# Homework Help: Fossil Fuels and Energy

1. Oct 30, 2015

### TheMathNoob

1. The problem statement, all variables and given/known data
Today, globally, only 2% of our energy comes from carbon-free energy sources. If we continue economic and population growth in a business-as-usual scenario, what % of our energy needs to come from carbon-free sources if we want to stabilize our atmosphere at 450 ppm? [Use your answer from Q4, to calculate the %].
Answer from Q4= 14.7 tetrawatts are required to stabilize at 450ppm in 2050

2. Relevant equations

3. The attempt at a solution
I really think that I have to find the amount of energy that carbon-free sources have in average.
I am using this model http://forecast.uchicago.edu/kaya.html

2. Oct 30, 2015

### billy_joule

What is Q4?

3. Oct 30, 2015

### TheMathNoob

sorry question 4. Question 4 asked me to find the required energy to stabilize the atmosphere at 450ppm in 2050. I did that with the model of the link in the description.

4. Oct 30, 2015

### billy_joule

It doesn't require energy to stabilize atmospheric C content (and your answer isn't energy either..)
Can you post the question word for word? It's hard to offer assistance without the full story.

5. Oct 30, 2015

### TheMathNoob

That's the whole question. I calculated the 14.7 tetrawatts by using the model in the description of the problem. If you set the model in the mode carbon-free energy needed , you will realize that in 2050, 14.7 tetrawatts of energy are required to stabilize the atmosphere at 450ppm.

6. Oct 30, 2015

### billy_joule

14.7 Terawatts of power.
The problem would be more accurately stated as something like:
'To maintain projected global power consumption and also stabilize C at 450ppm how much carbon free power must be produced in 2050?'

Anyway, I get 7.144 Terawatts, which may be because we are using different growth rates, I left them at the default, all zero.

Back to your original question; To find what percent of C free power is of total power; You know C free power already and the total power can be found on the (mislabelled) total energy production graph.

7. Oct 30, 2015

Thanks!!!