Integration of Renewable Technologies and Power-to-X

A tool for better renewable integration

What are the challenges of the electricity grid today?

As the penetration of renewable technologies increases in our electricity grid, the concern for the stability of the grid has substantially increased. A grid that was designed for large, centralized and fairly predictable power plants is not well-suited for the integration of distributed, and inherently variable renewable energy. Not only that, on the demand-side increased variability is also expected. As the existing ‘consumers’ transition to ‘prosumers’ – back-feeding electricity into the grid such as in the case of rooftop solar PV.

Moreover, there is also an observable shift happening from day-night demand characteristics i.e. demand is becoming more and more flexible (and in some cases unpredictable) with the electrification of various sectors. A case in point being electro-mobility, where high power loads can be connected anywhere and anytime to the grid. These paradigm shifts from the conventional way the electricity was produced and consumed has compounded their adversarial impacts; necessitating a redesign of electrical infrastructure with modern considerations in mind.

What are Integration Strategies to tackle the challenges of today’s grid?

From a technical perspective, the variability can be effectively reduced by two key integration strategies, i.e. temporal and spatial integration. “What does that mean?”, one might ask.

Simply put, storages can be used to store the electricity when it is not needed and then withdrawn from the storage when it is actually demanded (temporal offset). Or, large transmission infrastructure can be constructed that can transport electricity efficiently and economically over large distances from where it is generated to where it is consumed (spatial offset). These two strategies can compensate for demand and generation variations, weather fluctuations and unexpected faults in the grid.

The importance of storage as a measure to relieve grid instability is already established. The pumped hydro projects are exclusively used for grid balancing and generation offset purposes. Moreover, newer technologies such as Li-ion batteries, flywheel, compressed air storage are making rounds in different commercial and pilot projects – with varying levels of technical and commercial success.

Continental grid projects such as DESERTEC and ASEAN Power Grid are an example of connecting large land masses to improve the electrical demand and production characteristics. Even though the EU Super Grid also serves this purpose, more or less, this was never envisaged to be its operating modality. The EU Super Grid was originally designed to provide balancing power among neighboring countries for grid stability under the IGCC platform; instead of high-volume energy transport. Thereby, reinforcement of cross-border interconnections was proposed under EU Green Deal to account for higher cross border energy flow, paving the way for a more integrated EU internal energy market.

So Müncon, how can we better integrate RE into our energy infrastructure so that the decarbonization targets are effectively met?

By means of sector coupling:

The challenges faced can be greatly resolved by connecting the electricity sector with different sectors, such as: transport, heating, and fuel production. This approach is known as ‘sector coupling’ and is enabled by various ‘Power-to-X’ (P2X) technologies – mostly focusing on fuel generation and substitution. The conversion of electricity to a ‘X’ medium enables the ‘storage’ and ‘transportation’ of electricity using infrastructure other than electrical grid. This not only limits unnecessary grid extensions and reinforcements, but also, enables further sectors which cannot be readily electrified to indirectly transition to renewable energy; wherever the technical and economical hurdles can be overcome.

What are key Power-to-X (P2X) technologies?

Key P2X technologies most relevant to energy applications are:

Power-to-Mobility – P2M

P2M is by far the most recognizable P2X technology. This technology deals with the electrification of the personal and goods transport. The electricity is used to charge the electric vehicles (EVs) which are then utilized for transport. In principle, this makes them a mobile energy storage device. A complementing technology to P2M is Vehicle-to-Grid (V2G), where the stored electricity in the EVs is used to supplement the grid.
Power-to-Hydrogen – P2H2

Hydrogen can be produced using electrolysers in the P2H2 technology. The hydrogen gas produced from renewable electricity is referred to as ‘green hydrogen’. The green hydrogen can be directly used in multiple applications, such as: electricity production, seasonal storages, heating, transport and can also serve as a feedstock for liquid and gaseous fuels production. Given the properties of hydrogen, combustion in a turbine or engine as well as electricity generation in a fuel-cell are technically feasible. Additionally, hydrogen can also substitute natural gas in the existing gas networks.
Power-to-Heat – P2H

Heating and cooling needs are necessary for industrial, commercial and residential sectors. In P2H technology the electricity is used to produced heat (or cooling) by the means resistive heaters, heat pumps or air-conditioners. This heat can be used to space or process heating (or cooling) and can also be stored in thermal storage for later use.
Power-to-Gas – P2G

P2G technologies use electricity to produce gaseous fuels to be used in downstream application. Over the recent year, gas has emerged as a key energy carrier in the electricity, transport and industrial sector. Hydrogen produced by electricity is used as a primary feedstock for the production of Syngas, Methane or Liquidized Petroleum Gas (LPG). The generated gases can be incorporated into existing supply chains and storages – providing additional flexibility and opportunity for renewable energy consumption
Power-to-Liquid – P2L

Syngas produced by P2G technology can be used to produce liquid fuels by means of Fischer-Tropsch Process or Methanol synthesis. P2L can enable bulk transport of RE in the global energy markets. Moreover, it also promises decarbonization of aviation and shipping sectors with relative ease; without the need for disruptive changes in the existing infrastructure. In line with this, it proposes an alternative to electromobility, in which existing ICE-based vehicles can use liquid fuels produced by P2L technology – extending the life of existing vehicles.

What is the status of Power-To-X?

Even though these technologies have demonstrated technological competence, the biggest hurdle to large scale commercial deployment is economics and efficiency. Theoretically, these technologies assume a surplus of renewable electricity in the grid, which can be used to generate and store varied energy products while the electricity is cheap. And, then use the produced energy products to meet the later demands.

This abundance of renewable electricity also theoretically covers the low conversion efficiencies of these technologies. However, this is not the case as the grid is still largely dependent on fossil-fuels, and conversion and then reconversion neither makes technical nor economic sense.