A Brief Overview of the Principle of Energy Solidarity in EU law and Its Interplay with Divergent National Strategies of Member States

Table of contents: 1. Introduction. – 2. The meaning of the principle of energy solidarity and its emergence as a legally binding principle. – 2.1. Definition of the principle of energy solidarity. – 2.2. The Opal Case: The emergence of energy solidarity as a fundamental legal principle. – 3. The principle of energy solidarity in interplay with divergent national strategies of EU member states. – 3.1. National energy strategies contravening the principle of energy solidarity. – 3.2. Energy solidarity in relation to the sovereignty of member states to determine their energy sources and the general structure of their energy supply. – 4. Final remarks.

Abstract: The principle of energy solidarity has the feature of promoting two poles that may seem opposed: on the one hand, the proper functioning of the single market, and on the other, the guarantee of access to energy for all, besides its political dimension, has emerged from the CJEU case-law as a principle with legally binding effect. National governments are therefore bound to consider the interests of fellow member states in the exercise of their energy policies. At the same time a reasonable balance of different member states’ possibly conflicting interests and the isolation of free-rider phenomena are expected from the EU institutions in the adoption of energy measures. The member states’ sovereign right to determine their energy mix is certainly not abrogated but exercised in compliance with the principle of energy solidarity. The strengthening of the EU and its progressive affirmation as a hard power are among the most efficient paths to energy security.

Keywords: energy solidarity – legal binding principle – security of supply – efficiency – energy sovereignty – proportionality.

1.   Introduction

The principle of solidarity is unquestionably the angular stone of the European Union. Inserted in several provisions of EU primary law, it serves the purpose of guaranteeing political, social, economic independence and integrity of the Union. As aptly pointed out by the former President of the European Commission, Jean-Claude Juncker: 

‘Solidarity is the glue that keeps our Union together. The word solidarity appears 16 times in the Treaties which all our Member States agreed and ratified. Our European budget is living proof of financial solidarity. […] The euro is an expression of solidarity. Our development policy is a strong external sign of solidarity. And when it comes to managing the refugee crisis, we have started to see solidarity. I am convinced much more solidarity is needed. […] When the Portuguese hills were burning, Italian planes doused the flames. When floods cut off the power in Romania, Swedish generators turned the lights back on. When thousands of refugees arrived on Greek shores, Slovakian tents provided shelter’.[1]

Specific reference must be made to Articles 2 and 4 TEU,[2] where solidarity is placed at the heart of the core values of the EU. Nevertheless, there is no clear definition of its nature in any of the treaty provisions. Primary law does not actually clarify whether solidarity is a fundamental principle or a constitutional value or even an obligation for member states.[3] The same goes for the energy field where the relevant treaty provisions (Articles 122 paragraph 1 and 194 paragraph 1 of the TFEU) do not explicitly precise neither the nature nor the scope of the principle. The issue is of utmost importance, as energy is an essential element for the functioning and survival of any society, as well as a fundamental component of civilisation. The topic is, furthermore, particularly timely as, since the Russian invasion in Ukraine, Europe has experienced one of the deepest energy crises in its history. Relations with Russia remain far from being restored, while the United States clearly shows signs of isolationism and, in any case, of distancing itself from the European Union. The international landscape is challenging with fluctuations in oil and gas prices and at the same time there is a significant need for green transition. The EU Member States have no choice but to remain united and act in solidarity in the field of energy, even if, in certain cases, they are called upon to revisit concepts such as national sovereignty and make concessions in parts of their national strategies.

The first part of the present article examines the nature of the principle of energy solidarity, in its political and legal dimension. It analyses its relationship with the objectives set out in Article 194(1) TFEU in the field of energy, as well as its role in times of crisis.The approach is developed through an examination of key elements of EU legislation as well as the case law of the Court of Justice of the European Union (CJEU). The second part of the Article refers to the different national strategies of the Member States in the field of the energy mix and to the different objectives pursued by them. It demonstrates the interplay of the principle of energy solidarity with the above divergences by exposing the different approaches and risks’ assessments and their impact on the intestate relationships within the EU. The Article seeks to shed light on the impasses that can emerge during periods of crisis as a direct result of these divergences. The analysis ultimately argues for the close link of the principle of energy solidarity to the energy security as well as for the need to reconcile energy sovereignty with energy solidarity within the EU’s legal and political framework. 

2.   The meaning of the principle of energy solidarity and its emergence as a legally binding principle

2.1.  Definition of the principle of energy solidarity

The Treaty of Lisbon established two legal bases of the principle of solidarity in the energy field, namely Articles 194(1) and 122(1) TFEU. The first paragraph of Article 194 sets four objectives related to the EU energy policy evoking a spirit of solidarity between member states;[4]

1. Security of energy supply, 
2. Functioning of the energy market, 
3. Energy efficiency and energy saving and the development of new and renewable forms of energy and 
4. The interconnection of energy networks. Member states should coordinate their efforts and their actions to ensure the achievement of the above-mentioned objectives driven by a solidarity spirit. 

Hence, both EU policies and national policies are affected and the principle of solidarity has both horizontal and vertical effect. First paragraph of Article 194 as complemented by its second paragraph may be used as the ‘general basis for all energy policy measures’ taken by the EU institutions.[5]

The role of solidarity is particularly important in terms of security of energy supply but also of promotion of the interconnection of different energy networks and mostly electricity networks. The latter is illustrating the interdependency of member states and therefore the need for a strong solidarity guaranteeing the well-functioning of the infrastructures. Security of energy supply, as K. Talus and P. Aalto suggest, is associated with ‘constant availability of affordable energy with minimal social costs, including environmental costs’.[6] Solidarity comes to correct the internal market’s failures and fill in the gaps of free competition in the field of supply.[7] The liberalized single market, despite its positive impact on the supply potential of different member states, has neither always succeeded in guaranteeing better prices for the consumers[8] nor ensured energy independence for member states.[9] The two poles, namely free competition and energy solidarity, do not necessarily meet. As pertinently pointed out, ‘competition and solidarity are only distant cousins’.[10] Nevertheless, they can complete each other. Mechanisms of energy solidarity between member states can compensate for the market’s failures by activating inter-state aid but also social policy measures on the national level.[11]

During the energy crisis in Europe in 2022-2023 market mechanisms were proved insufficient and not willing to ensure that gas would flow to regions where it was needed most. Countries in central and eastern Europe faced considerable gas shortages whereas countries like Spain could resist shock. For example, member states like Czech Republic, Slovakia, Hungary or Slovenia had no access to LNG terminals. Providing assistance to partner EU countries is not something the market automatically guarantees on its own. Besides, it is impossible for it to resolve problems related to physical constraints in the short term. Furthermore, market and competition might encourage energy suppliers to withhold gas until prices rise, thereby reducing available supply and increasing inequities among consumers in different countries. Moreover, in the context of a liberalized market the negotiating power of individual states varies significantly, as wealthier countries are better positioned to secure alternative suppliers. So consumers in less advantaged countries may be more exposed to energy shortages. 

The link of security of supply to solidarity should be stronger in a context of continuous political instability outside the external borders of EU. Several member states have run the risk of deprivation of sufficient supply. Not only the continuous frictions between Russia and Ukraine, already mentioned earlier and culminating in the Russian invasion, but also the ongoing tensions in the Middle East and the political instability in Libya are also compelling examples. Besides, the very origin of the first paragraph of Article 194 bears witness to this kind of political worries of certain member states. More specifically, Poland insisted on the need to make reference to the ‘spirit of solidarity’ in the provision of the first paragraph.[12] It is also one of the reasons leading to its inclusion in the five dimensions of what is commonly called the Union of Energy.[13] In its Communication of 25 February 2015,[14] the EU Commission devises a strategy with five mutually-reinforcing and closely interrelated dimensions among which solidarity is found. The vision is clearly described: ‘an Energy Union where Member States see that they depend on each other to deliver secure energy to their citizens, based on true solidarity and trust, and of an Energy Union that speaks with one voice in global affairs’.[15]

Solidarity is not only understood as a principle guiding the relationship between member states but also guiding the public governance within member states. On the national level, market mechanisms do not necessarily guarantee affordable prices for the most vulnerable consumers. Free competition in liberalized markets would never take into consideration the differences between several categories of consumers in terms of economic resources. Energy access to all consumers is clearly not a market goal. Moreover, within a country there may be regional disparities as the commercial value of all areas is not the same. Industrial zones or heavily touristed areas are more likely to attract investments than regions with limited commercial potential, which can lead to less affordable energy prices for the residents of the latter. So the public sector is called to intervene and correct the above failures. Therefore, the principle of solidarity reflects the nature of energy as a public service. Moreover, the Charter of Fundamental Rights itself regards services of general interest as an expression of the principle of solidarity.[16]

As aptly pointed out energy supply ‘is part of the essential quality services to which all individuals are entitled’.[17] According to CJEU case-law, energy supply is considered a service of general economic interest falling in the scope of the second paragraph of Article 106 TFEU. For instance, in case Anode[18] the Court assessed that Member States are allowed to impose public service obligations such as regulated tariffs for certain customers on electricity suppliers, in order to guarantee objectives like security of supply, consumer protection, affordability, and continuity of the service. However, the Court stated that such measures must comply with the principles of necessity and proportionality, meaning they must be limited in time, clearly defined, and no broader than necessary to achieve those public interest objectives.[19]

Although there is no solemn recognition of a ‘right to energy’ in EU hard law, there are implicit references to this right. Illustratively, Article 27 of the Directive 2019/944[20] affirms in its second paragraph that member States ‘shall take appropriate measures, such as providing benefits by means of their social security systems to ensure the necessary supply to vulnerable customers, or providing for support for energy efficiency improvements, to address energy poverty where identified’. Furthermore, in principle 20 of the European pillar of social rights energy is explicitly mentioned as an essential service alongside water, transport and others. More specifically, it is stated that ‘Everyone has the right to access essential services of good quality, including water, sanitation, energy, transport, financial services and digital communications. Support for access to such services shall be available for those in need’.[21] Despite the soft law character of the latter,[22] its importance is not questioned as it reflects the political will of member states to envisage energy as a public good.

Therefore, the EU, in an effort to address market’s failures, had already adopted, inter alia, Regulation 2017/1938[23] on the basis of Article 194 TFEU. Article 13 of the said Regulation is a clear example of solidarity between member states as it legally obliges them to supply gas to neighbouring partner countries in critical need and particularly to vulnerable consumers, such as healthcare providers and households. However, the provision of a compensation clause for the state providing solidarity raises questions regarding the very concept of solidarity, which traditionally is not associated with the characteristics of an onerous contract. Nevertheless, the importance of this provision remains significant within the EU framework. 

Additionally, Article 15(a) of the directive EU 2024 /1711[24] enacts the right of households, small enterprises, medium-sized enterprises, public bodies and other categories of final customer to energy sharing within the same bidding zone or a more limited geographical area, as determined by member states (paragraph 1). It further provides that appropriate and non-discriminatory measures shall be taken to ensure that vulnerable customers and customers affected by energy poverty can access energy sharing schemes. Those measures may include financial support measures or production allocation quota. Consequently, energy sharing projects owned by public authorities make the shared electricity accessible to vulnerable or energy poor customers or citizens. When doing so, Member States shall do their utmost to promote that the amount of that accessible energy is at least 10% on average of the energy shared (paragraphs 7, 8). 

Despite the importance of both the guiding provisions of Article 194 TFEU and the secondary legislation based on them in addressing the shortcomings of the free market through mechanisms of energy solidarity, the legal basis provided by Article 122(1) TFEU has proved a valuable asset in times of crisis.[25] The latter is considered lex specialis in relation to Article 194, in the sense that it applies only in a context where severe difficulties arise.[26] Although it also evokes the spirit of solidarity, its importance seems to be less of political nature compared with the precited Article 194(1) TFEU. As pertinently pointed out this Article ‘provides a spirit of solidarity in any action relating to EU policy in the energy field’.[27] More solidarity initiatives on the legal and political level were demanded when Russia weaponized energy since the invasion in Ukraine. This is where Article 122(1) TFEU intervenes and serves as a legal basis for supplementary measures to deal with crisis. 

Accordingly, a number of regulations were enacted pursuant to the above Article. An indicative reference is made to a few important legal texts. Council Regulation (EU) 2022/1369[28] aimed, by Article 3, at the reduction of gas consumption of member states at least by 15%. Furthermore, Council Regulation (EU) 2022/1854[29] ‘establishes an emergency intervention to mitigate the effects of high energy prices through exceptional, targeted and time-limited measures’ (Article 1). Articles 6 and 7 of the said regulation provide measures to address high energy prices by setting a revenue cap (€180 per megawatt-hour) for low-cost producers, namely those that produce electricity at a lower cost than the market's marginal price. Subsequently, Council regulation 2022 /2576[30] establishes in Articles 6, 7 and 8 a centralized mechanism to aggregate gas demand and collectively negotiate with suppliers in the EU. Joint purchasing of gas including the aggregation of demand and the allocation of gas volumes across the Union is provided. This can allow smaller countries to access gas more affordably, as part of an effort to correct market failures arising from unequal negotiating power.

Interestingly, energy solidarity is not only connected to security of supply but also, among others, to the functioning of the energy market itself taking primarily into account the interconnection of the electricity networks of different member states. The second paragraph of Article 74 of the Commission Regulation (EU) 2015/1222[31] provides that ‘[t]he redispatching and countertrading cost sharing methodology shall include cost-sharing solutions for actions of cross-border relevance’. This provision is interpreted in accordance with Article 16(13) of the Regulation 2019/943[32] requiring that the costs of the remedial actions activated by the Transmission System Operators (TSOs) in order to ensure cross-zonal trade are to be shared between the TSOs according to the extent to which flows resulting from transactions internal to zones contribute to the congestion between two zones observed. 

BnetzA[33] judgement of the General Court is an enlightening example as it concerns the cost allocation methodology for cross-border congestion management measures with regard to dispatching and countertrading in the CORE region, comprising Belgium, the Czech Republic, Germany, France, Croatia, Luxembourg, Hungary, the Netherlands, Austria, Poland, Romania, Slovenia and Slovakia. The applicant BnetzA, National Regulatory Authority in Germany, seeked the annulment of a decision of the Board of Appeal of the European Union Agency for the Cooperation of Energy Regulators (ACER) of 30 November 2020 on the proposal of the electricity transmission system operators (‘TSOs’) of the ‘Core’ capacity calculation region. According to the contested cost-sharing methodology cross-border relevant network elements are all critical network elements as well as internal network elements with a voltage level higher than or equal to 220 kV.[34] The contested decision defined cross-border relevant redispatching and countertrading actions as all such actions intended to relieve congestion on cross-border relevant network elements.[35] The applicant claimed, though, that the costs of the remedial actions attributed to internal network elements that are not interconnectors or, at most, critical network elements should be excluded from cost sharing.[36]

The Court held that cross-border relevant remedial actions are all those that are at least sometimes able to address violations of current limits on cross-border relevant network elements, that is to say, in principle, all critical network elements taken into account for the calculation of cross-zonal capacity, and all other network elements with a voltage level higher than or equal to 220 kV.[37] It even added that when remedial actions activated by a TSO on internal elements that are not critical network elements form part of the optimal solution necessary to relieve congestion on critical network elements as well, the costs relating to the former elements must be shared between the TSOs in the same way as those relating to the latter.[38] Therefore, the Court rules that flows resulting from internal transactions that contribute to the congestion between two bidding zones observed, described in Article 16(13) of Regulation 2019/943, which reduce cross-zonal capacity on critical network elements, cannot be treated differently, in cost sharing, where those flows pass through non-critical network elements.[39]

Nevertheless, it reserved the possibility for a TSO to establish that a non-critical network element with a voltage level higher than or equal to 220 kV can never be useful for ensuring regional security and guaranteeing the firmness of allocated cross-zonal capacity and therefore exclude it from the sharing of costs.[40] Furthermore, given that loop flows are the only situation in which costs relating to non-critical network elements are shared and the primary contributor to congestion subject cost sharing, the Court assessed that a TSO cannot be exempted from the costs that it causes to the other TSOs on the non-critical elements of their networks with its loop flows that exceed the threshold, even if the remedial actions on those elements contribute to ensuring cross-zonal trade.[41] Thus, it dismissed the above mentioned claim of the applicant.

In its reasoning the Court explicitly connected the above assessment to the principle of energy solidarity stating that the cost exemption demanded by the applicant would ‘be contrary to the principle of energy solidarity, as interpreted by the Court of Justice’.[42] Mutual responsibility is prioritized with TSOs sharing costs when their actions entail burdens on others. The General Court upholds the same position in the TenneT TSO[43] case where it also dismissed the applicants’ claim for exemption from the costs that they cause to the other TSOs on the non-critical elements of their networks with their loop flows that exceed the threshold, even if the remedial actions on those elements contribute to ensuring cross-zonal trade.[44] The Court stressed that ‘it would be contrary to the principle of energy solidarity to allow TSOs that cause loop flows that pass through other bidding zones to avoid the costs of remedial actions that have been activated in the common interest in order to optimise cross-zonal capacity, while at the same time ensuring network security as efficiently as possible, to the benefit of all TSOs and, accordingly, electricity consumers’.[45] Under these circumstances, solidarity appears as a mechanism that supports both the proper functioning of the internal electricity market and the interests of the consumers. 

The doctrine also qualifies the relationship between the principle of energy solidarity and the functioning of the internal market as circular. Solidarity derives from the objectives of internal market embracing both member states and private actors but at the same time it works as a remedy to its failures.[46] For example, how could member states respond efficiently to eventual generalized blackouts resulting from decisions taken by authorities of other member states given the interconnection of networks?[47]Interconnections play a key role in securing the supply. In cases of natural disasters, technical failures or geopolitical crises, they also allow for a faster restoration of electricity supply. Apart from being a valuable tool of the internal energy market, they are also an expression of solidarity among member-states.[48] As the EU Commissioner Jørgensen noted ‘Member States can import from their neighbours when needed, or provide backup supplies to help and prevent blackouts’.[49] On the other hand, the interconnections may cause imbalances in national electricity systems, especially when the needs of the countries differ significantly. Countries that import more electricity usually end up paying more, because it is their consumers who benefit from getting access to the cheaper power produced abroad.[50] Besides, poor coordination or a failed implementation of European legislation on cost sharing may create problems in the electricity grids of member states.

The recent example of the blackout in Spain on 28 April 2025 is highly illustrative. It impacted the entire Iberian Peninsula. During that period the share of inverter-based renewable energies in the energy mix increased compared to conventional technologies, making the Iberian electric grid more vulnerable to potential disruptions and therefore requiring stronger support from neighboring systems.[51] According to Spanish and Portuguese administrations, interconnections account for just 3% of the peninsula’s generation capacity.[52] Therefore, the question is raised: what would have happened if the interconnection capacities had been greater?[53] Furthermore, different culprits were pointed out shortly after the incident happened. The report commissioned by the Spanish government identified as culprits a) the system operator (Red Eléctrica de España), which allegedly misjudged reserve capacity requirements for the day of April 28 (an accusation rejected by Red Eléctrica in a report dated June 18), and b) the generation companies, which failed to correct the surge that appeared on the network as they should have (they obviously passed the blame on to Red Eléctrica).[54] The expert panel of the ENTSO-E, during its ongoing investigation on the incident, is considering two lines: enhancing voltage control management procedures and capabilities of all active actors of the electricity system to prevent such major voltage-related incidents in the future and assessing how the system defense plans can better protect the European power system against this new type of phenomena.

According to K. Huhta and L. Reins ‘[t]he increased interdependence due to shared resources necessitates mutual trust, solidarity and faith across Member States that the operation of the internal market will lead to energy resources being available to buy and sell so as to fulfil demand and ensure energy security across EU Member States’.[55] Still, of course, as correctly observed, free competition remains the reference model within the EU guiding the relations between member states. Solidarity mainly expressed by interventions of the public sector in different member states keeps a subsidiary role.[56] Article 194 TFEU calls both member states and the EU to cooperate and coordinate their actions. The Commission is entitled to stand by the member states during their negotiations concerning the long-term energy supply respecting though the energy mix that they have chosen on their national level and the principle of subsidiarity.[57] Nevertheless, the wording of the provision (spirit of solidarity) along with the subordination of the action of EU institutions to national policies leads to the conclusion of a limited judicial impact of the principle of energy solidarity.[58] The provisions of Article 194TFEU used to be considered more of a declaration of political intentions than a legally binding Article.[59]

As inferred from the EU primary and secondary law, solidarity has a double dimension namely as a tool of long term policy and planning but also as a means of dealing in a very short term with severe energy crises. Nevertheless, the very essence of the principle remains the same under both of the above perspectives. It is linked, in both its forms, to safeguarding the proper functioning of the energy market, energy security, and the energy supply for all consumers in the EU, during both normal conditions and times of crisis.

2.2.  The Opal case: the emergence of energy solidarity as a fundamental legal principle 

Although solidarity penetrates the entire EU strategy in the energy field and has various practical applications particularly in the scope of Article 122(1) TFEU, still EU legislation does not clearly define it as a legally binding principle, but it rather links it with a political will that should be demonstrated by member states. The CJEU changes the landscape with its audacious Opal judgment. The OPAL gas pipeline is the terrestrial section, to the west, of the Nord Stream 1 gas pipeline, the point of entry to which is located close to the area of Lubmin, near Greifswald, in Germany, and the point of exit from which is in Brandov in the Czech Republic. The pipeline is owned by WIGA Transport Beteiligungs-GmbH & Co. WIGA is jointly controlled by OAO Gazprom and BASF SE. In June 2009 the Commission asked the German national regulatory authority (BNetzA) to ensure that dominant energy undertakings, such as Gazprom, were not allowed to reserve, in a single year, more than 50% of the transport capacities of the OPAL pipeline at the Czech border unless certain guarantees were given. 

On 12 April 2013 OGT, OAO Gazprom and Gazprom Eksport LLC formally requested the BNetzA to vary certain provisions of the exemption granted in 2009. On 13 May 2016, the BNetzA notified the Commission, on the basis of Article 36 of Directive 2009/73,[60] of its intention, following the request submitted by OGT, OAO Gazprom and Gazprom Eksport, to vary certain provisions of the exemption granted in 2009 regarding the share of the OPAL pipeline operated by OGT by concluding with the latter a public law contract, which, under German law, is equivalent to an administrative decision. On 28 October 2016, the Commission adopted, on the basis of Article 36(9) of Directive 2009/73, Decision C(2016) 6950[61] on the OPAL pipeline exemption under Directive 2003/55. 

As a result, the German regulator authorized Gazprom to use up to 80% of the pipeline’s capacity and even its full capacity if there was no third-party demand. Poland brought an action against the above-mentioned Commission decision before the General Court demanding its annulment and claiming, inter alia, that there had been a violation of the principle of energy solidarity as it is established by Article 194 TFEU. The contested decision was threatening Poland’ status as a gas transit country by authorizing the full use of Opal pipeline’s capacities. Gas transport to Europe by the Ukrainian and Polish corridors provided both a revenue and a negotiating power to those countries.[62] According to the Republic of Poland, measures adopted by EU institutions that compromise the energy security of certain regions or in certain Member States, including their security of gas supply, would be contrary to the principle of energy solidarity.

More specifically, the Polish state alleged, inter alia,[63] that the lack of significant growth in demand for natural gas in central Europe would have an influence on the conditions of supply and use of transmission services of the pipelines competing with OPAL, namely the Braterstwo and Yamal pipelines, in the form of a reduction or even a complete interruption of the transmission of gas through those two pipelines. Such a limitation or interruption in transmission through the Braterstwo pipeline would have the effect of rendering impossible the maintenance of supply on the territory of Poland through the pipeline from the Ukraine, which would result in it being impossible to guarantee the continuity of supply for clients on the territory of Poland. Accord to its claims, the Commission failed to examine the consequences of such an eventuality and more precisely the impossibility, for the companies responsible for it, of meeting their obligation to guarantee the supply of gas to protected clients, the impossibility of the gas system functioning effectively and of assigning commercial operating opportunities for gas storage facilities and the likelihood of a considerable increase in the cost of obtaining gas. 

In this context, the General Court stated that the ‘spirit of solidarity’ referred to in Article 194(1) TFEU is the specific expression in this field of the general principle of solidarity between the Member States, mentioned, inter alia, in Article 2 TEU, in Article 3(3) TEU, Article 24(2) and (3) TEU, Article 122(1) TFEU and Article 222 TFEU.[64] Its content entails rights and obligations both for the European Union and for the Member States. On the one hand, the European Union is bound by an obligation of solidarity towards the Member States and, on the other hand, the Member States are bound by an obligation of solidarity between themselves and with regard to the common interest of the European Union and the policies pursued by it.[65] It is also important to emphasize on the General Court’s remark that in the context of energy policy the principle of energy solidarity cannot be restricted to extraordinary situations which would exclusively involve the competence of the EU legislature, but it also entails a general obligation on the part of the European Union and the Member States, in the exercise of their respective competences, to take into account the interests of the other stakeholders. The General Court sets, nonetheless, limits to the principle of solidarity by ruling that its application does not mean that EU energy policy must never, under any circumstances, have negative impacts for the interests of a Member State in the field of energy. However, the EU institutions and the Member States are obliged to consider, in the context of the implementation of that policy, the interests of both the European Union and the various Member States and to balance those interests where there is a conflict.[66] After considering the circumstances of the case, the General Court concluded that the contested decision of the EU Commission was adopted in breach of the principle of energy solidarity, as provided for in Article 194(1) TFEU.

An appeal against the judgement of the General Court was brought before the CJEU by the Federal Republic of Germany on the grounds of the incorrect legal assessment and the non-applicability of the principle of energy solidarity. The Court upheld the contested judgment by stating, inter alia, that the EU institutions and the Member States must take into account the interests of all stakeholders liable to be affected, by avoiding the adoption of measures that might affect their interests, as regards security of supply, its economic and political viability and the diversification of sources of supply, and to do so in order to take account of their interdependence and de facto solidarity.[67] According to the reasoning of the CJEU, the principle of energy solidarity, referred to in Article 194 TFEU, should be considered in the context of the establishment and functioning of the internal market and, in particular, the internal market in natural gas, by ensuring security of energy supply in the European Union, which means not only dealing with emergencies when they arise, but also adopting measures to prevent crisis situations. To that end, it is necessary to assess whether there are risks for the energy interests of the Member States and the European Union, and in particular to security of energy supply.[68] It is also important that the CJEU upheld the same limits set by the General Court in the sense that the application of the principle of energy solidarity does not mean that EU energy policy must never, under any circumstances, have negative impacts for the particular interests of a Member State in that field and a balance of interests liable to be affected should take place.[69]

On the political level the importance of the Opal judgment is unquestionably admitted. The Court made clear its discordance with the Commission who seemed hesitant about eliminating or at least reducing energy dependency on Russian gas despite the previous invasion of the Crimean Peninsula in 2014.[70] As for the importance of the judgment on the legal level, the CJEU judgment establishes, beyond any doubt, energy solidarity as a legally binding principle and even further a founding principle of the energy Union with both horizontal and vertical dimension.[71] The Court’s reasoning confirms a double ‘nature’ of solidarity, calling both for preventing measures and emergency actions to deal with crises. This is also a definite answer to a long debate on the content of the principle emanating mainly from the secondary law which used to connect it to situations of crises, namely energy shocks.

 Furthermore, as it results from the CJEU judgment, energy solidarity, as a primary law principle, is to be applied directly by both the administrative authorities and the Courts in the context of decision making and judicial review respectively.[72] A balance of conflicting energy interests involved is required every time a decision is likely to have an impact on the energy security of one or more member states or the EU. The burden of the analysis, as already mentioned, does not only lie with the EU institutions but also with national authorities. It is an important step to the consolidation of a real energy community where member states do not only act according to their energy backgrounds and their national priorities but also as part of the supranational system of the EU. 

Despite the positive impact of the judgement mostly by putting an end to long term doubts on the scope and the legal validity of the principle, several concerns arise from its reasoning. There is no further clarification on the specific criteria of the so-called solidarity test.[73] How exactly the conflicting interests will be balanced? What should the involved authorities emphasize on? What is the exact meaning of security of supply and what would be the minimum beyond which there is a threat to the security of supply of a member state? The practical application of the principle remains complicated even after the CJEU judgment.[74] Far from being the panacea to the problem, the judgment risks to lead to a situation where any member state, considering itself to be damaged by a decision of the EU or a fellow member state in the energy field, could initiate legal proceedings on the grounds of breach of energy solidarity.[75] Following this path member states might have an ‘excuse’ to intervene in the planning and development of new energy infrastructures and abusive proceedings could not be excluded.[76]

The Advocate General connected the principle not only to the energy supply but also to the entire set of the objectives fixed by Article 194(1) TFEU,[77] reinforcing what already arises from the Treaty. However, no clear or specific criteria are fixed for the application of the principle in the sectors of energy efficiency and energy saving and the development of new and renewable forms of energy. As very appropriately questioned, ‘does the principle of solidarity now require that countries must restrict increases in renewable energy based power generation on account of its potentially negative effects on neighbouring states?’.[78] Therefore, in the light of the principle of energy solidarity, the notion of energy security risks to turn into an indeterminate legal concept threatening the legal certainty,[79] that is to say a substantive element of the rule of law in both the EU and the national legal orders. Besides, as will be mentioned below, legal certainty is at stake not only due to a lack of precision in the criteria of balancing the conflicting interests involved but also to an apparent contrast between on the one hand the principle of energy solidarity and on the other hand the principles of attributed power of the EU and energy sovereignty of its member states.

3.   The principle of energy solidarity in interplay with divergent national strategies of EU member states

3.1.  National energy strategies contravening the principle of energy solidarity

Despite the liberalization of the single energy market, national energy policies have remained distinct over a long time. Factors like the insufficient interconnection of energy transport networks and the fragmented European energy market are mostly ‘technical’ obstacles to a successful harmonization of national energy strategies. The different situations of EU member states justify or at least explain their different approaches. Political forces and political trends within countries, existing natural resources, taxation policies have a very strong influence on national choices. Case Republic of Austria v Commission[80] is an example of the frictions between Member States stemming from their different political starting points. In the above case the Republic of Austria asked, by an action based on Article 263 TFEU, for the annulment of the Regulation (EU) 2021/2139[81] that established the technical screening criteria to include certain activities in the nuclear energy and fossil gas sectors in the category of activities deemed to contribute substantially to climate change mitigation on the basis of Article 10(3) of the Taxonomy Regulation,[82] and in the category of activities deemed to contribute substantially to climate change adaptation on the basis of Article 11(3) of that regulation.

According to the applicant’s allegations, the Commission did not conduct required consultations or impact assessments and did not properly assess compatibility with climate law. Inclusion of nuclear energy and gas involves ‘essential elements’ which should have been decided by the legislature.[83] Furthermore, nuclear energy and gas might cause significant harm to environmental objectives, such as risks from radioactive waste, reactor accidents and life-cycle emissions) and the technical screening criteria did not rule these out.[84] Besides, allegedly, there can be low-carbon alternatives, including renewable energy, which could become technologically and economically feasible, so that the disputed inclusion of gas/nuclear under sustainable is unjustified.[85] The applicants argued, therefore, in favor of the violation of precautionary principle as the Commission did not base its decision on conclusive scientific evidence.[86]

The General Court, in its grand Chamber, dismissed the action of the Austrian Republic holding that the Commission acted within its delegated powers under the Taxonomy Regulation and stating, inter alia, that the criteria in question rule out the possibility of significant harm under the environmental objectives with sufficient certainty.[87] Pursuant to the Court’s reasoning the Commission provided enough justification, used available scientific evidence, and respected the precautionary principle insofar as EU law requires.[88] The Court also found that Austria failed to demonstrate that low-carbon alternatives exist and that they are feasible to meat continuity and reliability of supply. According to the Court’s final conclusion, the Regulation in question is lawful. 

The cases of four EU member states, namely Germany, France, Poland and Hungary, also illustrate the divergence in their approaches. Germany was opposed to the development of nuclear power and the construction and commissioning of nuclear power plants. The Fukushima accident in Japan in 2011 did accelerate the process of shutting down progressively the nuclear power plants. The country’s strategy on that matter is in contrast with the respective pronuclear strategy of France, the second powerful pole in the EU. The green taxonomy has been a field of confrontations. As has been said 

‘The question of classification of nuclear and gas as green energies is not just a technical debate. What is really at stake here has less to do with a controversy over risk management, waste storage or air pollution than with the defense of national interests of EU member states, with France and Germany being at the forefront. The compromise that will be found will not be scientific, but political: a European-style compromise, based on the lowest common denominator’.[89]

Germany has always been a pioneer in the energy transition and especially in wind energy. The power of the environmental movement and the influence of the Green party in the political world and in society has contributed to this.[90] In 2014 the share of renewable energies had already risen to 34% in the energy mix.[91] In 2020, the objective of the 40% reduction in greenhouse gas emissions compared to 1990 was achieved despite the consequences of the COVID-19 crisis.[92] Before the Russian invasion in Ukraine, the country’s political elites believed that strategic reasons required the import of the major part of natural gas from Russia. More than half of its coal supplies and a third of its crude oil came from this same country.[93] The invasion in Ukraine pushed the country on the one hand to put an end to this dependence and on the other hand to increase the capacity of renewable energies.[94]

In Poland fossil fuels and particularly coal have always been at the forefront of the energy mix rising to almost 80% in the post-covid era.[95] Climate concerns were less present in Poland than in Germany and energy supply was most prioritized comparing to liberalization. The country has always pursued its energy independence from Russia. This position explains why Poland insisted on inserting a solidarity clause in the energy provisions of the TFUE. However, in 2020, 55% of the country's gas imports were coming from Russia.[96] That said, the progress that Poland has made in the sector of the transition to renewable energies should not be minimized. The electricity production of these sectors almost tripled between 2010 and 2020, their share in the Polish electricity mix increasing from 7% to 18%.[97] As for Hungary, at the start of the war the country took a diametrically different path in relation to the EU position regarding the independence of Russian gas. In July 2022, Budapest announced that Russia had started delivering more natural gas than agreed in their previous trade agreements via the Turkstream gas pipeline as the security of gas supply is an absolute priority for Hungary.[98] The Hungarian prime minister had even warned that phasing out Russian oil would devastate the Hungarian economy likening its impact to ‘a nuclear bomb’.[99]

Green hydrogen is also an area of ​​divergence between the different strategies of EU member states. It is a way to reduce dependence on fossil fuels in industries that cannot be powered by electricity.[100] On the one hand countries like Spain are increasing hydrogen production in homes using local renewable energies and on the other hand countries like Germany favor imports from third countries, thus creating new dependencies.[101]

3.2.  Energy solidarity in relation to the sovereignty of member states to determine their energy sources and the general structure of their energy supply

Article 4 TFEU categorizes energy among the fields of shared competence between EU and its member states.[102] Both EU and the member states’ institutions are entitled to legislate on energy matters. The scope and the methods of exercising this competence are precised by Articles 122(1) and 194(1) and 2 TFEU as already exposed. At the same time, the second part of paragraph 2 of the Article 194 TFEU provides that any action taken by the EU institutions in terms of energy policy shall not affect the member states’ right to determine the conditions for exploiting their energy resources, their choice between different energy sources and the general structure of their energy supply.

 It is therefore explicitly held that the energy mix prevailing in member states is dominantly decided by national administrations. Member states are the ones who conduct their own negotiations with third states and gas companies. They conclude their own international agreements on energy supply considering mainly or even exclusively their national interests.[103] The derogation from the rule of state sovereignty on the energy mix is nevertheless introduced by Article 192(2)(c) TFEU requiring unanimity in the decision-making procedure but only on the grounds of the adoption of measures in the field of the environmental and not energy policy. So, is there an inherent contradiction between different provisions of the TFEU and how would sovereignty on energy mix be compatible with the principle of energy solidarity introduced by the Articles 122(1) and 194(1) and (2) TFEU?

In the aftermath of the Russian invasion in Ukraine the EU legislator took a series of measures such as the Council Regulations 2022/1854, 2022/1369 and 2022/2578,[104] to respond to the energy crisis. The Commission’s REPower EU plan is also in the same direction.[105] The reaction of the EU’s institutions to the crisis, by means of secondary law and soft law, is indeed an expression of energy solidarity affecting inevitably to an extent the energy mix of member states. Does this necessarily lead to a restriction of energy sovereignty? A typical example demonstrating the friction between the principle of energy solidarity and the member state sovereignty on the choice of energy sources is the action brought by Poland before the CJEU claiming for the annulment of the above-mentioned Council Regulation 2022/1369 on coordinated demand-reduction measures for gas.[106] The regulation consists of the adoption of coordinated demand-reduction measures for gas. According to the Recital 11 of the regulation ‘[…] in order to promptly address the specific challenges of the ongoing and anticipated severe worsening of gas supply shortages and avoid distortions between Member States, a new instrument introducing the possibility for a mandatory gas demand reduction for all Member States should be established. It should become operational sufficiently in advance of autumn 2022’. 

More specifically, the Republic of Poland, by its action, contested the validity of the regulation claiming that its legal basis was incorrect and, consequently, that Article 192(2)(c) TFEU, combined with the second subparagraph of Article 194(2), was infringed since the disputed regulation was not adopted on the basis of Article 192(2)(c) TFEU which requires the Council to act unanimously, despite the fact that the above regulation significantly affects a Member State’s choice between different energy sources and the general structure of its energy supply.[107] Besides, the main objective of the contested regulation is to have a significant effect on the conditions for exploiting energy resources, the choice between different energy sources and the general structure of a Member State’s energy supply.[108] The position of Poland regarding this case has been criticized as ‘ironic’ since it was the very same member state who firstly insisted on including energy solidarity in the provisions of the TFEU and secondly initiated the above mentioned Opal Case.[109] Poland eventually withdrew its pleadings in the present action and an order was issued by the Court in this regard.[110] However, a ruling by the Court on this issue would have been especially noteworthy.

As M. Carnegie Labelle suggests, ‘energy sovereignty represents Member states’ authority to act, while energy solidarity signals alignment in the EU energy market’.[111] Energy sovereignty and energy solidarity are finally seen as the two pillars of the energy security system in EU. Once again, the example of the impact of the Russian invasion in Ukraine is eloquent. Several EU member states have been developing over the last two decades bilateral relationships with Russia in an effort of guaranteeing their energy independency. National governments focused almost exclusively on the energy mix that they considered most important for the security of their supply. Solidarity seemed to have taken a back seat in their strategies. But what was the result of this kind of approach? After Russian weaponization of natural gas, the lack of a European strategy based on the energy solidarity between member states exposed many EU countries to the risk of energy shortage. The shift of focus on their energy sovereignty resulted in the opposite of the expected outcome. The case of Germany is a typical one, among others.

Furthermore, it is not only the need for protection of national interests that calls for an energy solidarity-based approach of the member states’ strategies but also the functioning of the internal market itself. The latter requires members states to transfer a part of their energy sovereignty to the EU institutions.[112] The EU regulations and measures taken urgently after the Russian invasion to address energy shortages proved how the internal market and its mechanisms are not only a vector of economic and commercial development, but also, when associated with a ‘spirit of solidarity’, a path to security and protection against external threats. As has been very aptly remarked the concept of energy solidarity has turned the EU internal market, long term viewed as a soft power, to ‘a hard power punitive against Russia’.[113] Thereby, the notions of solidarity and national sovereignty complete each other and do not compete. Their common orientation is the objective of energy security and therefore energy independence of EU member states. In the EU context energy security should go beyond the traditional concept of security of supply. It should rather be understood in broader terms englobing protection against geopolitical and environmental risks.[114] As has pertinently been analyzed, ‘[t]he concept of energy security was continually extended to include further dimensions […] such as risk elimination, the role of infrastructure, the role of national energy policies, and the issue of sustainable development. In addition to the security of supply, the latest approaches cover a wider context of energy use, such as energy efficiency, environmental concern, consumption patterns, and technological progress’.[115]

The harmonization of the two notions requires redefining energy sovereignty in the context of EU. Energy sovereignty of member states’ is an integral part of their national sovereignty. Its main objective particularly in times of severe crisis is to guarantee security of supply, affordability and sustainability for a member state.[116] Nevertheless, within the EU the notion of national sovereignty and by extension the one of energy sovereignty is looked through a different prism. National energy sovereignty is combined with European energy sovereignty where integration and cooperation are the key elements to achieve the previously described goals.[117] As K. Westphal suggests, the traditional link of energy sovereignty to self-sufficiency seems to no longer have any place in the legal entity of EU.[118] Under these considerations, restrictions to a member state’s sovereign right to choose its energy mix are legitimate if they are proportionate to the objectives of security of supply, energy efficiency, interconnection of energy markets. The three steps of the proportionality test[119] are then again the guarantee for the respect of fundamental constitutional principles and core values linked to the preservation of security of member states. It is up to both the EU and the member states’ institutions to proceed to this test when adopting and implementing energy policies. 

4.   Final remarks

As appears from the above analysis of the primary and secondary law of the EU, and from the case law of the CJEU, the principle of solidarity is closely connected to energy security in the EU, as it contributes to ensuring supply for all, particularly the most vulnerable consumers, to protecting member states against external geopolitical risks and to the proper functioning of the internal market, which is itself a further guarantee of energy security. Moreover, the adoption of energy measures by the EU institutions to deal with the crisis after the Russian invasion in Ukraine and their implementation by the national administrations are a tangible expression of solidarity. They prove that EU member states can set aside their divergences when circumstances call for it. A principle that is at first glance vague or abstract can turn to an EU rule called upon to give cohesion to energy policy and to subjugate national objectives to European objectives with the necessary compromises. Yet, despite legislative and policy initiatives, the path towards achieving the goal of solidarity in the energy sector still remains long. 

Geopolitics and membership of the EU impose on member states to revisit notions such as security of supply, energy security and national interests and to reconsider them under a different prism, which is that of the interdependence within the EU. If this solidarity-based approach is not only deployed during periods of crisis but embraces both horizontally and vertically the relations between member states and EU, then they might be a step closer to the goal of energy security. Member states can act complementarily and EU should take advantage of each one’s dynamics; hydraulics for the Alps and Scandinavian countries, biomass for the countries of central Europe, solar energy for the Mediterranean countries, wind power for the countries on the coast of Atlantic and of the black sea.[120] It is by prioritizing solidarity that EU can ban or reduce free rider phenomena among its member states that can only undermine its cohesion. In any case, it would at least lead EU to establish itself as a power not only in the field of economy and democratic values but also capable of defending the strategic interests of its members regarding other powers dominating the energy sector, such as China, Russia or the United States of America.