THE KEY ROLE OF PTG TECHNOLOGIES IN THE ITALIAN ENERGETIC SYSTEM
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FOCUS ENEA_ The key role of PtG technologies in the Italian Energetic System Power to Gas (PtG), namely the conversion of electric energy into gas, hydrogen or synthetic metha- ne could allow European Countries to achieve the ambitious decarbonization targets foreseen in their energetic transition roadmaps. The paper underlines how those goals could be attained and the impacts over the Italian energetic system of the electric/gas network integration. The PtG technologies, their maturity, the challenges and the necessary habilitation actions are listed and analyzed. In this context, ENEA is developing several activities that cover different aspects of the value chain, starting from water electrolysis to methanation process. Currently in ENEA there is a multidisciplinary expertise on PtG that ranges from materials (membranes for electrolysers and fuel cells, catalysts for the chemical reaction of methane synthesis, microorganism for biological methane synthesis) to the study of processes at la- boratory and pilot scale. Other activities are focused on modelling and simulation related to processes and plants and to the regulatory aspects of coupling electric and gas networks. The general approach involves experimental activities on different scales and TRLs as well. Il Power to gas (PtG), ossia la conversione di energia elettrica in gas, idrogeno o metano sintetico, potrebbe consen- tire agli Stati Europei di raggiungere gli ambiziosi traguardi di decarbonizzazione previsti nelle loro roadmap verso la transizione energetica. L’articolo descrive come questi obiettivi possano essere conseguiti e gli impatti attesi sul si- stema energetico italiano dell’integrazione delle reti elettrica e del gas. Le tecnologie alla base del PtG, la loro matu- rità, le sfide e le necessarie azioni abilitanti sono elencate ed analizzate. In questo contesto, l’ENEA sta sviluppando molteplici attività che coprono aspetti differenti della catena del valore, dall’elettrolisi dell’acqua al processo di me- tanazione. Attualmente l’ENEA possiede competenze multidisciplinari sul PtG che spaziano dai materiali (membrane per elettrolizzatori e celle a combustibile, catalizzatori per la reazione chimica di sintesi del metano, microrganismi per la sintesi biologica del metano) allo studio dei processi a scala di laboratorio o di pilota. Altre attività riguardano la modellistica e la simulazione in fase di progetto di processi e impianti e gli aspetti regolatori dell’accoppiamento delle reti elettrica e gas. L’approccio generale comprende attività sperimentali su scale e TRL differenti. DOI 10.12910/EAI2021-026 by Paolo Deiana, Paola Gislon, Claudia Bassano (*) 134 Energia, ambiente e innovazione | 1/2021
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E
uropean and national energetic li Scenari Terna–Snam 2019” [4], the avoiding electricity grid implementa-
roadmaps foresee a continuous most ambitious scenario foresees a tions, through the electricity and gas
growth of renewable power growing green gases demand, up to 6.5 networks integration, the sector cou-
production [1,2]. The PNIEC Mm3/year in 2040, shared between syn- pling. Being the current gas grid and
[3] states to set the renewable target thetic methane and hydrogen. end-users immediately ready for syn-
up to 30% of the gross final energy PtG refer to the conversion of energy thetic methane use, PtM can be con-
consumption. PtG, allowing the long- from electrical to chemical, in the form sidered an enabling technology toward
term, even seasonal, electric energy of gaseous hydrogen (PtH – Power to the energy transition in the short term,
storage in 100% renewable vectors, Hydrogen) or other carbon compounds particularly in Italy, where the gas grid
its long distance transportation and hydrogen-derived, such as methane is extended and capillary; moreover, it
distribution, favours renewable power (PtM – Power to Methane). gives an opportunity to valorise una-
penetration and exploitation. Other Figure 1 illustrates the large variety of voidable carbon dioxide emissions.
PtG impacts comprise the decarbon- PtH/PtM employment: the hydrogen PtG term refers to a set of different pro-
ization of industrial and final energy from renewable power can be used lo- cesses and technologies. The hydrogen
user, especially of those hardly electri- cally in industrial processes, transport- production is attained by water elec-
fiable, as some industrial and mobili- ed by a grid for mobility applications, trolysis, at large energetic expenses.
ty sectors, and a larger sustainability, converted into methane or again into Currently three electrolytic processes
security and flexibility of the national power by feeding fuel cell systems, or can be considered market-ready: alka-
energetic system. can be stored. line electrolysers (AEL), the most ma-
The PtG technologies role is evidenced Another benefit of PtG is the valorisa- ture technology, polymeric membrane
in “Documento di Descrizione deg- tion of the existing gas infrastructures, electrolysers (PEM), and the most re-
Fig.1 PtG technological value chain [Source: IRENA 2019]
1/2021 | Energia, ambiente e innovazione 135FOCUS ENEA_ Fig.2 MENHIR plant details and thermal imaging camera during a test cent solid oxide electrolyzers (SOEC). and 950€/kWe for PEM. The declared Research and development ac- AELs use an alkaline solution (KOH or goal of the next “European Green tivities in ENEA NaOH) at atmospheric or slightly high- Deal” calls is to reach electrolysers er pressure; PEMs polymeric mem- plant sizes of 100MWe, consuming Power-to-Gas (both PtH e PtM) is a branes for protonic exchange; SOECs 49kWh/kg H2 (67% efficiency) and promising process ensemble that in- work at 700-800°C, their strength is re- 52kWh/kg H2 (64%) for alkaline and clude different technologies with dif- versibility, they can return power to the PEM electrolysers respectively, and ferent TRL values, some of those are grid if necessary. 480€/kW and 700€/kW CAPEX, re- commercially available however their The thermochemical methanation [5] spectively. The PtM process total ef- implementation in the power to gas is a catalytic (Sabatier) process: the re- ficiency is 5-8% lower than PtH; in chain is still being evaluated. Conse- action of H2 with CO2 to get synthetic a typical PtM plant, considering a quently, further R&I efforts are needed natural gas at 250-550°C and elevated 2500-3000€/kWe CAPEX, costs are to reduce technology and non-tech- pressures; CO2 can derived from bio- generally split into 40% electrolyser, nology costs, to improve performanc- gas, syngas from gasification, industrial 20% methanation, 40% storage, engi- es and to promote technology deploy- flues, or other. The reaction is highly ex- neering works and BOP. ment to market. othermic, making temperature control The more expensive green hydrogen Currently in ENEA there is a multidis- the most challenging aspect. The valori- and methane costs with respects to fos- ciplinary expertise on PtG that ranges sation of heat takes place for example in sil gases represent a definite drawback, from materials (membranes for elec- biogas upgrading plants, or industrial to be overcame by government incen- trolysers and fuel cells, catalysts for the processes or district heating networks tives, particularly in the assessment and chemical reaction of methane synthe- or greenhouses. technological development step. sis, biological process) to the study of A second methanation process, the bi- Normative to get hydrogen utilization, processes at laboratory and pilot scale. ological one, utilizes methanogen mi- transportation and storage feasible are Other activities are focused on model- croorganisms, as Archaea, acting as under development. A hydrogen and ling and simulation related to design of biocatalysts at 20-70°C and pressure methane green origin certification processes and plants and to the regu- higher than atmospheric one. and guarantee are welcome. latory aspects of coupling electric and PtG technological challenges include Enabling actions should break techno- gas networks. The general approach electrolyser development in dynam- logical, economic, financial and norma- involves experimental activities on dif- ic regimes, heat valorisation for cata- tive barriers: the role of governance, re- ferent scales and TRLs as well. lytic methanation, volume reduction search and industrial stakeholders and Specifically, the activities focused on for biological methanation, integra- their synergic involvement is crucial. innovative electrolysis technologies tion of the different technologies in Among the specific actions to be un- (SOEC, MCEC and AEM) and on bio- an optimized PtG system. dertook to reduce the gap with respect logical and catalytic methanation, pro- Currently electrolysers efficiency is in to conventional technologies are the cesses are reported in other articles of the 65-85% range; the largest plants development and validation of demon- this journal. are decades of MWe, costs are about strative projects in small energy district The MENHIR (MEthaNe and Hydro- 650€/kWe for alkaline electrolysers and a dedicated research plan. gen Infrastructure from Renewable) 136 Energia, ambiente e innovazione | 1/2021
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facility dedicated to study the PtM pro- is equipped with several sensors and Concrete actions to reduce the gap
cess is under construction at Casaccia a data acquisition system suitable to with conventional technologies can
Research Center. It is an infrastructure monitor and control the main operat- be found in the development of de-
aimed at optimizing different process ing process parameters. monstrative plants, in a research plan
features, such as catalysts, reactors MENHIR is a plant suitable for: eval- aimed at overcoming the barriers, in
type, heat management, temperature uating the dynamic behaviour of the a legislation that can accelerate the ef-
control and dynamic operation. Pres- singular components and of the inte- fective deployment and better define
ently, even with commercially avail- grated system (plant able to work at incentives to sustain creation of case
able methanation plants, research is load between 20 % and 100%) testing studies. Over a longer period, it would
considered still necessary to optimize different methanation catalysts and in- be desirable to design and build infra-
different process features, such as cata- tensified reactor, testing different pro- structures that involve the manage-
lysts, reactors type, heat management, cess methanation configuration (e.g. ment and large-scale use of hydrogen
temperature control and dynamic cooled or adiabatic reactor condition), and the storage of renewable energy in
operation. The electrolyser dynamic testing methanation unit performance the form of gas.
operation remains a challenge, since in different operating conditions of Research Institutions can play a fun-
variable loading and cycling operation temperature, pressure, inlet flows, typ- damental role in overcoming existing
can generate substantial performance ical of the implementation in Power scientific and technological barriers
losses and critical degradation of the To Gas (start up, shut-down, stand-by and helping policy makers to take the
constituent materials. e idle), testing upgrading methodolo- necessary actions to encourage the use
Moreover ENEA performs techno-eco- gies (e.g. membranes). of technology on a large scale. The con-
nomic evaluation of the whole PtG The plant is also fully flexible in its tribution of research should act syn-
value chains for different feasible path- modularity, so new hydrogen pro- ergically with the industrial world. In
ways and for the expected intermediate duction systems, new reactors or pro- particular, ENEA, in its institutional
and final products. This analysis aims cesses, can be inserted into the infra- capacity, is candidate to play an ef-
to evaluate replicability and scalability structure using the existing auxiliaries fective role in the development of
of PtG configuration considering the equipment. Finally, the plant is suita- the technologies involved in the PtG
different value chain (different final ble to be implemented with other en- chain, contributing to the develop-
use, sector coupling, geographic area, ergy storage systems such as batteries ment of individual technologies, from
energetic scenario). In this way, busi- to support the electrolyser or thermal the technological and regulatory as-
ness models aim to evaluate econom- storage for heat management of the pect, acting as stakeholder aggregator.
ic performance providing Levelized methanation process. In that field, ENEA has recently pro-
Costs of Hydrogen (LCoH), Energy posed the Hydrogen demo Valley Pro-
(LCoE), methane LCoX. ENEA carry Projects and perspectives ject aimed to create an infrastructural
out assessment of the expected im- hub for testing and demonstration of
pacts of the project on end-users and The reasons for the development of hydrogen technologies. It will cover
the community by means of key per- PtG in the Italian energetic system in- production, storage, distribution and
formance indicators (KPI) as well. clude strategic reasons as larger power utilisation of hydrogen (in blends with
network stability and a larger inde- natural gas as well), for applications in
The MENHIR plant pendence from foreign fossil energetic the energy, industrial, residential and
suppliers. In the Italian context, differ- transport sectors.
MENHIR plant is a modular, move- ent stakeholders are already actively The multifunctional infrastructure
able and containerized facility. The involved in PtG technologies, confirm- will be implemented in the Casaccia
facility is composed by an electrolyser ing the high level of interest and the Research Centre of ENEA, north of
and a methanation unit. The alkaline possible positive industrial growing in Rome, to act as a breeding ground for
type electrolyser is able to produce hy- the field. The PtG plants could carry hydrogen value chain technologies and
drogen up to 4 Nm3/h (24 kWe). The benefits in the assessment of a new in- services with the aim of accelerating
methanation section was designed dustrial chain. The different areas that their deployment in view of the energy
to test catalysts, reactors type, able to could benefit are both the end-users transition and overall decarbonisation.
work in cooled or adiabatic condi- and suppliers, as the energetic sector, Beside this context, ENEA has signed
tions, and process setups. The meth- particularly the energy from RES and two Collaboration Agreements with
anation section aims to produce a gas gas producers the chemical, engineer- SNAM and SGI, among the most im-
up to 1-2 Nm3/h, ready to be injected ing industry and the heavy CO2 emit- portant TSOs in the gas sector in Italy.
in the gas grid. The experimental plant ters/producers. Moreover, ENEA and Confindustria
1/2021 | Energia, ambiente e innovazione 137FOCUS ENEA_
have signed a collaboration agreement decarbonization targets foreseen in existing capillary national gas grid,
that aims to develop industrial hydro- their energetic transition roadmaps. ENEA has recently proposed the Hy-
gen value chains, innovative solutions The main features of a PtG introduc- drogen demo Valley Project and has in
and possible operational scenarios, tion are the possibility to store electric pipeline the realization of the MEN-
through a strengthened collaboration overproduction from renewables and HIR pilot plant.
between research and industry. A a complete fossil fuel replacement with
working group of ENEA and MISE is green gases in every sector, from energy (*) Paolo Deiana, Paola Gislon, Claudia
running support activities for com- production to industry, from mobility Bassano - Energy Storage, Batteries and
panies and defining a IPCEI hydro- to residential heating. In this context, Technologies for Hydrogen Production and
gen project. ENEA is developing several activities Utilization Laboratory
that cover different aspects of the value
Conclusions chain, starting from water electrolysis
to methanation process. In a frame-
Power to Gas could allow European work where PtG seems particularly
Countries to achieve the ambitious attractive for Italy due to its already
REFERENCES
1. EU COM (2018) 773. A Clean Planet for all − A European long-term strategic vision for a prosperous, modern, competitive
and climate neutral economy, In-depth analysis in support of the communication
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3. https://www.mise.gov.it/index.php/it/energia/energia-e-clima-2030
4. https://download.terna.it/terna/DDS%20libro%2009%2030%2017h15_8d745ced8696c60.pdf
5. Claudia Bassano, Paolo Deiana, Luca Lietti, Carlo Giorgio Visconti. P2G movable modular plant operation on synthetic meth-
ane production from CO2 and hydrogen from renewables sources. Fuel 253 (2019) 1071–1079.
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