State Electricity on Google Earth: How many Solar Panels would it Take?
This activity has students calculate electricity use by state and determine how much land would be required to replace all sources of electricity with solar panels. Students also consider costs and land-use trade-offs.
ContextThis activity could be used from high school to upper year college/university.
This activity is part of a course. It could be used as a weekly lab exercise in a university course.
- Students develop competence using Google Earth as a tool for gathering information and making calculations and proposals.
- Students develop their quantitative skills.
- Students gain an appreciation for the nature of trade-offs when considering different sources of electricity.
Activity DescriptionStep 1. Students use a .kmz file in Google Earth to calculate electricity consumption for a state or states, and then calculate the area needed to effectively replace all electricity power sources with solar panels. The .kmz file, geocommons.com/maps/27351.kmz, shows electricity consumption per 100 people in million kilowatt-hours per year, so students have to research population of states and do a simple calculation.
Step 2. The students do independent research to determine the quantity of power generated per panel, the spacing of panels, and possibly solar intensity. Depending on the nature of the course and the type of students, the instructor could provide some of this information or leave it open-ended for students to solve.
Step 3. Students use Google Earth to find a possible area in a given state. They would have to take into consideration what area (can't use inaccessible mountain tops, for example), land use in terms of what the proposed area would be replacing, and economic feasibility. Students would also compare costs of installing solar panels to the current costs of electricity in their state. They would use a provided map of the U.S. to determine their state's typical insolation. For example, in New Jersey, a typical solar panel produces about 10 watts per sq. foot, or about 107 watts per sq m. Insolation is about 4.6 Kwh/msq/day would need a 2.25 Kw system for 500 Kwh/month usage. The costs are $10 000 Canadian/installed KW for small domestic systems. So the cost would be about $15K+. To compare costs for electricity in their state as of today, we have attached another GE file that posts the cost in dollars per million btu of electricity by state. btu can easily be converted to kwh to compare final cost of solar panels array vs cost of current electricity.
Step 4. Students submit an overlay map showing proposed area of solar panel installation, a brief description of their calculations and another description of their proposal, including the reasoning behind their choice of location for the solar panel array and the cost of the array.
AssessmentA rubric is used to assess the accuracy of the calculations and the quality of the submitted discussion.
- Retail Electricity Prices and Expenditures by State, USA, 2005 (KMZ File 440bytes Apr18 11)
- geocommons.com/maps/27351.kmz - showing electricity consumption per 100 people in million kilowatt-hours per year
- State Electric Profiles from the Energy Information Administration's electricity section
- Teaching with Google Earth