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“Mediterranean Hydrogen Infrastructure. How to use” By M. Celozzi and G. Tomassetti

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Il Tazebao è lieto di ospitare il documento prodotto da Michelangelo Celozzi [1] – che a Firenze nel novembre del 2019 ha partecipato al seminario di studi “Questo è un nodo avviluppato” promosso da Regione Toscana insieme ad ARS e Nodo di Gordio – e Giuseppe Tomassetti [2] e pubblicato sul sito TEN (Trans Med Engineering Network). Questo il testo integrale dell’intervento.

Executive Summary

Hydrogen is not a game changer, but a technology studied for decades for several application. It is one of the possible options for energy storage to be assessed without bias and false hopes, starting from consolidated knowledge, considering the risks (storage and transport of H2) and opportunities offered by the H2 technology.

This paper, starting from the contents of the Study “Hydrogen without regrets”, presented by Agora in February 2021, proposes some general remarks about the opportunities offered by the development of a Hydrogen infrastructure in the Mediterranean Countries.



The energy transition has been talked about for many years. Now the pandemic has given the world an opportunity to make it happen more quickly than we could ever have imagined.

The World Energy Outlook 2020 of the IEA – International Energy Agency, focuses on the pivotal period of the next 10 years, exploring different pathways out of the crisis. The report provides the analysis of the pandemic’s impact: global energy demand is set to drop by 5% in 2020, energy-related CO2 emissions by 7%, and energy investment by 18%.

There is a real risk is that, once COVID-19 is under control, demand and emissions could bounce more strongly after the pandemic.

To prevent this from happening and set a new course it is necessary to prepare next future, to relaunch the economies of the countries hit by the pandemic recession on stronger and more sustainable basis.

If fail to prepare, prepare to fail.

According to the reference scenario of the IEA World Energy Outlook 2020 (Stated Policies Scenario), which reflects the announced policy intentions and targets released in 2020, global energy demand rebounds to its pre-crisis level in early 2023. However, this does not happen until 2025 in the event of a prolonged pandemic and deeper slump, we are still facing in this first quarter of 2021.

Slower demand growth reduces the outlook for oil and gas prices compared with pre-crisis trends. But large falls in investment increase the risk of future market volatility.

Renewables take starring roles in all the scenarios presented by the main analysts, with solar center stage. Some solar projects now offer some of the lowest cost electricity ever seen. In the Stated Policies Scenario, renewables meet 80% of global electricity demand growth over the next decade. If hydropower remains the largest renewable source at the global level, solar is the main source of growth, followed by onshore and offshore wind.

In this context of great uncertainty, conscious and responsive approach is needed, to make the most effective use of the once-in-a-lifetime opportunity represented by the offer of huge funds aimed at the post-pandemic economic recovery, based on energy as driver of productive and economic recovery, to finance the most promising investments, which are not always those proposed by the lobbies (even the most “green” ones), according to a scheduling based on a priority order, with objectives measurable and timebound at short, medium and long term.

The U.S.A. are also developing a national strategy on hydrogen, by considering the specific characteristics of the American energy system set in a global context, in which pragmatically they prefer to talk about reduction, rather than zeroing the carbon emissions.

We have therefore to consider the assessments made in the “Road map to a US Hydrogen economy” [3] and in an interesting article concerning an experience in the start-up phase in Texas [4].

In this framework, on February 11, 2021, Agora, the German Energy Transition think tank, presented a comprehensive study [5], “Hydrogen without regrets” (hereinafter “the Study), concerning next steps for the implementation of a Hydrogen infrastructure in Europe.

The Study has been subjected to public inquiry by Agora, and it represents an excellent opportunity to take stock of some crucial steps in developing a Hydrogen supply chain in Europe, and to set up the priorities for the use of the relevant financial resources made available by the Next Generation EU Plan to support the energy transition and the recovery of the European economies.

Hydrogen is not a game changer, as this technology has been studied for decades for several applications. It is a possible option for energy storage to be assessed without bias and false hopes, starting from consolidated knowledge.

So, starting from the contents of the Study, we propose some general remark for deepening how to use the Hydrogen in the Italian energy system, useful for evaluating the opportunities offered by a Mediterranean Hydrogen infrastructure.

H2 demand.

The analysis of the demand of the Study refers to the time horizons 2030 and 2050.

Current thermal uses of energy are largely linked to uses at temperatures below 100 °C, for which more efficient solutions than hydrogen already exist.

The same goes for short and not seasonal electricity storage, where the study focused on applications where H2 has a chemistry rather than energy value.

In recent years, the use of H2 has found applications in refineries and in the production of ammonia, a very promising development guideline to produce, store and transport new synthesis gases with reduced carbon content.

In the next decade (2030-2040), uses will also develop for the direct reduction of ferrous minerals. At the same time the use of H2 in refineries will gradually decrease due to the reduction of fossil fuels, replaced by the chemical regeneration of plastics.

The overall demand for H2 by 2050 in these three sectors of use (steel, ammonia and regeneration) is estimated to amount, for the whole EU, to 270 TWh /y, in terms of energy, fairly constant in the period under review; the forecast of annual demand in Italy is concentrated in petrochemicals refineries and in steel mills, for about 16 TWh /y.

H2 offer.

In the Study, he alternative between blue H2 (derived from fossil methane with CO2 CCSS, capture sequestration and storage) and green H2 (derived from water electrolysis, powered by electricity produced from renewable sources) was examined; however this window of technical-economic choice is quite narrow and should remain valid only for a few years, so it could only affect those countries, such as Norway and UK, which have already developed the technologies for the CSS (Carbon Sequestration and Storage) and the related technical regulations and standards, for which the context makes provision for shorter authorization procedures.

For the other countries it is believed that the resources for the realization of projects based on the use of Blue H2, and above all on the storage and remote delivery, would be nullified by the expected reduction in the production costs of Green H2, i.e. traditional market conditions of electrolyzers is about 750 €/kW, and it is expected to reach 450 €/kW in 2030 and 260 €/kW in 2050, but for which it is expected that the stimulus of the market with adequate incentives (very likely) could reduce these costs up to about 96 €/kW and 67 €/kW, in the same years.

The reduction in electrolyzers’ costs would favor the Mediterranean Countries of Central and Southern Europe, which could more effectively use photovoltaics, despite the greater seasonality and lower load factors of the PV plants (about 1500 h/y in Sicily), compared to the Northern countries, where the interest for offshore wind power is greatest (with shallow sea waters and high load factor of the plants of about 4,000 h/y).

H2 Delivery.

This issue is extremely relevant, given the deep knowledge of the hydrogen technology, and of the well-known problems of storage and transport.

Then this is the most difficult problem to solve, especially where data and information are less certain and consolidated: in this case it is not a question of replacing a component in a supply chain already active and structured over decades, but it is a question of hypothesizing a completely new supply chain, which must meet to a series of parameters often dependent on the territorial constraints.

To be clear: it is impossible merely substitute natural gas with hydrogen in the gas supply chain.

Preferred uses will be those concentrated, constant and guaranteed.

The natural gas industry today guarantees supplies, mixing internal production and imports, thanks to a network of interconnected gas pipelines, extended at a regional level, and a series of re-gasifiers, powered by tankers for the transport of LNG. To manage seasonal variations in gas demand, depleted gas fields are used as reservoirs, where existing.

Such an infrastructure, dedicated to H2, does not exist; on the other hand, the expected volumes of H2 consumption are only a small percentage of current methane consumption, so it is possible, considering the complexity of the safety aspects for distributed uses, such infrastructure will not be born even in the future.

The infrastructures for the final use of H2, in fact, do not have the constraint of the local availability of sources of energy raw materials, therefore their development is foreseen, at least in an initial phase, without connections among them, around the points of end consumption, with a close link between production and use.

The production of H2 from renewable sources, and by photovoltaics, reflects all the intermittency problems, both daily and seasonal, of electricity production from renewable sources, therefore it requires a storage infrastructure, of electricity or hydrogen, of dependent dimensions to the characteristics of the single plant.

The study indicates for southern Europe the need of storage for about 40% of annual consumption; the methane stored in the Italian tanks, even with all the existing redundancies, is about 20% of the annual consumption.

However, there are no experiences of H2 storage in natural cavities, nor are the technical rules to be followed to adapt them to this function defined; the study does not exclude that in the future depleted methane reservoirs used for methane storage can be used as hydrogen reservoirs, but it is believed that the only solution that can receive rapid approval is that of caves in salt deposits.

For very small volumes, storages in metal tanks are possible, but with high construction and operational costs (high pressure required of about 700 bar), connected to safety risks [6].

The study mentions the problems of the possible use of existing methane pipelines for the distribution of H2 but does not investigate the relevant technical problems (leaks and brittle fracture), nor the regulatory ones.

The study evaluated the possible use of H2 blended with methane in natural gas networks, but with negative results due to the loss of value of the product compared to the investment costs.

Findings of the Study

The Study evaluates the costs for the different delivery solutions and concludes that four European areas are considered as candidates for local hydrogen networks dedicated to concentrated uses in activities hard to decarbonize:

  • one between Dunkirk and Hamburg, through Belgium and Holland,
  • a second on the Catalan coast,
  • a third between Poland and Lithuania,
  • finally, a fourth in the Balkans.

Italy is excluded due to the lack of salt deposits for potential storages.

Only a case study on the Tuscan coast is cited, with H2 carried by sea (probably in the form of NH3) with the use of metal tanks; however, the cost for storage is about three times higher than that the H2 production.

A proposal for the Mediterranean

Based on the assessments reported in the Study, some comments can be added on the development not so much of an Italian hydrogen supply chain, since its isolation from the European context is not likely, but on the characteristics of possible projects that can be localized in Southern Mediterranean, and related development times.

Any project needs a preventive “tailor-made” technical-economic feasibility study, to identify the specific industrial direct use of Hydrogen, the applicable technologies, the energy storage technology (short-term or seasonal) to meet the needs of continuous operation of the end user application in face of the intermittency of the primary energy source, the integration with existing electricity and gas infrastructures.

In most of the Southern Mediterranean Countries the choice of (photovoltaic) PV technology for the electricity decarbonization is usually the most appropriate.

The H2 local applications take priority, where the greater volumes of demand allow to bear the H2 production costs in the short-medium term.

The widespread applications require greater in-depth analysis, both for the volumes involved and for the safety issues related to the H2 storage and distribution, also due to the lack of technical standards for the authorization of construction and operation.

Some proposals have already been presented to the Italian Ministry of Economic Development, for building an “Important Project of Common European Interest” (IPCEI) to enhance the opportunities of H2 uses as part of the industrial policy initiatives promoted by the Italian Government in cooperation with other EU Member States and the European Commission.

Among these, one proposal concerns the feasibility study of an integrated plant for the use of hydrogen produced with electricity generated by a PV plant dedicated to powering an electrolyzer, which would increase the penetration of renewable sources in uses so far powered exclusively by fossil fuels, such as high temperature thermal uses (> 200 °C).

Since hydrogen can be produced electrolytically even using sea water, this type of application would be replicable throughout the Mediterranean.

The project hypothesis is based on the innovative use of mature technologies, to accelerate development times, evaluating the possibility of adopting components already industrialized and available on the market to produce H2, reducing performance risks and development costs.

The proposal concerns:

  • The Feasibility Study for the construction and location of an integrated hub for green H2 production and connection to a selected end use and to national grids (gas and electricity), comprising four sections:

o Photovoltaic power generation plant dedicated to the H2 production.

o Electric Storage System and Electricity System Integration, to regulate the feeding of the electrolyzer system.

o Electrolyzer System for H2 production

o Hydrogen delivery system directly to the end use

The feasibility study will identify a list of possible end uses of H2 and related possible locations, by considering the context in which H2 can be set, depending on topology of the existing electricity and gas infrastructures, the potential industrial end use sites and the climatic characteristics, as well as the engineering choices for the optimal management of the hydrogen supply (risk analysis, stability, adjustment).

  • Public inquiry. The results of the study will be submitted to an international public inquiry, to acquire possible contributions based on different experiences.
  • Cost Benefit Analysis to optimize the size and location of the plant
  • Preliminary design and Terms of Reference for the FID (Final Investment Decision) and Call for Tender for the construction and operation of the plant.

Rome, April 2021

  1. Eng. Michelangelo Celozzi – Executive President – TEN – Trans Med Engineering Network;
  2. Eng. Giuseppe Tomassetti – Vice President – FIRE – Italian Federation for the Rational Use of Energy;
  3. ROAD MAP TO A US HYDROGEN ECONOMY – Reducing emissions and driving growth across the nation.
  4. “How the Lone Star State is building a green hydrogen future” –  By Johnny Wood 2021-03-23 –  https://spectra.mhi.com/
  5. No-regret hydrogen” – Charting early steps for H infrastructure in Europe- Agora Energiewendehttps://static.agora-energiewende.de/fileadmin/Projekte/2021/2021_02_EU_H2Grid/2021-02-11_Presentation_H2GRID.pdf
  6. Hydrogen is highly flammable and explosive. To obtain liquid hydrogen, hydrogen gas, as a product, e.g., from an electrolyzer, it is placed in a container, far from heat sources and electrical sources, after having purged it with an inert gas (e.g., nitrogen or argon), to avoid the danger of explosions due to the air otherwise present. The pressure in the tank is adjusted to a value slightly higher than the standard atmospheric one (equal to about 1 atmosphere), then the tank temperature is lowered to a temperature below -253 ° C (close to absolute zero), at which the gas at atmospheric pressure assumes the liquid state. This temperature increases with increasing pressure (until about 700 bar at 15 °C in appropriate tanks). Relevant are the risks of fire, explosion, asphyxiation, cold burns (in contact with skin or eyes). A mixture of 96% air and 4% hydrogen is explosive indoors. In an open environment, hydrogen in contact with the air burns almost spontaneously, producing a pale flame, practically invisible in daylight. The risks of leaks from tanks and pipes are high, as the hydrogen molecule is very small. Various metallic materials, in contact with hydrogen under certain conditions, are subject to embrittlement and / or corrosion by stress; for this reason, the compressed hydrogen steel cylinders are built with a particular alloy.
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