It’s hardly a secret (conspiracy theory aside): greenhouse gas emissions – with carbon dioxide (CO2) in particular – related to human activity are involving alteration of Earth climate which starts having an evident impact and is expected to lead to dire consequences. And the solution to the immediate problem is severe: cut CO2 emissions to zero within 2050.
To this aim – without compromising the current living standards – it’s essential to address the problem on several fronts. First of all, it’s essential to reduce energy waste and, in parallel, a gradual but quick revision of energy management concept is required in civil, industrial, transport and power generation sector, as well as in the information and communication technologies one.
Policymakers vacillate, as confirmed by the failure to reach an agreement between the almost 200 countries gathered a few weeks ago in Madrid for the 25th UN’s Conference of Parties on climate changes (COP25). But new and promising solutions for energy transition come from the scientific community and the industrial world. Efficient exploitation of renewable energy sources, CO2 capture technologies from power generation and industrial plants, smart grids for domestic use and much more.
But the transport sector is probably the most problematic one. And in this sector, the so-called “e-fuels” can play a key role. The E-fuel definition is very simple: it’s a liquid or gaseous fuel (such as methanol, hydrogen, methane, dimethyl ether, but also synthetic oil and diesel) produced not from fossil sources but from renewable electrical energy. But why are e-fuels so important today?
Let’s begin with a statistic. Every year, in Europe, about 480 TWh of electrical energy from renewable sources is wasted due to the non-programmability of the source, since solar and wind energy is frequently produced when not necessary. Just to make the idea, it’s the same amount produced by 150 medium-scale power plants and near twice the net electrical energy produced in Italy in 2018 (about 280 TWh, according to Terna data). And it is about 13% of the European energy demand: 3,631 TWh in 2018, according to data recently published by the International Energy Agency. This energy waste is a very serious problem: this overproduction involves the instability of the electric grid – which limits a further diffusion of renewable energy plants – with just a partial reduction of CO2 emissions, since conventional power generation plants must be kept as hot reserve – continuing burning fossil fuels and emitting CO2 – in order to provide electricity if the production from renewable sources becomes lower than the demand.
The role of the e-fuels
In this contest, e-fuels can allow solving two problems at the same time: first of all, they allow storing the overproduction of electricity in chemical form, with the subsequent stabilization of the electrical grid and promoting a further exploitation of renewable sources; in parallel, they use carbon dioxide produced from fossil sources, generating a circular economy based on carbon, seen as a resource instead of a problem. And this is not limited to the power generation sector, but also to several kinds of industrial plants.
The key solution is provided by the so-called “power-to-liquids” or “power-to-gas” technologies (on the basis of the final product), which use the overproduction of renewable energy to produce hydrogen. This gas can react with CO2 captured from other applications – and, in the future, directly from the atmosphere – to be thermochemically converted into liquid or gaseous fuels. And it is also noteworthy that e-fuels are cleaner than the most famous biofuels (and, of course, than the corresponding fuels from fossil sources): less soil and water exploitation during production processes and less particulate, carbon monoxide and nitrogen oxides during combustion.
If the first scientific work on power-to-gas has been published in 1994 (a Japanese study focused not on the containment of global warming but on as a technical solution to a specific water problem), the development of power-to-liquids/gas technologies has gained momentum in the last 15 years, with the leading role of Europe.
The most significant power-to-liquids application is today the “George Olah Renewable Methanol Plant”, operating since 2011 near Reykjavík (Iceland), and managed by Carbon Recycling International. The unit converts every year some 5,500 tons of natural CO2 (from volcanic source) into 4,000 tons of methanol, sold in northern Europe with the trade name of Vulcanol®, indicative on the origin of the product.
As for power-to-gas is Europe the leading country. The most important application is Audi’s plant in Werlte, north-west Germany, which produces every year some 1,000 tons of methane from little less than 30 GWh of renewable energy.
Summarising: the technologies are available and demonstrated in existing plants. So, what is missing for their commercial diffusion? The first response is of a technical nature: these processes are characterized by low conversion efficiencies, involving the need for gas recirculation to obtain an acceptable conversion. The second response is economic: e-fuels production has hydrogen production as a first step and capital costs of such a section impacts for about 50% of the investment for the plant as a whole. Therefore, a strong effort from the policymakers is required to adequately incentivise the diffusion of these technologies and further development of the technology is asked to the scientific community to optimize the process and reduce the costs.
This is one of the main focuses of Sotacarbo Research. First of all, advances catalysts are currently under development for e-fuels production from renewable energy and CO2. One of these catalysts, characterized by surprising performance, is the objective of an international patent application. In parallel, a new experimental plant is currently under design to set and optimise the whole process for the production of liquid and gaseous fuels (methanol and methane in particular), in collaboration with ENEA, the Italian National Agency on New Technologies, Energy and Sustainable Economic Development. The new plant, funded by the Italian Ministry of Economic Development within the Research on Electric System programme, will be commissioned within 2021 and it will represent an international reference point in the development of power-to-liquids and power-to-gas technologies. Alberto Pettinau