If you look at collection of aluminium waste and recycling rates, you can see that for some applications they're already quite well established: for cars, for construction, for infrastructure. Those collection systems seem to be in place in many parts of the world, and recycling rates for those applications are already quite high. They can go even above 90% in some parts of the world. The global recycling rate for all aluminium applications are estimated at 40 to 70%. So they could be improved, but already they are among the highest if you look at the other metals. So here there is some good possibilities, although, for some specific applications, a lot of effort still needs to be done. Most of the aluminium applications have a long life span and this has consequences of course for the stock dynamics. Applications in buildings or in infrastructure have a lifespan of up to 50 years and that means that the outflow out of the stock, the present stock, which is the material that's available, for recycling, is the inflow of 50 years back. And then the demand was still very much lower. So the outflow now is much less than we would need to supply the present demand. So that is something that we have to consider when going towards a circular economy. Now, what assumptions did we make in our Scenario for circular economy for aluminium? We focused on only a few driving forces. The first one is population. We have assumed that it will increase to 9 billion and that it will stabilize at that level around 2050. This is a prerequisite for a stabilizing demand. As long as the population keeps on growing, the demand also will keep on growing and we will not reach a saturated stock level. Then we have set the per capita demand for aluminium at stock level on a saturated stock of 450 kilograms per capita. This is based on, well, some very rough estimates on well, what people have now in more developed parts of the world, and we have assumed that the rest of the world will sort of grow to the same level. As the average residence time for aluminium, we have chosen 30 years. This is, sort of, an in-between, between the very long lifespans of the construction applications and the very short ones of the aluminium cans. We did not make specific assumptions on technology or policy. We just explored the possibilities of recycling rate. We set the recycling rate at 50%, and then at 90%. So we calculated both those possibilities. And from these data, we can calculate the total saturated stock and flows in an equilibrium situation, per capita and total. So it's a quite limited set of assumptions where there is no value change, no politics, no geopolitical situations involved. It's only to explore, well, how long actually does it get, does it take to get from where we are now to a situation where we can have an equilibrium? When we have an equilibrium stock size of 450 kilogram per capita and a residence time of 30 years, then the equilibrium demand is 15 kilograms per capita per year. So that's what we used. And if you size this up, so multiply it with the global population, the total worldwide demand for aluminium is 135 million metric tons per year. And the stock size, the equilibrium, saturated stock size is 4050 million metric tons. And then the next assumption, of course, is what fraction comes from secondary production? Well, the assumption here is that 50% and 90% are recycled. You can see both lines in this graph. And you can also see the difference in outcome between that. And that will start right now, but of course, because of the delay, because of the long life span of aluminium, the amount of secondary production is presently still quite small, even if 90% is recycled. So the amount of scrap available is also shown in this graph. It's the green line. Then the red and light blue lines represent the amount of scrap that is actually recycled and has turned into new aluminium again. The dark blue line is the demand. You see that it still rises rapidly. Even after 2050, it keeps on rising because the stock has not reached the saturated level, yet in many parts of the world. And about 2100, you can see that it sort of has stabilized. So it needs a century from now to actually stabilize the demand and therefore allow secondary production to keep up with it and even that moment is not reached yet in 2100. So it takes longer than a century to establish a closed loop economy where a large part of the demand is fulfilled by secondary production. Now, we have to get back to the challenge. And the challenge had to do with energy. So what difference does this make for energy use? Well, if we don't recycle anything, the energy use for aluminium production will grow to a level of 250% of the present level, annually. At a recycling rate of 50%, this is 150%, so it will still grow, but not so much. And if we, recycle 90% of the scrap, then it can actually be reduced to 30% of the present level. So even with a much increased demand level, still the amount of energy used for the production can be reduced to 30% and that means that the circular economy is the most effective option of meeting the aluminium challenge. Well, we have used scenario analysis now to see whether we can find a good way out of the aluminium challenge and we have explored different options for that. First one, reduce the amount of energy use per kilogram of aluminium, does not seem very well possible, as long as we keep on using primary production, at least. The second one, reducing greenhouse gas emissions from energy use. That offers some options. There is quite some gain to be made. The third one, substitution, well, this we have to see case-by-case whether it makes sense or not. You cannot say that in advance. And the last one, the circular economy, that is really the one that seems to be most effective. Here we can increase at aluminium use while decreasing the amount of energy used. Secondary production uses much less energy. Therefore, the circular economy is really a good way out. Of course, these are not predictions. These are just assumptions. So whether it will work out like that, we don't know. A prerequisite, for example, is the demand stabilizes. Well, whether this happens and when it happens and at what level it happens, we made some assumptions about, but this can also work out quite differently. But it is possible, due to the high potential recycling rates, to reduce primary demand significantly, even with a much increased stock in use. And this will also reduce energy requirements, even to below the present level. We can say, though, that it will take time and effort. It will not happen before 2100 because the assumptions that we made are quite optimistic. And even then, only if we start closing the loop right now. So this is really a very important message, also, to policy makers. If we want to go to a circular economy, which we might want to because it seems to be very effective, then we need to start now and keep in mind, that even then, it takes a long time before we actually get there.
