We now move on to the assessment of wind energy resources. In this video, we'll look at considerations when forecasting wind energy production. We'll be taking a look at global wind speeds, both onshore and offshore, regional wind speeds in wind power, collecting wind data, we'll look at an example with finding required wind data, specifying a wind turbine, and estimating turbine energy production, and finally, we'll take a brief look at commercial wind analysis products. This map shows global wind speeds around the world at 100 meters. It's from the onlined resource Global Wind Speed Atlas and there's another site with great information about wind speeds. As you can see, wind speeds vary greatly around the world. The dark purple is where the speeds are the greatest and the blue are where there's the least amount of wind. You can see that along coastlines and near coastlines is where we find the greatest wind speeds. This is a map of offshore wind speeds. You can see the shorelines have very attractive wind speeds around the world. It's part of the interest in the growing interest in offshore wind. There's also good regional information from the Global Wind Atlas. Let's go to County Kildare, Ireland. Here's a map of County Kildare. You can see it's just west of Dublin. This chart shows wind speeds at 50 meters in height, and in County Kildare, the wind speed is about 7.58 meters per second, pretty good wind. From the Global Atlas, we can also get power information. Again, this is at 50 meters and we can see that the watts per meter squared at this altitude in this location in County Kildare is about 527 watts per meter squared of turbine area. A lot of good information on this website. But because local conditions vary so much due to terrain, surface roughness, and so forth, we cannot rely on a wind atlas for our data. In these cases, we need to do it ourselves. We undertake what's called a wind measurement campaign to determine wind speed and direction, wind shear, turbulence, and roughness, air density, and humidity. We typically will use meteorological met mast such as those to the right. They're ideally at the same height of planned wind turbines, but they can be lower and we can adjust them upwards. Anemometers for wind speed at different heights, usually, recording weathervane for wind directions, barometers, thermometers, humidity sensors, and the data is recorded in a data logger. Very frequently this data is collected for one or more years because winds vary so much during the year. We want to know the mean wind speed and distribution, we want to know the wind rose, that is, what direction the wind blows from and how frequently, we want wind shear and turbulence, and we want air density, pressure, and temperature all to be able to better understand the power output that we can get from a particular site. Let's take a look at a hypothetical example for evaluating energy potential of a wind site. The wind study produces the following measurements we suppose; the site elevation is 200 meters above sea level, the anemometer height is 10 meters, the mean temperature at the site is 15 degrees centigrade or Celsius, the mean wind speed is seven meters per second, and the wind shear parameter is 0.15. This is a measure of the surface roughness. Looking at the chart on the right, we see that we're operating in tall grass on level ground, so our parameter is 0.15. This is a lookup. For our hypothetical example, let's suppose that we settle on a Vestas V80-1800 wind turbine, like the one shown to the right, one or more, depending on how many turbines are going to be on our farm. This turbine has a rated capacity of 1.8 megawatts, it has an 80-meter rotor diameter, and we're going to assume 90 percent uptime, that's typical for most wind turbines. Vestas gives us this power curve. We see that the cut-in speed velocity is about four meters per second for wind speed, it achieves its full rated capacity at about 15 meters per second, and the cut-out speed is about 30 meters per second. This is all good information. Let's estimate the annual turbine energy output of our hypothetical example. Here's a screenshot of a spreadsheet that I built. It's available for your use online in the resources section of this video. You can see that we've chosen the Vestas VAT turbine. We plug in the numbers that we've looked at before, seven meters per second for the mean wind speed, 15 degrees centigrade for the mean site temperature, and so forth, and the spreadsheet automatically calculates the energy out, in this case, 7,332-megawatt hours annually. It also will show you the profile of energies given wind speed. The blue is wind speed, the red is energy production. You can see that most of the energy produced by this turbine and any other is for higher wind speeds, very little production of energy below seven meters per second. Beyond that is where most of our production occurs. This is exactly what we've seen before in previous videos, high wind speeds have much more energy than the low wind speeds. In addition to doing it yourself, there are a number of online services and commercial services to help you out with your wind analysis. One of these is a wind farm assessment tool out of Denmark. Danish are some of the first people who actually exploit wind energy, and so they have lots of good information on this site. Another is Metrodyne out of France. You can see this is a picture of some of their software that helps you with analysis of wind assessment as well as where to place your turbines. In this video, we've examined a number of considerations when forecasting wind energy production. We've taken a look at global wind speeds, both onshore and offshore, we've taken a look at regional wind speeds in wind power. But once we get down to some locality, we're going to have to collect our wind data on our own. This requires wind data, wind turbine specification, and estimated turbine production. Finally, we took a brief look at commercial wind analysis. In the next video, we look at hydro-power. We'll see you there.
