Assessment of power-to-power renewable energy storage based on the smart integration of hydrogen and micro gas turbine technologies

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Hydrogen can be transported by fuel cell electric truck for an average distance of 200 km per trip.

“Hydrogen transportation by Fuel Cell Electric Truck for an average distance of 200 km per trip.”

Probably not a substantial claim: may not pass S4 (based).

The round-trip efficiency of a power-to-power energy storage system with micro gas turbines is between 22% and 29%.

“Round-trip e_ciency of P2P energy storage system with micro gas turbines between 22% and 29%.”

May combine two claims.

The specific energy consumption of AEC and PEMEC electrolysers changes when the operating conditions of the electrolyser change, regardless of the technology of choice (Eq. (3)), and when different materials or integration layouts are adopted.

“Furthermore, the specific energy consumption of these electrolysers also changes when the operating conditions of the electrolyser change, regardless of the technology of choice (Eq.( 3)), and when different materials or integration layouts are adopted.”

May combine two claims.

For cases based on SOEC, the highest round-trip efficiency is obtained when hydrogen is stored in the form of MH (≈29.0%), followed closely by compressed-H2 (≈27.9%), and LH2 at a further distance (≈25.6%).

“For cases based on SOEC, the highest efficiency is obtained when hydrogen is stored in the form of MH (z29.0%),followed closely by compressed-H 2 (z27.9%), and LH 2 at a further distance (z25.6%).”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

If a FCET is considered, around 3840 kg of LH2 can be transported in a single trip, which is around four times the energy that can be transported when considering compressed-H2 or MH.

“If a FCET is considered, around 3840 kg of LH 2 can be transported in a single trip, which is around four times the energy that can be transported when considering compressed-H 2 or MH.”

• AssumptionRests on an assumption: Regardless of storage technology, higher H2 densities lead to lower energy cost of hydrogen transportation/distribution.

May combine two claims.

For metal hydride storage, storage is almost free energy-wise if a suitable heat source is available or if the metal hydride operates at ambient temperature.

“The case of MH is different to the other two storage options since storage is almost free energy-wise, if and where there is a heat source available at a suitable temperature or when the metal hydride is suitable for operation at ambient temperature (see Section Metal Hydrides (MH)).”

May combine two claims.

For AEC or PEMEC electrolysers, they experience the same fluctuations when different storage media are considered (Fig. 9): efficiency lower than 20% for LH2 and around 21-22% for compressed-H2 or MH.

“and they experience the same fluctuations when different storage media are considered (Fig. 9): efficiency lower than 20% for LH 2 and around 21e22% for compressed-H 2 or MH.”

May combine two claims.

If the value corresponding to one of the existing LH2 plants were selected (for instance, 11.9 kWh/kg H2 corresponding to case B19), the round-trip efficiency would go down to 22.7% and the energy consumption of the LH2 facility would take 20% of the total energy demand of the power-to-power storage system.

“Actually, if the value corresponding to one of the existing LH 2 plants were selected (for instance, 11.9 kWh=kg H2 corresponding to case B19), h round-trip would go down to 22.7% and the energy consumption of the LH 2 facility would take 20% of the total energy demand of the power-to-power storage system.”

May combine two claims.

For liquefied-H2 storage, storage accounts for 10%-13% of total energy consumption, while distribution takes only 0.4%.

“As a result, storage accounts for 10%e13% of the total energy consumption whereas distribution takes 0.4% of the total energy in only.”

May combine two claims.

SOEC electrolyser energy consumption is 40 kWh/kg H2, compared to 52 kWh/kg H2 for AEC and 53 kWh/kg H2 for PEMEC.

“A closer look into the energy consumed by the electrolyser in each case, Fig. 7, reveals that this energy consumption is largely reduced when SOECs are used as opposed to either AEC or PEMEC: 40 kWh=kg H2 against 52 kWh=kg H2 and 53 kWh=kg H2 respectively.”

May combine two claims.

The operation of an ideal electrolyser with null losses would require 33.33 kWh/kg H2, which translates into a potential 13-15% gain in round-trip efficiency.

“In particular, the operation of an ideal electrolyser with null losses would require 33.33 kWh=kg H2 what translates into a potential 13e15% gain in h round-trip .”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Pumped hydroelectric storage is the oldest and most mature energy storage technology.

“Pumped Hydroelectric Storage (PHS) is the oldest and most mature technology.”

May combine two claims.

The capital cost of proton-exchange membrane electrolysers is 2 to 3 times higher than that of alkaline electrolysers, though it is expected to decrease to about 600-1300 EUR/kW in the following decade.

“However, the Capital Cost (CapEx) of PEMECs is 2e3 times higher than for AEC, even if this figure is expected to decrease to some 600e1300 V/kW in the following decade [17,37,38].”

• cites [17]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [37]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [38]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Grey hydrogen is 5 to 8 times cheaper than green hydrogen according to several techno-economic assessments.

“In particular, grey hydrogen is 5e8 times cheaper than green hydrogen according to several techno-economic assessments of the technology [2,10,17].”

• cites [2]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [10]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [17]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Proton-exchange membrane electrolysers have a smaller footprint and much better response to rapid load changes.

“PEMECs are characterised by a smaller footprint and much better response to rapid load changes.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Blue hydrogen has specific emissions of 0.2 t CO2 per t H2.

“Blue hydrogen: same as grey hydrogen but incorporating Carbon Capture and Sequestration (CCS) techniques.Specific emissions decrease to 0.2 t CO2 /t H2 .”

• cites [17]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S4 (based).

Unlike pumped hydroelectric storage or compressed air energy storage, hydrogen can be produced in situ wherever there are power and water supplies.

“Unlike PHS or CAES, hydrogen can be produced in-situ wherever there are power and water supplies.”

May combine two claims.

Because of variable renewable energy intermittency, limited large-scale energy storage, and larger variable renewable energy shares, the grid must still rely on conventional power generation technologies when variable renewable energy is not available.

“This, along with the very limited options for large-scale energy storage available today and the increasingly larger share of VREs into the energy mix, implies that the grid must still rely on conventional power generation technologies to generate electricity when VRE is not available.”

• AssumptionRests on an assumption: Conventional power generation technologies are very reliable but feature high emissions of greenhouse gases and, in some cases, other hazardous emissions such as nuclear waste.

Probably not a substantial claim: may not pass S3 (load-bearing).

Approximately EUR 60 billion of investment is required by 2030 to achieve cost-effectiveness of hydrogen technologies.

“Approximately EUR 60 billion investment is required by 2030 to achieve cost-effectiveness of hydrogen technologies, which can be facilitated through the following five drivers: reduced market uncertainty, larger improvement-for-investments for technology boost, hybrid solutions, increasing utilisation rates in distribution networks and investments in blue/green hydrogen.2”

• cites [10]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

For alkaline and proton-exchange membrane electrolysers, the settling time after a load change is on the order of seconds, whereas start-up and shutdown are on the order of minutes.

“These studies report that the settling time after a load change is in the order of seconds whereas start-up and shutdown is in the order of minutes.”

• cites [43]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Thermoneutral operation of an electrolyser, when carried out reversibly, determines the minimum energy that must be supplied for sustained operation: 285.8 kJ/mol if water is supplied as liquid or 241.8 kJ/mol if the feed is vapour.

“Operation of the electrolyser at constant temperature is called thermoneutral operation and, when carried out reversibly, determines the minimum amount of energy that must be supplied to the electrolyser for sustained operation: 285.8 kJ mol À1 if water is supplied as a liquid or 241.8 kJ mol À1 if the feed is vapour.”

May combine two claims.

Variable renewable energies such as wind and solar are intermittent, and their availability for power generation depends mainly on local weather conditions that can be predicted accurately only 24-36 h in advance.

“Variable renewable energies like wind or solar are characterised for being an intermittent source of energy whose availability for power generation depends mainly on local weather conditions, which can be predicted accurately 24e36 h in advance only [3].”

• cites [3]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

As electrochemical losses of the electrolyser cell increase, the consumption of electrical work increases and efficiency decreases.

“As the electrochemical losses of the electrolyser cell increase, the consumption of electrical work increases with respect to the aforesaid value (237.2 kJ mol À1 at standard pressure and temperature) and efficiency decreases accordingly.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Pumped hydroelectric storage accounts for 96% of total energy storage capacity among all technologies.

“It represents the largest form of storage today, accounting for 96% of the total energy storage capacity amongst all technologies [8].”

• cites [8]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Worldwide hydrogen production is expected to reach 240 Mt by 2050.

“From these values, hydrogen production worldwide is expected to reach 240 Mt by 2050 [2], when it will play a key role in the mobility, power and heat sectors even if this production would cover 7.5% of the global energy demand worldwide only.”

• cites [2]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Interest in power-to-power energy storage systems has been increasing steadily in recent times, in parallel with larger shares of variable renewable energy in the power generation mix worldwide.

“The interest in Power-to-Power energy storage systems has been increasing steadily in recent times, in parallel with the also increasingly larger shares of variable renewable energy (VRE) in the power generation mix worldwide [1].”

• cites [1]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Green hydrogen has a potentially null carbon footprint.

“Green hydrogen: renewable energy sources RES are used in this case so the associated carbon footprint is potentially null.”

• cites [17]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Classified as probably not a substantial claim.

The power-to-power system considered in this work is limited to a maximum power output of around 500 kWe.

“Hence, the P2P system considered here is limited to a maximum power output of around 500 kWe.”

Probably not a substantial claim: may not pass S3 (load-bearing).

More than twenty applications where hydrogen can become a cost-competitive low-carbon solution before 2030 have been identified in a recent report by the Hydrogen Council.

“More than twenty applications where hydrogen can become a cost-competitive low-carbon solution before 2030 have been identified in a recent report by the Hydrogen Council [10], needing a large investment effort if they are to be developed and taken to the market.”

• cites [10]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Around 143 power-to-gas projects producing either hydrogen or methane have been operated in recent decades, some starting as far back as 1988.

“In this latter group, around 143 PtG projects producing either hydrogen or methane have been operated in the last decades, some of them starting as far back as 1988 [11,12].”

• cites [11]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [12]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Water electrolysis is the dominant technology for producing green hydrogen because of its fairly high conversion efficiency and direct use of electricity, unlike other technologies that rely mostly on heat.

“Water electrolysis is the dominant technology for the production of green hydrogen owing to its fairly high conversion efficiency and direct use of electricity, as opposed to other technologies which rely mostly on heat.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Worldwide hydrogen production by the end of 2018 was estimated at 74 Mt, 97% of which was produced through steam reforming of natural gas and therefore with large carbon dioxide emissions.

“The estimated worldwide production of hydrogen by the end of 2018 was 74 Mt, 97% of which was produced through steam reforming of natural gas (methane) and, therefore, with large emissions of carbon dioxide.”

• cites [2]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [17]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Grey hydrogen has specific emissions estimated at 11 t CO2 per t H2.

“Grey hydrogen: the primary energy source is natural gas and the specific emissions of the process are estimated at 11 t CO2 /t H2 .”

• cites [17]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The efficiency of solid oxide electrolysis is above 80% referred to the low heating value of hydrogen and close to 100% when considering the high heating value.

“The net result is that the efficiency of SOEC is above 80% referred to the Low Heating Value (LHV) of hydrogen and close to 100% when considering the High Heating Value (HHV), given that the total energy consumption remains approximately constant in the aforesaid temperature range.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Germany hosts the largest number of power-to-gas plants, with 64 projects.

“Germany hosts the largest number of these plants, with 64 PtG projects, but the stimulus given by governments around the world will expectedly see other countries catching up in the next years [13e16].”

• cites [13e16]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

As of 2019, there were 56 active power-to-gas projects based on hydrogen, with an installed electric capacity of 24.1 MWe.

“As of 2019, there were 56 active PtG projects based on hydrogen, with an installed electric capacity of 24.1 MWe [11].”

• cites [11]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Alkaline electrolysis is the most mature electrolyser technology and yields the lowest capital cost.

“The most mature technology is AEC and it yields the lowest capital cost (CapEx).”

Probably not a substantial claim: may not pass S3 (load-bearing).

Recent investigations have shown that further optimisation of the concept would enable an even lower power requirement of approximately 5.9 kWh/kg H2.

“recent investigations have shown that further optimisation of the concept would enable an even lower power requirement of approximately 5.9 kWh=kg H2 [59,60].”

• cites [59]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [60]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The lower energy consumption of SOEC is due to its working temperature and implies that a higher grade heat source is needed to raise the temperature of and evaporate the inlet water stream to operate SOEC at rated conditions.

“This difference comes about because of the working temperature, as explained in Section Hydrogen production, and implies that a higher grade heat source which can both raise the temperature of and evaporate the inlet water stream is needed in order to operate the SOEC at the rated conditions.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Hydrogen is commonly produced at close to ambient pressure and temperature, in the range from 1 to 30 bar and from 303 to 333 K.

“Hydrogen is commonly produced at close to ambient pressure and temperature, in the range from 1 to 30 bar and from 303 to 333 K, as stated in section Hydrogen production.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based). May combine two claims.

mGT-P2P also provides a high-grade heat source which makes it suitable for CHP applications.

“Additionally, it also provides a high-grade heat source which makes it suitable for CHP applications.”

• AssumptionRests on an assumption: The electric efficiency of micro gas turbines is lower than fuel cells (>55%) and reciprocating internal combustion engines (>45%), but mGTs offer high grade heat for Combined Heat and Power (>250 C).

May combine two claims.

The time period for which hydrogen energy storage is most attractive is on the order of days to months; for shorter or longer storage periods, other technologies exhibit a better trade-off between discharge time and storage efficiency.

“Nevertheless, despite this flexibility, the term-period for which hydrogen energy storage is most attractive is in the order of days to months.For shorter or longer storage periods, other technologies exhibit a better trade-off between discharge time and efficiency of storage [6].”

• cites [6]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Metal hydrides are characterised by a higher density, exceeding 115 kg_H2/m3.

“These new compounds are characterised by a higher density, exceeding 115 kg_H 2 /m3 (Fig. 3).”

May combine two claims.

If the hydrogen production and consumption nodes are at the same location and sufficient space (land area) is available, lower storage pressures can be used, making compressed-H2 storage very attractive.

“Nevertheless, if the hydrogen production and consumption nodes are at the same location and sufficient space (land area) is available, lower storage pressures can be used, making this option very attractive.”

May combine two claims.

In spite of the maximum round-trip efficiency of around 30% reported in this work for mGT-P2P energy storage solutions, there is still a large margin for improvement.

“Finally, it is to note that in spite of the maximum h round-trip of around 30% reported in this work for mGT-P2P energy storage solutions, there is still a large margin for improvement.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Hydrogen can be stored in different ways and for as long as required, unlike other technologies that cannot be used for long-term energy storage.

“This means that hydrogen can be stored in different ways and for as long as it is required, as opposed to other technologies which cannot be used for long-term energy storage.”

Classified as probably not a substantial claim. May combine two claims.

Hydrogen has the highest gravimetric density among fuels but one of the lowest densities.

“Hydrogen is known to be the fuel with the highest gravimetric density but with the main shortcoming of having one of the lowest densities.”

May combine two claims.

When diaphragm compressor operation is discontinuous with frequent start/stop, the lifetime of the diaphragm can decrease substantially, leading to more frequent servicing and higher maintenance costs.

“However, when operation is discontinuous (frequent start/stop), the lifetime of the diaphragm can decrease substantially, which means more frequent servicing and, therefore, higher maintenance costs.”

May combine two claims.

Predictions from different world energy organisations [17,37,38] estimate that the energy consumption of electrolysers is expected to decrease by a few kWh/kg H2 in the next decade, leading to a round-trip efficiency improvement of around 3-5% (one third of the theoretical efficiency gain).

“Even if this is a theoretical limit that cannot be achieved in practice, predictions from different world energy organisations [17,37,38] estimate that the energy consumption of electrolysers is expected to decrease by a few kWh/kg H2 in the next decade, leading to a Dh round-trip improvement of around 3e5% (one third of the theoretical efficiency gain).”

• cites [17]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [37]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [38]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Hydrogen compression is the most common means to store and distribute hydrogen in relatively small quantities of 5-10 kg H2 per tank.

“Hydrogen compression is the most common means to store and distribute hydrogen in relatively small quantities, 5e10 kg H2 /tank.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Gas Turbines are catching up more quickly with Fuel Cells due to lessons learned from hydrogen co-firing in the last decades.

“Gas Turbines (GT) are one of the technologies that is catching up more quickly with FCs, thanks to the lessons learned from hydrogen co-firing in the last decades [83e86].”

• cites [83e86]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

The second most influential driver energy-wise is storage, and hydrogen liquefaction brings about a substantial round-trip efficiency reduction.

“It becomes clear that the second most influential driver energy-wise is storage and, in this regard, hydrogen liquefaction brings about a substantial h round-trip reduction.”

May combine two claims.

Despite the maximum round-trip efficiency of around 30% reported for micro gas turbine power-to-power energy storage solutions, there is still a large margin for improvement.

“Finally, it is to note that in spite of the maximum h round-trip of around 30% reported in this work for mGT-P2P energy storage solutions, there is still a large margin for improvement.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The pressure at which hydrogen is compressed ranges from 50 to 400 bar for stationary applications and up to 900 bar for mobility applications.

“The pressure at which hydrogen is compressed depends on the application and it ranges from 50 to 400 bar for stationary applications and to 900 bar for mobility applications (where high density is a critical requirement).”

May combine two claims.

Hydraulically driven dry-running reciprocating compressors are a viable alternative for frequent transient or discontinuous operation and enable high delivery pressures up to 3000 bar with oil-free, leakage-free, and technically abrasion-free compression.

“In applications with more frequent transient and/or discontinuous operation, hydraulically-driven dryrunning reciprocating compressors are a viable alternative.They also enable high delivery pressures of up to 3000 bar [50] with also oil, leakage and technically abrasion free compression.”

• cites [50]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Compressed-H2 requires high-pressure storage vessels (type III & IV [96]) and a compression system able to handle high pressure ratios (>10:1), which translates into high capital and operating costs.

“Compressed-H 2 requires high-pressure storage vessels (type III & IV [96]) and a compression system able to handle high pressure ratios ( > 10:1), what translates into high capital and operating costs.”

• cites [96]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S2 (checkable). May combine two claims.

This would take this technology closer to and beyond cost-effectiveness, setting it on the map of essential technologies to enable carbon neutrality by 2050.

“This would take this technology closer to and beyond cost-effectiveness, setting it on the map of essential technologies to enable carbon neutrality by 2050.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The operating principle of diaphragm compressors ensures oil-free and leakage-free compression with high purity of the outlet flow.

“The operating principle of diaphragm compressors ensures oil and leakage free compression with high purity of the outlet flow.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Isentropic compression and reversible intercooled compression differ, with the latter resembling an isothermal compression process.

“Fig. 4a shows the differences between isentropic (reversible and adiabatic) and reversible, intercooled compressions, the latter of which resembles an isothermal compression process.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Substances with higher energy densities, such as ammonia or syngas, can be produced using hydrogen as feedstock, which facilitates transportation but incurs higher energy losses due to the additional process.

“Other substances with higher energy densities, such as ammonia or syn-gas, can be produced using hydrogen as feedstock.This facilitates transportation but incurs higher energy losses due to the incorporation of an additional process where large amounts of energy are consumed (either as heat, mechanical power or both).”

May combine two claims.

The efficiency of micro gas turbines could increase to around 40% [92,100] in the next decade and the combination of SOEC/SOFC and mGT in so-called hybrid systems would boost power generation efficiencies to values as high as 55-60% [101].

“Indeed, the efficiency of these engines could increase to around 40% [92,100] in the next decade and the combination of SOEC/SOFC and mGT in socalled hybrid systems would boost power generation efficiencies to values as high as 55e60% [101].”

• cites [92]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [100]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites [101]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• AssumptionRests on an assumption: Micro gas turbines can run at full capacity just a few minutes after start-up and their electric efficiency ranges from 25% for smaller units (<100 kWe) to almost 40% for larger units (≈500 kWe).

Probably not a substantial claim: may not pass S3 (load-bearing).

Hydrogen compression implies large pressure ratios, typically higher than 30:1, enabled by volumetric machines such as reciprocating or diaphragm compressors.

“This implies large pressure ratios (typically higher than 30:1), enabled by volumetric machines such as reciprocating or diaphragm compressors.”

May combine two claims.

Only liquid cryogenic or solid metal hydride storage would make a difference to hydrogen energy density, but these processes are either highly energy intensive or not suitable for large-scale hydrogen storage.

“Only liquid (cryogenic) or solid (metal hydrides) storage would make a difference but these processes are either highly energy intensive or not suitable for large-scale hydrogen storage.”

May combine two claims.

The critical advantage of the mGT-P2P option over these technologies is that it is independent from geographical constraints and it can be installed almost anywhere where renewable electricity and water are available, in addition to the advantage of dealing with an energy vector as it is hydrogen.

“Additionally, the critical advantage of the mGT-P2P option over these technologies is that it is independent from geographical constraints and it can be installed almost anywhere where renewable electricity and water are available in addition to the advantage of dealing with an energy vector as it is hydrogen.”

May combine two claims.

Data on CapEx of a P2P system are scarce given the early stage of development of most hydrogen technologies [94], most of them not fully commercialised yet, and when available they incorporate a large deal of uncertainty.

“Such data are nevertheless scarce given the early stage of development of most hydrogen technologies [94], most of them not fully commercialised yet, and when available they incorporate a large deal of uncertainty.”

• cites [94]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

The implementation of a hydrogen liquefaction plant would expectedly have a negative impact on the total capital cost of the storage facility, even though economic aspects are not considered in this study.

“In addition, even though economic aspects are not considered in this study, the implementation of a hydrogen liquefaction plant would expectedly have a negative impact on the total capital cost of the storage facility.”

• AssumptionRests on an assumption: Liquefied-H2 features a density of ≈78 kg/m3 and the liquefaction process is highly energy intensive.

May combine two claims.

Compression work is influenced not only by inlet conditions and outlet pressure but also by compressor type and how the compression process is carried out.

“Compression work is influenced not only by inlet conditions and outlet pressure but also by compressor type and, linked to this, how the compression process is carried out.”

May combine two claims.

The energy density of hydrogen at ambient conditions is much lower than that of methane, ethane, methanol, or ammonia, and even at storage pressures as high as 300 bar it remains significantly lower.

“It is observed that the energy density of hydrogen at ambient conditions is much lower than that of other gases (e.g., methane, ethane), liquids (e.g., methanol) or solids (e.g., ammonia); moreover, even if the storage pressure of hydrogen were increased to values as high as 300 bar, the energy density would still be significantly lower.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Many of the challenges in using metal hydrides are related to the thermodynamics and kinetics of dehydrogenation, which determine the hydrogen discharge rate and the heat supply needed to enable efficient hydrogen desorption.

“many of the challenges in using such materials are related to the thermodynamics and kinetics of dehydrogenation, which determine the hydrogen discharge rate and the heat supply needed to enable efficient hydrogen desorption from the metal hydride.”

• cites [73e75]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Losses along the LH2 pathway are intrinsic to the utilisation of a cryogenic fluid; they occur during transfer between vessels and when the fluid warms due to heat transfer from the environment.

“Losses along the LH 2 pathway are intrinsic to the utilisation of a cryogenic fluid.They occur when hydrogen in these conditions is transferred between two vessels (liquefaction plant to tank-truck, tank-truck to storage station, storage station to end-user through a pump or compressor, and eventually final use in a fuel cell or other power generation device) and when the fluid is warmed up due to”

• cites [56]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Probably not a substantial claim: may not pass S3 (load-bearing).

Hydrogen loading and unloading processes in metal hydrides are influenced mostly by thermodynamic and kinetic aspects.

“As such, these process are influenced by thermodynamic and kinetic aspects mostly [72].”

• cites [72]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

May combine two claims.

Diaphragm compressors compress small to medium flow rates of hydrogen efficiently and attain high to extremely high pressure ratios of more than 5000:1.

“Diaphragm compressors compress small to medium flow rates of hydrogen efficiently, attaining high to extremely high pressure ratios of more than 5000:1 [50].”

• cites [50]Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.