Power-to-gas

Key takeaways

Power-to-gas belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Power-to-gas to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Power-to-gas from memory before moving on to harder problems.

Reference excerpt

Power-to-gas (often abbreviated P2G) is a technical process that uses electric power to produce a gaseous fuel, sometimes referred to as an electrofuel. Most P2G systems use electrolysis to produce hydrogen. The hydrogen can be used directly, or further steps (known as two-stage P2G systems) may convert the hydrogen into syngas, methane, or LPG. Single-stage P2G systems to produce methane also exist, such as reversible solid oxide cell (rSOC) technology. Produced gas, just like natural gas or industrially produced hydrogen or methane, is a commodity and may be used as such through existing infrastructure (pipelines and gas storage facilities), including back to power at a loss. However, provided the power comes from renewable energy, it can be touted as a carbon-neutral fuel, renewable, and a way to store variable renewable energy.

Power-to-hydrogen All current P2G systems start by using electricity to split water into hydrogen and oxygen by means of electrolysis. In a "power-to-hydrogen" system, the resulting hydrogen is injected into the natural gas grid or is used in transport or industry rather than being used to produce another gas type. ITM Power won a tender in March 2013 for a Thüga Group project, to supply a 360 kW self-pressurising high-pressure electrolysis rapid response proton exchange membrane (PEM) electrolyser Rapid Response Electrolysis Power-to-Gas energy storage plant. The unit produces 125 kg/day of hydrogen gas and incorporates AEG power electronics. It will be situated at a Mainova AG site in the Schielestraße, Frankfurt in the state of Hessen. The operational data will be shared by the whole Thüga group – the largest network of energy companies in Germany with around 100 municipal utility members. The project partners include: badenova AG & Co. kg, Erdgas Mittelsachsen GmbH, Energieversorgung Mittelrhein GmbH, erdgas schwaben GmbH, Gasversorgung Westerwald GmbH, Mainova Aktiengesellschaft, Stadtwerke Ansbach GmbH, Stadtwerke Bad Hersfeld GmbH, Thüga Energienetze GmbH, WEMAG AG, e-rp GmbH, ESWE Versorgungs AG with Thüga Aktiengesellschaft as project coordinator. Scientific partners will participate in the operational phase. It can produce 60 cubic metres of hydrogen per hour and feed 3,000 cubic metres of natural gas enriched with hydrogen into the grid per hour. An expansion of the pilot plant is planned from 2016, facilitating the full conversion of the hydrogen produced into methane to be directly injected into the natural gas grid.

In December 2013, ITM Power, Mainova, and NRM Netzdienste Rhein-Main GmbH began injecting hydrogen into the German gas distribution network using ITM Power HGas, which is a rapid response proton exchange membrane electrolyser plant. The power consumption of the electrolyser is 315 kilowatts. It produces about 60 cubic meters per hour of hydrogen and thus in one hour can feed 3,000 cubic meters of hydrogen-enriched natural gas into the network. On August 28, 2013, E.ON Hanse, Solvicore, and Swissgas inaugurated a commercial power-to-gas unit in Falkenhagen, Germany. The unit, which has a capacity of two megawatts, can produce 360 cubic meters of hydrogen per hour. The plant uses wind power and Hydrogenics electrolysis equipment to transform water into hydrogen, which is then injected into the existing regional natural gas transmission system. Swissgas, which represents over 100 local natural gas utilities, is a partner in the project with a 20 percent capital stake and an agreement to purchase a portion of the gas produced. A second 800 kW power-to-gas project has been started in Hamburg/Reitbrook district and is expected to open in 2015. In August 2013, a 140 MW wind park in Grapzow, Mecklenburg-Vorpommern owned by E.ON received an electrolyser. The hydrogen produced can be used in an internal combustion engine or can be injected into the local gas grid. The hydrogen compression and storage system stores up to 27 MWh of energy and increases the overall efficiency of the wind park by tapping into wind energy that otherwise would be wasted. The electrolyser produces 210 Nm3/h of hydrogen and is operated by RH2-WKA. The INGRID project started in 2013 in Apulia, Italy. It is a four-year project with 39 MWh storage and a 1.2 MW electrolyser for smart grid monitoring and control. The hydrogen is used for grid balancing, transport, industry, and injection into the gas network. The surplus energy from the 12 MW Prenzlau Windpark in Brandenburg, Germany will be injected into the gas grid from 2014 on. The 6 MW Energiepark Mainz from Stadtwerke Mainz, RheinMain University of Applied Sciences, Linde and Siemens in Mainz (Germany) will open in 2015. Power to gas and other energy storage schemes to store and utilize renewable energy are part of Germany's Energiewende (energy transition program). In France, the MINERVE demonstrator of AFUL Chantrerie (Federation of Local Utilities Association) aims to promote the development of energy solutions for the future with elected representatives, companies and more generally civil society. It aims to experiment with various reactors and catalysts. The synthetic methane produced by the MINERVE demonstrator (0.6 Nm3 / h of CH4) is recovered as CNG fuel, which is used in the boilers of the AFUL Chantrerie boiler plant. The installation was designed and built by the French SME Top Industrie, with the support of Leaf. In November 2017 it achieved the predicted performance, 93.3% of CH4. This project was supported by the ADEME and the ERDF-Pays de la Loire Region, as well as by several other partners: Conseil départemental de Loire -Atlantic, Engie-Cofely, GRDF, GRTGaz, Nantes-Metropolis, Sydela and Sydev. A full scale 1GW electrolyzer operated by EWE and Tree Energy Solutions is planned at the gas terminal in Wilhelmshaven, Germany. The first 500 MW is expected to begin operation in 2028. Wilhelmshaven can accommodate a second plant, bringing total potential capacity to 2GW.

… excerpt ends here. Continue reading the full article.

Illustrations

Power-to-gas: Power-to-syngas feedstock is the same as feedstock derived from other sources. — Power-to-syngas feedstock is the same as feedstock derived from other sources.

Worked examples

Example 1 — a first encounter with Power-to-gas

Start with the simplest possible case. Write down what Power-to-gas claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Power-to-gas before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Power-to-gas ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Power-to-gas

In research: Power-to-gas appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Power-to-gas in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Power-to-gas is common in secondary-school and first-year university syllabi. It links to neighbouring topics Energy conversion, Energy storage, so understanding it makes those chapters shorter.
In everyday life: Look for Power-to-gas outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Power-to-gas in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Power-to-gas means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Power-to-gas out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Power-to-gas in simple terms?

Power-to-gas (often abbreviated P2G) is a technical process that uses electric power to produce a gaseous fuel, sometimes referred to as an electrofuel. Most P2G systems use electrolysis to produce hydrogen.

Why does Power-to-gas matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Power-to-gas?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Power-to-gas.