By Jonas Reichert
Energy has driven the development of civilisation since its beginning. The harnessing of fire allowed us to utilize more energy from food. Later the power generated from coal enabled the industrial revolution, and fossil fuels like oil and gas kickstarted the age of transportation. The world’s energy demand is still growing, while the damages done by fossil fuels become ever more apparent. Renewable energy sources could ease that for some time. All these sources are ultimately driven by the sun. But to meet the ever-growing energy demand, we need to harness the sun’s energy directly.
The Kardashev scale is a tool to rank the technological advancement of a civilisation based on the energy it uses. A Type I civilisation would be able to harness all energy available on its host planet, a Type II civilisation all energy of its star and a Type III even all the energy of its entire galaxy. Humanity would currently not even reach the first level on that scale. Reaching even the first level seems like a far-fetched utopia. But, surprisingly, the scientific concepts for the first two levels are already here. We just have to convert them into technology.
To be considered a Type I, humanity would need to convert the entire power flux of the sun, which delivers roughly the total equivalent of the world’s annual energy consumption in one hour. Traditional renewable energy generation methods, like solar cells, hydropower or biofuels, are not able to achieve this while humanity is still planet bound. But we are not bound to use the sun’s energy directly, if we can mimic the sun’s energy production here on earth. This idea has been around for decades and is now already to be tested on a large scale. Nuclear fusion promises to solve most of our energy problems without causing environmental damage and producing waste that has to be stored for millennia.
Just like nuclear fission, fusion uses the fact that atomic nuclei are bound to the core at different degrees of tightness depending on the number of protons and neutrons in its core. For light cores up to iron in the periodic table, the cores become bound together tighter in heavier cores with more particles. For heavy cores beyond iron the opposite is true, and lighter cores are bound tighter. In fission reactors we use the latter fact by splitting a heavy nucleus in two lighter ones and capturing the released energy. In fusion reactors, however, we go the opposite way and build a new nucleus from two light ones like hydrogen and capture the released energy again.
This process can provide a large power generation rate, but is technically difficult to do. The two atomic nuclei must come very close to each other to fuse, but they are electrically charged and repel each other. To overcome this barrier, the raw material is heated up to several million degrees Celsius until it forms a plasma, a state of matter similar to gas, but in which all electrons are unbound from the nuclei. In this form it has the necessary energy to start fusion but must be confined by a complicated set of strong magnetic fields. In the best case, after the initial heat up, the plasma can sustain its temperature and can produce an energy surplus continuously. Unlike fission reactors, it does only produce small amounts of low-radioactive material and cannot cause a meltdown, as if the confinement fails, the diluted plasma will touch the wall and cool down quickly.
The International Thermonuclear Experimental Reactor (ITER), currently built in Caradache, France, promises to be the first fusion reactor to run an energy surplus for a longer period of time from 2025. Should this experiment be successful, commercial fusion power plants could become reality in the second half of this century. Employed on a large scale, fusion power could satisfy humanity’s energy demand for millions of years. Enough time to prepare to leave earth.
Leveling up even further would require us to leave our planet. Several different processes have been brought up to provide the energy necessary for a Type II civilisation, but the most feasible is probably the creation of a megastructure, also called Dyson sphere, around our sun to harness the energy of our host star directly. These would give humanity access to, from today’s point of view, nearly unlimited energy and would enable many other utopian projects, like interplanetary colonisation, transforming entire planets into habitats for life, or even interstellar travel. And from a pure scientific perspective, it is not only possible, but easy.
A Dyson sphere would not be a solid sphere, as this would be too unstable and vulnerable to impacts, but more like a swarm of satellites surrounding the sun. Even though it would be possible to use traditional solar cells to collect the energy, a much more feasible solution would be to concentrate the light using large mirrors and use this to heat up water. A steam turbine can then convert the energy into electricity. This technique is already used on earth today and therefore easy to develop and deploy. The produced energy is transferred, in converted form, to wherever it is needed. Concentrated light like emitted by a laser would make a decent choice.
We also already have a plan ready to build this Dyson sphere. A lot of advanced technology is needed in the process, but none of it is out of reach and, at the point at which we are thinking about building a Dyson sphere, this problem should be sorted. In the first step, we will need a lot of energy to bring equipment into space, but as we are a Type I civilization now, this is no problem. Unfortunately, the sun is very big – its diameter is 109 times that of earth – so we need an enormous amount of raw materials. A good source is actually located in the vicinity of the sun. So we have to disassemble Mercury, to which no one should be too attached, and build our mirrors out of it. This process should be highly automated, but to be completed, an amount of energy is required which even an advanced civilisation will hardly be able to provide. But if one builds the Dyson sphere step by step, the energy of the first parts can be used to further fuel the construction. The premade panels could be launched into space using a giant railgun, which is easy considering Mercury’s low gravity and lack of atmosphere.
With our Dyson sphere ready and Mercury gone, the human future is only constrained by our dreams and the laws of physics. It is a difficult undertaking, and will require global cooperation, but it is a challenge worth taking, to open up possibilities beyond our imagination and truly leveling up humanity.
By Jonas Reichert
Illustration: Mireia Lundquist
