The Power of X – not talking here about the Marvel mutant superheroes, but about technologies that can help us to fight climate change.
Southwestern Iceland, 2011: the George Olah plant marks a milestone for CO2 utilisation from carbon capture and storage. We finally have the first industrial-scale power-to-x (PtX) facility, able to exploit carbon dioxide waste gas for the production of renewable methanol. PtX technologies are often described as crucial for reducing CO2 emissions, given their suitability for combining energy from renewable sources and captured CO2 that leads to a potential carbon-neutral fuel life cycle.
But what’s behind these terms? And can they contribute to climate neutrality?
The analysis and insights collected by the International Energy Agency (IEA) in the World Energy Outlook 2019 highlighted an ever-greater gap between the promise of energy for all and the sad reality of almost one billion people still with no access to electricity.
The scientific evidence is clear on the need for faster cuts in greenhouse gas emissions, but expectations of rapid energy transitions based on renewable energies, collide with hard facts. And energy systems highly dependent on fossil fuels are still real today.
The World Energy Outlook shows a few scenarios that explore different possible futures, the actions – or inactions – that determine them and the interconnections. The current policy scenario shows that energy demand is expected to rise by 1.3% every year in the next two decades, leading to the damaging combination of an unstoppable growth of energy-related emissions and energy insecurity. The transition to a more sustainable energy system needs to include low emission energy supply technologies such as renewable energy sources (RES). In recent years, RES technologies have made significant progress in the technical and economic fields with a substantial increase in installed capacity.
However, the natural intermittency of most forms renewable energy slows down their large-scale implementation. This behaviour afflicts the balancing of the overall electrical system. When energy production exceeds demand, you need technologies that allow both the accumulation of the excess energy produced, and its reuse. This is precisely where PtX technologies come into play.
PtX can convert electricity (power) into other forms of energy (X) through reversible chemical reactions. A classic example of PtX is the electrolysis of water for hydrogen production. According to the Future of Hydrogen report, published by the IEA in June 2019, the supply of hydrogen to industrial users is a global business. To meet the growing demand and to ensure that its production does not increase CO2 emissions, the electrical energy for the reaction must come from renewable sources.
Green hydrogen, produced by renewables, is a fundamental building block for the production of synthetic fuels. It can react with CO2 to produce methane, methanol and dimethyl ether. This reaction is called hydrogenation. The carbon required for the synthesis process can be obtained from recycled CO2, for example, captured from abundant sources such as fossil fuel power plants or from the air itself. These carbon capture and utilisation (CCU) methods see CO2 as a resource, not as a waste.
Conversion of hydrogen to the most convenient forms of liquid and gaseous energy carrier facilitates long distance transportation and extended periods of storage, with minimal or no losses. Besides, all synthetic fuels can fit directly into existing infrastructure (e.g., filling stations and the gas network) without facing high costs, technical barriers or changes in habit.
A positive impact is expected not only in transport but also in many other sectors, where synthetic fuels can be used as final carriers of energy and raw materials: industry, electricity production, heating, chemical raw materials, fuel cells. Being able to create a carbon dioxide capture unit next to a fuel production site, thereby exploiting the distribution network already in place, would reduce production costs and would bring synthetic fuel costs into closer alignment with conventional fuels.
The first laboratory-scale power-to-gas plant, for the production of methane from hydrogen, as built in Japan in 1996. Nowadays, Europe leads the sector mainly thanks to Germany, Denmark, the Netherlands and Switzerland.
CO2 methanation projects are mostly taking place in Germany; due to the transition of the country towards a renewable energy system, associated with a growing demand for chemical storage of electricity and the need to compensate the intermittent supply of wind and solar energy. According to the German Energy Agency (Dena) the implementation of PtG technologies in Germany would lead to a 55% reduction by 2030 and 80-95% in the long term.