WHAT ARE POWER-TO-X AND E-FUELS?

Interest in alternative fuels, power-to-x and e-fuels continues to grow as companies focus on reducing their environmental footprint. For this reason, many varieties of e-fuels are now being used in power generation and other applications.?

To begin with, we must first know the definition of power-to-x and e-fuels.

What is power-to-x?

Power-to-x refers to a series of techniques and pathways for converting, storing and utilizing renewable electrical energy. Power-to-x is specifically applied when there is excess renewable electricity produced from solar or wind resources. Rather than being wasted (the industry-specific term for this is "curtailed"), the excess electricity is used productively. The "x" can refer to a variety of energy carriers or uses. Power-to-hydrogen is the generation of hydrogen using renewable electricity. Power-to-power refers to the storage of electricity in batteries. Power-to-heat is the use of electricity to heat a home or business, usually in conjunction with a storage heater. The meaning of power-to-methane should be easy to guess.

What are e-fuels?

E-fuels are fuels that are synthesized using renewable electricity, often using inorganic feedstocks. They are the "x" in power-to-x when "x" is a fuel. E-fuels include liquid and gaseous hydrocarbons such as methane and various gasoline- and diesel-like fuels, alcohols such as ethanol and methanol, and non-carbon fuels such as hydrogen and ammonia.?

Why do we need electronic fuels and power-to-x?

Power-to-x decouples electricity generation and electricity demand. At every instant, the total amount of electricity generated in an electricity grid must exactly match the total amount of electricity used by consumers. In other words, generation and demand are usually closely related. If generation cannot meet demand, for example, if too many power plants are running at the same time, the power grid can quickly collapse. Counterintuitively, the same is true if generation exceeds demand. When large amounts of variable renewable energy resources, such as wind and solar, are online, renewable generation can quickly exceed demand. When this occurs, renewable resources are curtailed to avoid system collapse.?

In some markets, the spot price of electricity can, as a result, turn negative when renewable generation is high. This means that market participants are paid to use more electricity.?

Power-to-x projects take advantage of excess and off-peak renewable energy to produce something useful. It's a win-win situation: power-to-x producers can buy cheap, renewable CO2-free electricity, and solar and wind farms can sell electricity that would otherwise have been lost.?

The e-fuels produced in a power-to-x project can be used hours, weeks or months later to produce electricity.?

E-hydrogen, for example, can be used in a business equipped with a fuel cell and solar panels to generate electricity during the evening and night. Companies can use this configuration to reduce the demand rates charged by the electric utility to consumers with high peak demand.?

For electricity consumers, e-hydrogen is a way to reduce their carbon footprint beyond what can be achieved with solar panels and wind turbines alone. For utilities and grid system operators, e-hydrogen is especially valuable because it is one of the few CO2-free ways to balance intermittent variable renewable energy resources.

The benefits of using e-fuels are not limited to the power generation application. They can be used in vehicles and other industrial sectors to great advantage. E-hydrogen powered forklifts are one e-fuel application that has become popular in the logistics sector, and e-hydrogen forklifts tick several boxes. They have little downtime. They generate no fumes or exhaust fumes, and in an enclosed environment such as a warehouse, this feature is important. And they are CO2-free.

Beyond e-hydrogen, liquid e-fuels have a different process to be produced, which is more complicated. These liquid e-fuels are especially useful for powering heavy-duty applications, such as marine applications.?

For applications where hydrogen is not a practical option, several alternative e-fuels can be synthesized using hydrogen. Here are some of the main ones:

What is e-methanol?

It is a commodity used on a large scale in the chemical industry to produce a variety of substances. Methanol is sometimes referred to as wood alcohol and has long been used as a fuel in specialty vehicles such as RC aircraft, dirt bikes and, yes, monster trucks. Several processes have been developed to synthesize methanol using CO 2 , hydrogen and renewable electricity. Their product is a clean, carbon neutral energy carrier: e-methanol. There is growing interest in the use of methanol as a fuel. Methanol and e-methanol could help tugboats, fishing boats, ferries and other vessels using specially modified engines comply with increasingly stringent regulations limiting NOx and sulfur emissions in densely populated coastal areas and, in the case of e-methanol, can also lower their carbon footprint.

What is e-methane?

The main component of natural gas, it is a widely used fossil fuel. In the United States, methane is the number one energy source used in power generation. Methane and natural gas are also increasingly popular fuels for motor vehicles. A methane power system combines an e-hydrogen production process with CO 2 to produce e-methane without carbon emissions. Several e-methane production processes are being developed and industrialized. Outside of power generation, the mining sector has shown much interest in these processes. For mines located in remote areas, the cost of trucking in gasoline or diesel can be prohibitively high. These mines can potentially save a lot of money by fueling their heavy trucks with e-methane on site, using locally generated renewable electricity.

What is e-diesel?

Companies and research institutions around the world are developing processes to mass-produce liquid hydrocarbons from CO 2 and water using e-hydrogen. The production of synthetic gasoline, turbosine and diesel is envisaged. An advantage of these e-fuels is that they can be used as a direct fuel in standard engines, making CO2-neutral operation possible without the need to modify vehicles or the fueling infrastructure.?

What is e-ammonia?

Ammonia is another very common chemical. The fertilizer industry uses it in large quantities, and has seen occasional use as a fuel in specific situations. Belgium, for example, converted city buses to run on ammonia during World War II (the buses were scrapped as soon as fossil fuels became available again).?

On the other hand, e-fuels show promise, but have yet to overcome challenges that prevent widespread adoption. In almost all cases, production costs are the main issue. Outside of certain specific use cases, there are often other low-CO2 alternatives available with which e-fuels must compete. Biofuels and electric batteries have an advantage in that regard, as they have been on the market longer.?

However, costs will come down as e-fuel technology matures and scales of production increase. To draw a parallel, the cost of lithium-ion batteries (the type used in electric vehicles and most stationary energy storage) has fallen by 98% in the last 30 years. If e-fuels experience a fraction of that progression, it won't be long before you can find them at your local gas station.

Finally, the power-to-x business has a role to play in meeting the needs of the various alternative fuels. In addition to the fuel itself, you also need to consider local availability, regulations and your use case. These additional factors complement the unique benefits offered by each alternative fuel.

Adopted from: Cummins INC. (2021).