Why gas is essential to the energy revolution

These days, everyone involved in discussions about the future of the energy system agrees that it is both desirable and feasible to make that system largely renewable by 2050, despite the diversity of the participants – oil majors, nuclear companies, companies active in renewable energy, experts such as the International Energy Agency (IEA), ministers of state for energy, and non-government organizations focused on environmental protection. Having myself participated in many such discussions over the past year (at Davos, CERA Week, etc.), I am struck by the growing consensus around this issue.

While everyone agrees on the destination, however, the route that leads there is far from clear.

The challenges are many, with no obvious solutions. To give just a few examples, how can we minimize the economic and social impact of the energy transition? How can we prevent existing infrastructures, and even those built during the early years of the transition, from becoming stranded assets for local governments and managers, at a significant cost to all of us? How can we overcome the intermittent nature of renewable energy sources?

Personally, I believe that the viability of the energy transition also depends on one essential source of energy: gas.

Natural gas today, green gas tomorrow. This belief is borne out by expert scenarios for the energy transition and the new strategies being adopted by the energy sector. As the Financial Times stated in an article entitled "Big Oil bets on a dash for gas," published in early September, “Companies that once treated gas as the poor relation to ‘black gold’ are now gambling that the colourless commodity can help secure their future in a decarbonising world.”

This may seem surprising, since gas is still counted among the fossil fuels.

There are, however, several arguments suggesting that gas will be the keystone to the energy revolution. Today, that means natural gas is the best complement to intermittent renewable energy and the best substitute for polluting energy; and tomorrow, once we have the technology and have made it affordable, green gas will be a necessary prerequisite to a 100% renewable energy system.

A replacement for polluting energy sources

Let us first consider the scenarios developed by experts (AIE, ADEME, Negawatt, etc.) to keep global warming below 2°C: they all rely heavily on natural gas to quickly decarbonize the energy system.

Experts believe that, initially, it will be necessary to substitute gas for coal in electricity production.

This is because gas-fired plants emit much less CO2 and nitrogen oxide than coal-fired plants (as much as 80% less) and almost no particulates.

This should cause demand for natural gas to grow, particularly in non-OECD countries, which have high energy needs and are increasingly concerned about their air quality and thus the health of their citizens. In China, for example, 60% of electricity is still produced using coal. The country’s goal is to increase the share of natural gas from 6% to 15% of its total energy consumption by 2030.

Gas should also play a major role in decarbonizing the transportation sector, which is responsible for 23% of global CO2 emissions. While the sector uses oil-derived fuels to meet 95% of its need, there are mature alternative fuels that pollute much less. Replacing oil with compressed natural gas (CNG), which is used for fleets of buses, taxis, and trucks, and liquefied natural gas (LNG), which is used for international road transportation and maritime fleets, would quickly and significantly reduce emissions of CO2 (-25%), nitrogen oxides (-60% to -90%), particulates (-95%), and sulfur oxides (-100%).

It is very likely that this substitution will accelerate in coming years in the maritime sector, as tougher regulations on the sulfur content of fuels are adopted.

An ally for renewable energy

Natural gas is also poised to play another essential role in the energy transition, namely supporting the increasingly massive integration of renewable energy sources, most of them intermittent, into the energy system.

What is intermittent energy? Its production is variable, not continuously available, and out of our direct control. It depends on external resources and often has no correlation with demand. This is true of solar power (from sunshine) and wind power. In the United Kingdom, for example, the proportion of solar energy in the electricity produced over a single day can range from 20% on a sunny summer day to nearly 0% on a dark winter day.

In an energy system that relies more and more on intermittent renewable energy, the question of balance becomes crucial.

How can we ensure that needs are always met when production varies rapidly, significantly, and to some extent unpredictably?

It’s certainly possible to imagine a system that is 100% renewable and electrical, based entirely on variable renewable energy sources like wind or solar. But in that case, the only way to cover consumption requirements at any time of day would be to invest massively in gigantic storage solutions, excess production capacity, new transmission lines, etc. These investments come at a cost, which is passed along on consumers’ bills – and still, such a system would not prevent either waste or breakdowns. During times of surplus, the extra power produced would be dumped, assuming the production was not simply shut down, and during times of high demand, the system could be thrown out of balance.

Between massive investments, additional costs to consumers, breakdowns and waste, the scenario based on 100% renewable electrical power is far from optimal until we are better able to manage intermittence.

Conversely, continuing to use natural gas would maintain balance in the electrical system at no additional cost to the population as a whole. The infrastructure is already built and can serve as a fully controllable underground hub not only to supply customers directly (with hot water, heat, or for industrial purposes) but also to quickly launch combined cycle power plants that produce electricity directly (Gas to Power) with a high output, thus providing a secure solution for peaks in electrical consumption. Above all, this solution has the benefit of using gas infrastructures that have already been largely paid off, thus avoiding costly investments.

Natural gas makes it possible to gradually and substantially increase the proportion of intermittent renewable energy in the energy mix without triggering breakdowns in the electrical system.

Gas goes green

But does this mean that the energy system will never be entirely renewable, because we will always need gas to serve as its backbone?

It may well be possible to achieve a scenario based on 100% renewables. Gas is already somewhat green today, and it could become completely green—with zero CO2 emissions—by the 2050s.

First thanks to biogas and biomethane produced from organic waste and biomass. Trials are currently being conducted in an attempt to produce green gas from microalgae. Another possibility is renewable hydrogen, produced by electrolysis of water using renewably generated electricity in a process known as Power to Gas.

A circular economic model

Beyond its role in stabilizing the system, gas also opens the door to an energy configuration that operates according to the principles of a circular economy: a system that eliminates waste and surplus, since both are systematically converted for other purposes.

Consider the example of biomethane. It begins with waste (from agriculture, industry, households, food processing, etc.) that places a load on the environment and generates a cost to those responsible for processing it. By allowing that waste to decompose in an anaerobic enclosure, we can produce a renewable source of energy, namely biogas. That biogas can then be purified into biomethane, more commonly known as “green gas,” and injected into the gas network or used to supply the power system with heat, electricity, or fuel. In fact, as of several days ago, we now offer French households a natural gas package in which 10% of what they consume is certified “green gas, produced in France.”

The hydrogen example also demonstrates how a problem – what to do with production surpluses from renewable energy – can be transformed into an opportunity. Rather than simply dumping surpluses, it is possible to convert the power produced into hydrogen via electrolysis of water and then use it for a variety of purposes: energy storage, mobility, electricity generation, industrial products, or injection into the gas network.

This type of management of production surpluses from renewable energy could be implemented across an entire region. For example, the ENGIE Group and its independent subsidiary GRDF are involved in an experiment along these lines in the Dunkirk region. The GRHYD project is designed to transform the surplus electricity generated by renewable sources into hydrogen, which can then be either injected into the natural gas transmission network or used to develop a fuel used by a fleet of buses.

On a large scale, hydrogen even offers a solution to the intermittence problem of renewable energy sources by allowing for a fluid, coordinated interchange between the gas and electrical systems. Power to Gas is currently the best massive storage solution for surplus energy production. With these solutions, surpluses of renewable electricity can be stored for long periods (Power to Gas followed by underground storage), and then be converted back into electricity (Gas to Power) during times of peak demand. Again, this model uses gas to support a circular system in which both surplus and waste are systematically transformed and reused.

That is why gas is essential to the energy transition today and why, once it has become 100% green by the 2050s, it will be a mainstay in the renewable energy mix and circular economy of the future.

Gas paves the way for a more balanced energy system and a more harmonious world.