Floating Offshore Wind Data Mapping Activity

 ? Question

How can floating offshore wind help meet electricity demand when other renewables are not available?

 Background

We don’t use electricity at the same rate at all times during the day. The amount of electricity that we need all the time is called baseload power. It is the minimum amount of electricity that is needed 24 hours a day, 7 days a week. However, during the day at different times, and depending upon the weather and other factors, the amount of power that we use increases by different amounts. We use more power during the week than on the weekends because it is needed for offices and schools. We use more electricity during the summer than the winter because we need to keep our buildings cool. An increase in demand during specific times of the day or year is called peak demand. This peak demand represents the additional power above baseload power that a power company must be able to produce as needed. When we consider locations for installing equipment to harness renewable energy, we must carefully study the resources available and the energy demands of the region. In this section, we will analyze the wind and solar resources on the west coast of the U.S. and the electricity demands in the adjacent areas.

Electricity Demand

On a typical day, the electricity demand starts to go up around 5 a.m. when people begin waking up to get ready for school and work. Demand goes up even more in the afternoon as people start to go home to make dinner and relax for the evening, but businesses remain open. Later in the evening, the demand begins to drop off as people go to bed for the night and businesses shut down. (See Figure 1)

Diurnal Cycles

A diurnal cycle is any pattern that recurs every 24 hours as a result of one full rotation of the Earth around its own axis. Both solar and wind energy are impacted by diurnal cycles.

SOLAR IRRADIATION PATTERNS

Electricity generation from photovoltaics (solar panels) depends on having enough solar irradiation or radiation from the sun. This varies by latitude, season, and cloud cover. The timing of solar irradiation and the timing of electricity demands are key considerations. See Figure 2 for an example of the pattern of solar irradiation experienced in some parts of California.

Figure 1: Average hourly electricity load during a typical day by region in different seasons. Data from EIA.

Figure 2: Average monthly solar irradiance in northern and southern California in 2019. Data from The National Solar Radiation Database

Average Monthly Solar Irradiance in 2019

W/m 2

100 90 80 70 60 50 40 30 20 10 0

JanuaryFebruary March April May June July AugustSeptemberOctoberNovemberDecember

Southern CA Northern CA

OFFSHORE WIND PATTERNS

During the day, the air above the land heats up more quickly than the air above water. The warm air over the land expands, becomes less dense and rises. The bigger the temperature difference, the faster the air from over the ocean moves in to replace the rising air over the land. So, as the day goes on the wind speed increases until the land begins to cool again after sunset. See Figure 3.

SOLVING THE DUCK PROBLEM

Photovoltaics have been installed in rapidly increasing numbers in some parts of the country over the last several years. Since photovoltaics only generate electricity during daylight hours, this source of electricity has created a new challenge for regional Independent System Operators (ISOs) who help manage the demand. It is the responsibility of the ISO to coordinate, monitor, and control the operation of our electrical power systems to keep electricity flowing and meet the ever-changing demand in the most financially responsible way possible. The “Duck Problem” refers to the shape of the curve when electricity demand is plotted against time-of-day for areas where a lot of solar has been installed. The way demand drops dramatically during midday when sunlight is most intense, then rises sharply as the sun begins to set in the sky, resembles a swimming duck. The curve shows electricity demand for the California Independent System Operator (CAISO) on any typical spring day, plotted against time. Several years’ worth of data are plotted on the same set of axes. As more families and businesses install solar systems on their buildings, the midday demand for electricity drops further.

The U.S. Department of Energy identified three solutions to the Duck Problem in their video, “What is the Duck Curve?” The first solution is to add flexibility to the electrical power system. The second is to incentivize the reduction of evening energy use, and the third is to develop systems to store excess solar energy that can be harvested during the day. Time-of-day electricity rates, that charge less in the morning and more in the evening, are how utilities can incentivize reducing energy use in the evening. Systems such as pumped storage hydropower, batteries, and other storage mechanisms are being researched and incorporated by several government and private organizations across the country. Floating offshore wind helps tackle the Duck Problem by adding flexibility to the system. Watch the video: https://youtu.be/KwA44fr7apw.

Figure 3: Diurnal power output for six different 6 MW offshore wind turbines in six locations during the month of March, 2016. Data from BOEM.

Figure 4: California ISO, “What the duck curve tells us about managing a green grid”, 2016. Data from CAISO.

MAPPING INFRASTRUCTURE

Geographic information systems (GIS) are used to gather, manage, and analyze data that can be linked to a location. GIS lets us view vast amounts of data in ways that helps us make sense of it and use it to tell stories.There are a number of great websites that use GIS to share energy information. Let’s start by exploring some of these: 1. Navigate to the U.S. Energy Atlas at https://atlas.eia.gov/pages/energy-maps. Then go to “All Energy Infrastructure and Resources”.

What energy infrastructure is near you? In the upper left corner is a search box. Type the address of your home or school so you can see the energy infrastructure near you. What did you find? Gradually zoom out so you can see your whole state.

Did you see anything that surprised you? Do you notice any patterns? Click on this button to see what the different symbols on the map represent.

Click on this button to view a list of types of energy infrastructure included on this map. From here you can remove items from the map by clicking on to make it easier to find the features you are most interest in.

2. Let’s investigate features that you think are important to consider when planning an floating offshore wind farm. For this exercise we will consider possible locations on the California Pacific Coast. Navigate to https://caoffshorewind.databasin.org/maps/new/ to begin.

Click to zoom in closer. What kind of data do you think needs to be considered when decisions are made about the locations for offshore wind turbines?

Click and search for data layers that you think are important. Enter your search term, select the dataset(s) you want, and click “add items”.

If one data layer is covering and obscuring another, experiment with the transparency of your top layer:

You can also experiment adding the layers in a different order.

When you are ready to share your map, click on this icon and select “PDF”. Share your PDF as instructed by your teacher along with a brief written summary of what you have learned by analyzing this spatial data with your classmates.

Conclusion

1. What energy infrastructure did you discover around your home or school? How difficult would tying a wind turbine to that infrastructure be? Explain your answer.

2. What data sets did you think are important when considering offshore wind farms?