d hydroelectric power currently generates over 16 percent of the world’s electricity.
These Landsat images show the site of the Three Gorges Dam in China, which is the largest hydroelectric dam in the world. The dam is over 2,300 meters (1.4 miles) long and forms the straight line across the river in the second image. The project became fully operational in 2012 and has a power generation capacity of 22,500 megawatts. The reservoir created behind the dam stretches 600 kilometers (373 miles) along the Yangtze River and provides water storage for downstream flood control along with electric power.
The Landsat image from 1993 (left) shows the area one year before construction began. The 2013 image (right) was acquired one year after the power plant became fully operational. The second image shows the reservoir created by the dam and the higher water level that now extends into many side valleys. Also visible in the 2013 image is a lock system that supports shipping traffic, as the increased depth and width of the river now permit larger ships to travel this area.
As hydroelectric power continues to expand around the world, Landsat imagery can help monitor the land surface changes and impacts caused by these projects.
The Topaz Solar Farm is one of the largest solar farms in the United States. Located in central California, the 550-megawatt power station consists of 9 million solar panels across 9.5 square miles (24.6 square kilometers). Construction began in 2012 and was completed in late 2014, and the site can now produce enough electricity to power 160,000 homes.
These images, acquired by Landsat 7 and Landsat 8, show the area of the solar farm development. The 2011 image was acquired before construction started and shows that the previous land use was agriculture. The 2015 image shows the completed project. In the second image, the agricultural land use (green blocks) has been replaced by the solar installation (dark blocks). This second image also shows less overall greenness, due to seasonal change.
Landsat images such as these can help document changes to the landscape, as alternative power sources are being developed to provide renewable energy for the Earth’s growing population.
Wind Power in Texas, United States January 20, 2015
Wind power is produced by using large generators to harness the kinetic energy of wind. It is gaining importance as a large-scale source of renewable energy, and new wind farms are being developed worldwide.
In the Texas Panhandle of the United States, an area previously known for fossil fuel production is undergoing a rapid surge in wind energy development. One example is the Longhorn North Wind Project, which was initiated in late 2013 and expected to be fully operational in 2015. When completed, the installation will provide approximately 200 megawatts of power from 100 wind turbines. The area covers almost 57 square kilometers (22 square miles), and is only one of many new wind farms that are being developed in this region of Texas.
These two images show the Longhorn North Wind Project area in December 2013 and one year later in December 2014. The irregular white lines in the later image are access roadways that support construction of the new wind turbines and connection to major transmission networks in the area. The small bright dots on those roadways represent individual turbine locations.
Another change in the later image is an increased number of green fields and small lakes filled with water. In September 2014, remnants from a tropical storm brought heavy rain to this part of Texas, which had been in a drought since 2011.
As wind energy sources continue to expand in the United States and worldwide, Landsat imagery will be useful for monitoring the land changes associated with this development. The consistent, repetitive images from Landsat can also provide a valuable record of the weather- and climate-induced influences as they occur on the Earth’s landscape.
The Sampson Flat Fire started on January 2, 2015 near Adelaide, Australia. Hot, windy weather during the Australian summer