidence in the project and to get it off the ground.

Advances in technology play a key role in helping estimate long-term asset and site performance. Earlier this year, the Met Office launched an updated version of its Virtual Met Mast™ product - a solution that accurately estimates long-term average wind speeds for potential new sites, as well as providing a reliable long-term reference for correlation.

We’ve touched on the importance of managing costs and the Virtual Met Mast can help achieve this, being considerably cheaper than installing physical meteorological masts. It allows those planning site locations to have the confidence in their selections and can also help their ability to gain investment in their projects.

The new version of Virtual Met Mast uses advanced downscaling processes in order to produce accurate, long-term site and hub height-specific wind climatologies, specifically for the European wind energy market. The data and resultant reports can then be used to support site search, selection and development activities across a range of wind energy projects.

One of the key innovations is the development of an ‘intelligence function’ that uses statistical techniques to build a knowledge base of correction factors between model, reanalysis and monitored data across a range of sites. It then applies these learnings in future to minimise resulting biases in wind speed results for new sites. This process is able to capture very detailed interactions between data, making it particularly effective in regions with complex terrain.

More than just site selection

The role that accurate meteorological forecasting plays in site selection is hopefully fairly self-explanatory – despite the science behind it being anything but! However, meteorology plays key roles in other aspects of planning and operations.

For example, as you would imagine, renewable wind projects are constructed in areas which experience high levels of wind. It is therefore important to have site-specific forecasts to aid safe and efficient planning of construction, operations and maintenance. For example, examining where weather windows of appropriate conditions will allow operations to take place safely for those involved. Not only does this offer important health and safety benefits, but it allows the most efficient planning for construction, operations and maintenance, ensuring time is optimally managed and used.

The Met Office’s VisualEyes™ product has been developed specifically for the wind energy industry and addresses this. The web-based monitoring and alert system helps manage conditions for onshore (and offshore) wind farms and informs management of maintenance schedules, operational risks and monitors weather conditions – for example, the risk of lightning or strong gusts. Used by many of the major utilities companies and the largest wind farm in Europe, it provides planning services for lightning, hub height wind and visibility for up to five days ahead.

In addition to the five-day planning charts it offers, customisable weather analysis reports can be generated up to 14 days in advance. These give detailed charts showing a selectable choice of weather elements. This includes surface wind speed, temperature, rainfall and snow. This detailed information ensures wind farm operators can safeguard staff and contractors, reduce maintenance costs, and by knowing the weather conditions forecast, mitigate against the stranding of staff or equipment.

In summary

It’s a very positive time for the onshore wind industry, with the key indicators of growth and public support continuing to move in the right direction. The converse, but necessary move to reduce the government support mechanisms demonstrates that the industry is moving in a more independent and sustainable direction. But there is less handholding, meaning that forecasting, science and technology will continue to play a very crucial role in helping the industry operate efficiently, profitably and with the foresight it requires. At the Met Office we look forward to maintaining our strong relationship with, and support for, the industry to ensure a greener and more sustainable future energy landscape.

ABOUT THE AUTHOR

Patrick Sachon is Head of Renewables at the Met Office.

 

 

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Comments

ANUMAKONDA JAGADEESH said

24 September 2015

Offshore wind power refers to the construction of wind farms
in bodies of water to generate electricity from wind. Better
wind speeds are available offshore compared to on land,
so offshore wind power’s contribution in terms of electricity
supplied is higher.
Power P = 0.5 p A V3 Watts.. .. (1)
Where P = Power,p density of air,V=speed of the wind and A
is the area of the intercepted airstream(equal to the ‘swept’
by the rotor).
In standard conditions(sea level, temperature 15 degrees
Celsius) the density of the air is 1.225 kg/m3. So the amount
of Power intercepted by each square rotor is:
P=0.612 V3 Watts …(2)
For Example,if the wind speed is 6 m/s(a moderate breeze)
the power intercepted per square meter is 0.612 X 63 =
132 W; but if the speed rises to 24 m/s(a severe gale) the
power becomes 0.612 X 243 = 8460 W. This massive
increase is due to cubic relationship between wind speed
and power by equation (2). Here the word’intercepted’ rather
than ‘captured’ is used because the above figures relate to
the power in the wind, not the amount actually extracted by
a turbine rotor. Large modern turbines typically capture up of
about 50% of the wind power presented to them.
Betz’s law is a theory about the maximum possible energy
to be derived from a wind turbine developed in 1919 by the
German physicist Albert Betz. According to Betz’s law, no
turbine can capture more than 59.3 percent of the kinetic
energy in wind. The ideal or maximum theoretical efficiency
n max (also called power coefficient) of a wind turbine is the
ratio of maximum power obtained from the wind to the total
power available in the wind. The factor 0.593 is known as
Betz’s coefficient. It is the maximum fraction of the power in
a wind stream that can be extracted.
Economics and benefits
Offshore wind power can help to reduce energy imports,
reduce air pollution and greenhouse gases (by displacing
fossil-fuel power generation), meet renewable electricity
standards, and create jobs and local business opportunities.
COST COMPARISON OF ONSHORE AND OFFSHORE
WIND FARMS
Onshore
Investment of about $1.5 million per MW
Levelized cost of 6-7 cents per kWh
O&M – 1-3% of capital costs
May be built in smaller units
Offshore
Investment of $2.3 million per MW
Levelized cost of about 10-11 cents per kWh
Higher O&M – 40$ per kW and 0.7 cents per kWh variable
Large turbines and farms required
In spite of the higher costs and the uncertainties involved in
offshore wind, research in this sector has been significant,
and the main reason is the potential offered by offshore wind
turbines, especially in lands close to water
Offshore wind power refers to the construction of wind farms
in bodies of water to generate electricity from wind. Better
wind speeds are available offshore compared to on land,
so offshore wind power’s contribution in terms of electricity
supplied is higher.
Power P = 0.5 p A V3 Watts.. .. (1)
Where P = Power,p density of air,V=speed of the wind and A
is the area of the intercepted airstream(equal to the ‘swept’
by the rotor).
In standard conditions(sea level, temperature 15 degrees
Celsius) the density of the air is 1.225 kg/m3. So the amount
of Power intercepted by each square rotor is:
P=0.612 V3 Watts …(2)
For Example,if the wind speed is 6 m/s(a moderate breeze)
the power intercepted per square meter is 0.612 X 63 =
132 W; but if the speed rises to 24 m/s(a severe gale) the
power becomes 0.612 X 243 = 8460 W. This massive
increase is due to cubic relationship between wind speed
and power by equation (2). Here the word’intercepted’ rather
than ‘captured’ is used because the above figures relate to
the power in the wind, not the amount actually extracted by
a turbine rotor. Large modern turbines typically capture up of
about 50% of the wind power presented to them.
Betz’s law is a theory about the maximum possible energy
to be derived from a wind turbine developed in 1919 by the
German physicist Albert Betz. According to Betz’s law, no
turbine can capture more than 59.3 percent of the kinetic
energy in wind. The ideal or maximum theoretical efficiency
n max (also called power coefficient) of a wind turbine is the
ratio of maximum power obtained from the wind to the total
power available in the wind. The factor 0.593 is known as
Betz’s coefficient. It is the maximum fraction of the power in
a wind stream that can be extracted.
Economics and benefits
Offshore wind power can help to reduce energy imports,
reduce air pollution and greenhouse gases (by displacing
fossil-fuel power generation), meet renewable electricity
standards, and create jobs and local business opportunities.
COST COMPARISON OF ONSHORE AND OFFSHORE
WIND FARMS
Onshore
Investment of about $1.5 million per MW
Levelized cost of 6-7 cents per kWh
O&M – 1-3% of capital costs
May be built in smaller units
Offshore
Investment of $2.3 million per MW
Levelized cost of about 10-11 cents per kWh
Higher O&M – 40$ per kW and 0.7 cents per kWh variable
Large turbines and farms required
As countries around the globe are realizing the potential of wind power, more and more turbines are being installed offshore. The world now has at least 5,415 MW of offshore wind energy generating around the globe.
Offshore wind presently represents about 2 percent of global installed energy capacity; but that number could, and is expected to, increase rapidly. Able to generate far more power than onshore wind turbines, offshore wind power could meet Europe's energy demand seven times over highlights the Global Wind Energy Council (GWEC). While in the United States, offshore wind has the potential to provide four times the energy capacity needed.
The rapid growth and potential of offshore wind is best represented in Europe. Currently, more than 90 percent of the globe's offshore wind power is installed off the coast of northern Europe. As of this entry, Europe has a total of 4,336 MW generating from 1,503 offshore wind turbines at wind farms located across 10 countries. Looking ahead, the European Union has set a goal to generate 20 percent of its electricity from renewable sources by 2020, and offshore wind is slated to play a major role in making that a reality.
In spite of the higher costs and the uncertainties involved in
offshore wind, research in this sector has been significant,
and the main reason is the potential offered by offshore wind
turbines, especially in lands close to water length of coastline of India including the coastlines of
Andaman and Nicobar Islands in the Bay of Bengal and
Lakshwadweep Islands in the Arabian Sea is 7517 km.
Length of Coastline of Indian mainland is 6100 km.
Thorough Wind studies have to be carried out along the
coast to identify the prospective offshore wind farm sites.
Based on these studies a Pilot project can be started by
MNRE which will help as a Demonstration project
Dr.A.Jagadeesh Nellore(AP),India
Wind Energy Expert
E-mail: anumakonda.jagadeesh@gmail.com

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