This post is part of blog action day. Those participating in blog action day are supposed to “Publish a post on their blog which relates to an issue of their own choice pertaining to the environment.” Blogging about the environment shouldn’t be too hard; most of my posts are about the environment. What can I blog about today? Hmm… Al Gore won some award for doing nothing. But everyone and their mom has already blogged about that. Maybe European Cities Tackling Climate Change? Sounds too much like a football game. No, I’ll be taking on a slightly larger problem. I’m going to solve the world’s energy problems with this single blog post. Sound too good to be true? Read on.

The population of the world is increasing incredibly fast, as seen below. With the addition of more people to the planet, our energy demands also increase. In and of itself, an increase in energy demand is not a big problem. The problem lies in the fact that a large percentage of our energy supply is in the form of non-renewables such as coal and oil. There seems to be a lot of politics with respect to the issue of peak oil, but sooner or later we’re going to run out. If that time comes before an alternative form of energy is found, it won’t be pretty. I’m going to suggest solar power, and will show here basic, “back-of-the-envelope” calculations regarding solar power.

Let’s fast-forward to sometime in the future, and make a few assumption:
1. there exists solar panels that can be used as a road surface
2. every building has full coverage of solar panels on their roofs
3. the city of Tucson will stay the same size in area (ha, not likely)
4. the city experiences urbanization and not sprawl

The result may be that there are effectively solar panels that cover the entire ground the area the size of Tucson. How much power would this city-power plant produce? According to the US Dept of Energy (DOE), solar photovoltaic resource potential for Tucson is around 7 kilowatt-hours per square meter per day. The area of Tucson is 505 square kilometers. After some unit conversion and multiplication, that comes out to producing 3.535E9 kWh per day or 1.3E12 kWh per year. (Note: 1EX is scientific notation, and means a one followed by X number of zeros. 1E12 is one trillion.)

The DOE estimated that in the year 2000, the United States consumed 95 quadrillion (95E15) BTU of energy. I’m not sure why they use the British Thermal Unit, so more conversion in neccessary. 95 quadrillion BTU is equal to 2.78E13 kWh. Therefore, in one year (2000) the United States consumed 3.171E12 W. By comparison, the world energy consuption is 1.5E13 (15 terawatts) per year in 2007.

Therefore, if an area the size of Tucson were devoted entirely solar panels, it would produce about 10% of the world’s energy needs. Said another way, it would take an area of about 5050 square kilometers covered with solar panels to completely power the planet. That’s about the size of Connecticut - pretty small. But that’s assuming some as-of-yet fictional solar panel. Let’s look at what a real panel would do.

For this example, I will be using specifications from one particular GE solar panel. This panel produces a peak power of 200W. Let’s assume for a typical sunny day in Arizona, this particular cell outputs 170W at solar noon on the equinox. Because it’s dark for half the day, and the sun angle changes throughout the day, the cell will produce about 20% of its rated maximum power, or 34 W averaged over the entire day.

These particular panels are 1485mm by 981mm. To figure out how many solar panels will needed, we divide the average output power for the cell by its area. This comes out to 2.334E7 W/km2. If we take the total world power consumption and divide it by 2.334E7 we get the total area of solar panels needed to power the world! It comes out to 642700 km2. This is a big area - roughly the size of Alaska!

We can also calculate how much it would cost. One of these panels costs $1099. Dividing the cost of each panel, by it average power output, we see it costs about $32.33 per watt. Multiplying this value by total world power consumption yields a cost of about $500 Trillion!

Clearly it would cost an extraordinary amount of money to use solar power for 100% of our energy needs. And it would cover a super-large area of the planet. But the good news is that it doesn’t need to happen all at once. The American Southwest has large portions of sparcely populated land, and has low amounts of cloud-cover year round. It would make a perfect area for large-scale testing of current solar technologies.

(No Ratings Yet)

 Loading ...

Related Posts:

Trackback URI |