I had the chance to go talk with a wonderful and smart bunch of 5th graders at Oran M. Roberts Elementary School about solar energy. I have been interested in solar energy for over two decades now. It started as a cub scout; we built small solar powered cars, which were made from a 1 foot square piece of plywood with four wheels and a small motor attached to a small solar cell. It only worked in clear and direct sunlight and went very slowly, but solar power has improved a lot over the last 20 years!
So what is solar energy? It’s everything - all energy comes from the sun or other stars. Fossil fuels come from microorganisms that used the sun for energy and now we use the solar energy they stored. Wind comes from the sun. The sun heats part of the earth, creating the wind.
Solar energy even helped create the heat at the core of the Earth. After the death of a few stars, the Solar System started to form. The planetary nebula helped create a little blue green planet with an iron nickel liquid core. That core and its rotation create what we know as geothermal power.
People have been using solar power for years without even realizing it. Every time you turn off the light in a room and use the natural light coming into the room to read, you’re using solar power. When you go out in the sun to get warm, that’s solar power too.
To put it all in perspective:
The graphs above show the energy use in the USA in 2008.
Coal, natural gas, nuclear and renewable energy are mostly used for electricity.
Petroleum is used mostly for transportation. Renewable energy only make up 7% of our energy and solar energy only 1% of that.
Solar power is mostly used for residential and commercial power and not for transportation or large-scale electrical generation.
Over the next 20 years, solar is projected to grow.
What are the advantages of solar energy? Well after you get the solar cells installed, you don’t have to pay for the energy. Also, collecting solar power produces no pollution. You can put solar cells on nearly everything, and it can work anywhere there is sunlight, which can be great if it is somewhere far off the grid, or you don’t want to spend the resources to attach it to the grid.
However there are some disadvantages to solar. The largest one is that solar power is dependent on the sun. This means that solar panels cannot generate electricity when it is dark. That’s 12 hours or so a day that the solar panels can’t work. Weather also effects solar power. It may not work if it’s cloudy or rainy outside. Also, the land cost for large solar power generation stations are large. Solar 2, a large scale solar thermal power station out in the Mojave Desert, used 891,000 ft² of land to produce up to 10 megawatts of power.
Currently electricity produced by solar plants is more expensive than most other sources.
Types of solar collectors:
Concentrated (Dish) solar – the panels are made into a parabolic shape to concentrate the light collected into a sensor.
Flat Photovoltaic cells – these are what most people think about when they think of solar power. These cells are what you usually see connected to street signs or on top of buildings. They use their surface area to collect light instead of concentrating it into one sensor.
Stay tuned next week for when I reveal the exciting Q and A from the students at Oran Roberts. I’ll tackle such questions as “Does solar power work on other planets?” and “What countries outside the USA use solar power?”
So be here next week, same bat time; same bat channel.