PrintStep 3
Instructions
Next, get the model to calculate how much energy we would need in total. This is easy — all you have to do is choose the global population limit and the history of per capita energy demand and the model combines these. You may choose whatever population limit you like. You may also change the per capita energy demand from the default, but it will cost you money, and you’ll have to keep track of that money (the model will keep track of it for you). The model does this by first calculating the total energy demand without any conservation (called the reference global energy demand in the model), using the default graph of per capita energy demand and the population — then we subtract from that the reduced energy demand (you need to lower the per capita energy demand curve) to give the amount of energy conserved (see page 12 of the graph pad). Next, the model takes this energy conserved and multiplies it by the unit cost of conserved energy, which is 0.5e9$/EJ (McKinsey, 2010) to get the conservation costs. Compare this unit cost of conservation to the unit costs of making energy from different sources by clicking on the Energy Costs button in the upper right of the model window, and you’ll see that conservation is a great deal. There is an upper limit here of 40% reduction from the reference curve, according to estimates from McKinsey (2010), so you can't push this too far. In fact, if you try to conserve an unrealistic amount, the model will override you and keep the actual per capita energy to within the 40% limit. Once you’ve got the total energy demand, the model subtracts the energy production from fossil fuels to get the energy that has to be supplied by renewables (non-fossil fuel sources).
The video below, Capstone Project Step 3 Instructions, will take you through the steps involved in this part of the project.
Video: Capstone Project Step 3 Instructions (4:24)
PRESENTER: In this next step in this project, we're going to calculate the total energy demand. And we're going to do that simply by combining the population part of the model with the per capita energy curve here. So this shows the per capita energy in terms of exajoules of energy per billion people over the history of this model. Runs over about 200 years. And this is a graphical function of time that can be changed, and we'll change that here in just a second.
So if we run this model now, let's go back here to the beginning and run this model in time and see what happens. OK, here's our carbon emissions curve here, here's our global temperatures, so we are getting close to keeping it below three. Now if we go backwards here, here's our graph showing the global energy demand. Also the reference global energy demand. They're one in the same here because I haven't made a change to this curve here.
Also shown on here is zero right now is the energy conserved. So if I go ahead and change this curve here and lower the energy demand, that represents conservation of energy. So let's go ahead and do that. Make a little bit of a change here. Let's say we lower the energy demands through time like this. And on this graph, this line over here at the edge represents the year 2200. This line over here represents the year 2010. Every little increment here represents an additional 48 years, I think. OK, so we can adjust this history.
So I've have made some big steps energy conservation. Let's see what happens and we'll run the model. And sure enough the global energy demand is less than this reference value here. And the difference represents energy conserved. Now this energy conserved isn't free. It comes with a cost. And so later in this model you'll see the costs that are attributed to this conservation of energy.
And you can look at that if you just go back here to page five and you can see this pink line here, conservation costs. It's very, very low here. It looks like a flat line not changing. It's actually changing a little bit, but it still just stays a very, very low. So that's a very modest cost.
The other thing you can do, of course, in adjusting this model is to lower the population limit. So let's lower the population limit from something like 12 to something down near 9. We run the model and you see that everything gets shifted downwards. The reference curve gets shifted downwards, the actual global energy demand gets shifted down, and the energy conserved shifts down as well. So these two controls, population limit and per capita energy, are how you determine what the global energy demand is.
Step 3 Deliverables
NOTE: Skip these deliverables until you've cycled through Steps 1-6 and found your ideal scenario. Then produce the following:
A graph showing the reference global energy demand and actual global energy demand and the energy conserved (page 12 of graph pad), along with the conservation costs.
A graph showing the global energy demand, the carbon-based energy, and the renewable energy (page 2 of graph pad). Both of these graphs should appear in your summary poster.
A brief statement of what you chose for a population limit, and what kinds of challenges (if any) you think might be involved in achieving this population limit. This should be positioned next to the graph above.