For most of the past two decades, the energy transition has been measured in gigawatts.
Governments announced renewable deployment targets, developers competed to build larger wind and solar projects, and investors focused on levelised cost reductions and capacity pipelines. Success was defined largely by one question: how quickly fossil generation could be replaced by clean electricity.
By 2026, that framing is beginning to look incomplete.
Across Europe, North America and China, policymakers and system operators are confronting a less visible but structurally more important challenge. The issue is no longer simply generating clean electricity. It is maintaining stable electricity systems in the absence of the conventional synchronous machines that historically held those systems together.
It is in this context that Germany’s introduction of a dedicated inertia procurement mechanism, known as Momentanreserve, becomes significant. At first glance it appears to be a technical market adjustment designed to address declining system inertia. In reality, it may represent something more fundamental: the beginning of a process in which electricity markets start to explicitly price the physical properties that underpin grid stability.
For decades, those properties were effectively invisible. They were embedded within coal, gas, hydro and nuclear generation, delivered automatically by rotating machinery that provided inertia, fault current, voltage support and system strength as a by-product of producing electricity. Markets paid for energy, not for the physical characteristics that made energy delivery possible.
That assumption is now breaking down.
The End of “Free Stability”
As renewable penetration increases and synchronous generation retires, the services that were once abundant are becoming constrained. Solar PV, wind turbines and battery storage systems connect to the grid through power electronics rather than directly through rotating mass. While these technologies can provide stability services under certain conditions, they do not inherently replicate the system-wide physical behaviour of synchronous machines.
The consequence is a structural shift in how power systems operate. Stability is no longer a free by-product of generation. It is becoming something that must be explicitly procured.
Germany’s Momentanreserve mechanism is one of the first attempts to formalise that reality within a market framework. Its purpose is to ensure sufficient fast frequency response in a system where traditional inertia is declining. But its broader significance lies elsewhere. It represents the point at which a major electricity market begins to assign economic value to a property of physics that was previously taken for granted.
Once that principle is established, the logic extends quickly. If inertia has value, then system strength has value. If system strength has value, then voltage stability, fault current contribution, oscillation damping and black-start capability also acquire economic relevance. What were once treated as engineering requirements begin to resemble marketable services.
The Great Unbundling of Electricity
This marks the beginning of a deeper structural change: the unbundling of electricity systems into their physical components.
A gas-fired power plant once provided multiple functions simultaneously. It generated electricity, stabilised frequency, supported voltage, contributed fault current and strengthened the network. One asset delivered multiple system services. One revenue stream supported them all.
The emerging power system is fundamentally different.
Electricity generation is increasingly separated from stability provision. A battery may provide fast frequency response. A synchronous condenser may provide fault current. A STATCOM may provide reactive power. A grid-forming inverter may establish voltage and frequency reference. A demand-response platform may provide balancing reserves.
What was once bundled within conventional generation is becoming a collection of distinct services procured independently.
This process resembles transformations seen in other infrastructure sectors. Telecommunications evolved from vertically integrated monopolies into layered markets for connectivity, bandwidth and data services. Electricity appears to be undergoing a similar evolution.
The consequence is profound. Future power systems may be valued not solely according to how much electricity they generate, but according to the quality of their electrical behaviour.
A megawatt may no longer be just a megawatt. Its value may increasingly depend on how it contributes to system stability.
Europe’s Emerging Stability Economy
Europe is leading this transformation.
The reasons are straightforward. No major region combines high renewable penetration, ambitious decarbonisation targets and advanced electricity market structures to the same extent.
Ireland’s DS3 programme has already demonstrated how system operators can procure services required to operate grids with exceptionally high levels of non-synchronous generation. The United Kingdom has developed increasingly sophisticated markets for dynamic frequency response and stability services. Spain is integrating advanced inverter capabilities into future network planning.
Across continental Europe, transmission system operators are investing in synchronous condensers, reactive power compensation and advanced control technologies.
Individually, these developments appear incremental. Collectively, they reveal a common direction of travel: Europe is constructing the foundations of what could become a grid stability economy.
The objective is no longer merely to procure energy. It is to procure the conditions that allow energy markets to function.
That distinction may become one of the defining features of the next phase of the energy transition.
North America’s Reliability Challenge
North America is approaching the issue from a different starting point.
The United States and Canada still retain significant fleets of dispatchable synchronous generation. As a result, concerns around inertia and system strength have emerged more gradually than in Europe.
Nevertheless, the underlying dynamics are converging.
Rapid growth in solar and battery storage deployment is changing system behaviour across markets such as Texas, California and the American Southwest. At the same time, electrification, industrial reshoring and the expansion of artificial intelligence infrastructure are driving unprecedented growth in electricity demand.
The challenge is no longer simply generating enough power. It is ensuring that power systems remain stable under increasingly complex operating conditions.
Regional transmission organisations are therefore paying growing attention to inverter-based resource integration, advanced reliability services and future ancillary-service design.
North America may not yet have its equivalent of Germany’s Momentanreserve. However, the economic logic underpinning such mechanisms is becoming increasingly difficult to ignore.
China’s Grid Stability Build-Out
China is pursuing the same objective through a different model.
Where Europe often leads market innovation and North America focuses on reliability planning, China excels at deployment.
The country has become the world’s largest market for battery storage, advanced power electronics and transmission infrastructure. Increasingly, these investments are focused not only on renewable generation but also on system stability.
Large-scale grid-forming battery projects, hybrid renewable-storage systems and advanced transmission technologies are being deployed at a pace unmatched elsewhere.
China appears to have reached a strategic conclusion: the next stage of the energy transition will not be won by generating renewable electricity alone, but by operating renewable electricity systems reliably.
That distinction is becoming increasingly important as nations compete on industrial competitiveness, energy security and system resilience.
The Investment Implications Are Enormous
Investors often describe battery storage as one of the defining infrastructure opportunities of the coming decade.
They may be underestimating the scale of the opportunity.
The larger investment theme may not be storage itself but the wider ecosystem required to support grid stability.
Grid-forming batteries, synchronous condensers, long-duration energy storage, reactive power compensation systems, advanced power electronics, digital control platforms and grid-enhancing technologies all stand to benefit from the same structural trend.
If inertia, system strength and voltage support become explicitly valued, a new infrastructure category emerges.
Importantly, much of this investment is not optional. It becomes necessary simply to maintain system operability as renewable penetration rises.
This creates characteristics infrastructure capital typically favours: essential-system status, long asset lives, predictable demand and high barriers to entry.
The first trillion dollars of the energy transition built renewable generation. The next trillion dollars may build renewable stability.
How Large Could the Grid Stability Economy Become?
One of the reasons stability services remain underappreciated is that they are not easily visible in traditional energy statistics.
Yet system operators across Europe, North America and Asia are already investing materially in maintaining stability in increasingly inverter-dominated systems.
Transmission system operators are deploying synchronous condensers, reactive power compensation systems, digital control infrastructure and grid-enhancing technologies at scale. These investments are rarely labelled as “stability spending”, but they perform exactly that function.
Across Europe alone, the transition to a highly renewable system is expected to require hundreds of billions of euros of energy-system investment through the 2030s. While most attention focuses on generation and transmission expansion, a growing share of this capital will inevitably be directed towards ensuring system operability under low-inertia conditions.
Battery energy storage systems illustrate the scale effect. As grid-forming capability becomes more widely required, even modest cost uplifts per project translate into significant aggregate investment across hundreds of gigawatts of deployment.
Taken together, the emerging grid stability economy is unlikely to be a single market. It is more plausibly a distributed infrastructure layer spanning multiple technologies and system functions.
Its total scale is uncertain, but it is already large enough to influence industrial strategy and infrastructure capital allocation.
More importantly, it represents a shift in what is being financed.
For decades, investors financed the production of electricity. Increasingly, they are beginning to finance the conditions that make electricity systems work.
The Challenges Facing the Grid Stability Economy
Yet the emergence of a grid stability economy is far from inevitable.
One challenge is that nobody yet knows how much inertia is actually worth. Unlike electricity, inertia is not consumed. Systems simply require sufficient quantities to remain stable, which makes pricing inherently more complex than traditional energy markets.
There is also a possibility that stability services become essential without becoming particularly lucrative. Revenue pools may ultimately prove smaller than many developers and investors currently assume.
Europe faces an additional challenge: fragmentation. Divergent national approaches to inertia procurement, system strength requirements and grid-forming standards risk creating a complex patchwork of rules that could slow investment and increase uncertainty.
The technology itself presents further uncertainty. While grid-forming systems are advancing rapidly, many associated revenue streams remain immature. Banks finance predictable cash flows, not technical potential, and until markets mature, caution is likely to remain.
There is also a deeper structural risk that the industry may be focusing on the wrong constraint. Future bottlenecks could emerge in transmission, distribution networks, demand flexibility or industrial electrification rather than inertia itself.
Finally, policymakers may decide that certain stability services are too important to be left entirely to competitive markets. In that case, inertia, voltage support and system strength could be procured through regulated mechanisms rather than market-based frameworks.
The Grid Stability Economy may still emerge, but its structure may look very different depending on these choices.
The Future Bankability Question
This uncertainty raises a central question for investors.
Future valuation of power assets may depend less on traditional variables such as resource quality and energy prices, and more on the ability of those assets to provide system stability services.
Can the asset provide grid-forming functionality? Can it participate in stability-service procurement? Can it remain compliant with evolving grid codes? Can it access multiple revenue streams linked to reliability and system performance?
Two futures are possible.
In one, competitive markets for inertia, system strength and voltage support emerge across major economies. In the other, these services become regulated infrastructure functions delivered through transmission-system operators.
Both scenarios support investment, but they distribute risk differently.
The critical point is that stability itself is becoming economically visible.
Conclusion: Pricing Physics
Germany’s inertia market may ultimately be remembered not because it procured inertia, but because it marked the moment electricity markets began confronting a reality they had long ignored.
The physical foundations of power systems have economic value.
For decades, those foundations were supplied implicitly by conventional generation. As the energy transition accelerates, they must increasingly be supplied explicitly.
Whether future stability services are traded through competitive markets, procured by system operators or embedded within grid-code requirements remains uncertain.
What appears increasingly clear is that the next phase of the energy transition will not be defined by the production of renewable electricity, but by the challenge of preserving stability in power systems dominated by power electronics.
Germany’s inertia market may one day be viewed as a technical footnote. Or it may be remembered as the moment electricity markets began assigning a price to physics.
If that process continues, the coming decade will not simply be about building more renewable generation. It will be about constructing an entirely new layer of infrastructure dedicated to ensuring that highly renewable power systems remain stable, operable and investable at scale.
The first phase of the energy transition transformed how electricity is produced.
The second phase will determine whether it can be reliably used.
Author: Derek Michalski, Editor
