A device that uses CO2produces neutral jet fuel from sunlight and air has proven itself on the roof of a Swiss lab. Parts of this technique had already been tested before. Now the entire system has been put to the test. a CO2-neutral jet fuel industry is thus one step closer.
At present, aircraft that burn kerosene make a significant contribution to the release of harmful greenhouse gases. Aviation is responsible for about 3 percent of global human-caused CO2emissions.
Researchers from the Swiss university ETH Zurich have built a mini solar refinery that should provide a solution for this. The fuel they produce with this produces just as much CO . during combustion2 when the machine takes out the air to make that fuel. The fuel can therefore net CO2– be neutral.
In addition to demonstrating the technique, the researchers spend in their publication also pay attention to the possibilities for scaling up their solar refinery.
Synthetic Jet Fuel
The fuel device has been on the roof of an EHT laboratory building for the past two years. The whole consists of three parts. First of all, there is the so-called direct air capture module, that CO2 and draws water from the air. Furthermore, the device contains a component that captures and uses solar energy to convert CO2 and convert water into syngas, a mixture of carbon monoxide (CO) and hydrogen gas (H2). Oxygen is created as a residual product. The final component is a gas-to-liquid technology, which can turn the syngas into jet fuel kerosene, methanol or other types of hydrocarbons.
The latter part uses the so-called Fischer-Tropsch process, which was used decades ago to make synthetic fuels. Previously, no CO . was used for this2 from the air, but for example gasified coal. Now that there is a demand for sustainable, synthetic fuel, there is renewed interest in this process. The difference is that researchers are now looking at fossil-free production of syngas.
Over the past two years, the solar refinery has demonstrated that it is technically feasible to make synthetic kerosene from water and CO2 from the air, with the help of solar energy. It successfully went through all the steps of this process. On an average ‘working day’ of seven hours – with varying solar radiation – the mini-solar refinery produced 32 milliliters of methanol.
Solar Refinery in the Sahara
Based on this prototype, the researchers calculate that it is possible to meet the worldwide demand for aviation kerosene with this technique. This requires approximately 45,000 square kilometers of solar refineries. That sounds like a lot, but – the researchers calculate – it is ‘only’ 0.5 percent of the Sahara.
According to the researchers, the Sahara and other desert areas are particularly suitable for such solar refineries. After all, there is enough sun and you do not have to compete with agriculture or livestock for the use of land. However, it will be necessary to check whether sufficient water is available.
If this process is indeed scaled up to an industrial level, the costs for the kerosene will be approximately 1.20 to 2.00 euros per liter, according to the researchers. That cannot yet compete with the current prices for fossil kerosene. Government support in the form of subsidies will therefore be needed to literally and figuratively get this synthetic kerosene off the ground.