United States

The use of hydrogen as a clean and renewable alternative to fossil fuels requires a suite of flammability mitigating technologies particularly robust sensors for hydrogen leak detection and concentration monitoring. To this end we have developed a class of lightweight optical hydrogen sensors based on a metasurface of Pd nano-patchy particle arrays which fulfills the increasing requirements of a safe hydrogen fuel sensing system with no risk of sparking. The structure of the optical sensor is readily nano-engineered to yield extraordinarily rapid response to hydrogen gas (<3 s at 1 mbar H2) with a high degree of accuracy (<5%). By incorporating 20% Ag Au or Co the sensing performances of the Pd-alloy sensor are significantly enhanced especially for the Pd80Co20 sensor whose optical response time at 1 mbar of H2 is just ~0.85 s while preserving the excellent accuracy (<2.5%) limit of detection (2.5 ppm) and robustness against aging temperature and interfering gases. The superior performance of our sensor places it among the fastest and most sensitive optical hydrogen sensors.

Microwave heating offers a number of advantages over conventional heating methods such as rapid and volumetric heating precise temperature control energy efficiency and lower temperature gradient. In this article we demonstrate the use of 2450 MHz microwave traveling wave reactor to heat the catalyst bed for thermo-catalytic upgrading of pyrolysis vapors. HZSM-5 catalyst was tested at three different temperatures (290 330  and 370°C) at a catalyst to biomass ratio of 2. Results were compared with conventional heating and induction heating method of catalyst bed. The yields of aromatic compounds and coke deposition were dependent on temperature and method of heating. Microwave heating yielded higher aromatic compounds and lower coke deposition. Microwave heating was also energy efficient compared to conventional reactors. The rate of catalyst deterioration was lower for catalyst heated in microwave system.

Photocatalytic hydrogen generation is one of the most promising solutions to convert solar power into green chemical energy. In this work a multi-component TiO₂–Ag–Cu₂O composite was obtained through simple impregnation-calcination of Cu₂O and subsequent photodeposition of Ag onto electrospun TiO₂ nanotubes. The resulting TiO₂–Ag–Cu₂O photocatalyst exhibits excellent photocatalytic H₂ evolution activity due to the synergetic effect of Ag and Cu₂O on electrospun TiO₂nanotubes. A dual Z-scheme charge transfer pathway for photocatalytic reactions over TiO₂–Ag–Cu₂O composite was proposed and discussed. This work provides a prototype for designing Z-scheme photocatalyst with Ag as an electron mediator.

To achieve the Paris Agreement’s long-term temperature goal current energy systems must be transformed. Australia represents an interesting case for energy system transformation modelling: with a power system dominated by fossil fuels and specifically with a heavy coal component there is at the same time a vast potential for expansion and use of renewables. We used the multi-sectoral Australian Energy Modelling System (AUSeMOSYS) to perform an integrated analysis of implications for the electricity transport and selected industry sectors to the mid-century. The state-level resolution allows representation of regional discrepancies in renewable supply and the quantification of inter-regional grid extensions necessary for the physical integration of variable renewables. We investigated the impacts of different CO₂ budgets and selected key factors on energy system transformation. Results indicate that coal-fired generation has to be phased out completely by 2030 and a fully renewable electricity supply achieved in the 2030s according to the cost-optimal pathway implied by the 1.5 °C Paris Agreement-compatible carbon budget. Wind and solar PV can play a dominant role in decarbonizing Australia’s energy system with continuous growth of demand due to the strong electrification of linked energy sectors.

Public attention to climate change challenges our locked-in fossil fuel-dependent energy sector. Natural gas is replacing other fossil fuels in our energy mix. One way to reduce the greenhouse gas (GHG) impact of fossil natural gas is to replace it with renewable natural gas (RNG). The benefits of utilizing RNG are that it has no climate change impact when combusted and utilized in the same applications as fossil natural gas. RNG can be injected into the gas grid used as a transportation fuel or used for heating and electricity generation. Less common applications include utilizing RNG to produce chemicals such as methanol dimethyl ether and ammonia. The GHG impact should be quantified before committing to RNG. This study quantifies the potential production of biogas (i.e. the precursor to RNG) and RNG from agricultural and waste sources in New York State (NYS). It is unique because it is the first study to provide this analysis. The results showed that only about 10% of the state’s resources are used to generate biogas of which a small fraction is processed to RNG on the only two operational RNG facilities in the state. The impact of incorporating a second renewable substitute for fossil natural gas “green” hydrogen is also analyzed. It revealed that injecting RNG and “green” hydrogen gas into the pipeline system can reduce up to 20% of the state’s carbon emissions resulting from fossil natural gas usage which is a significant GHG reduction. Policy analysis for NYS shows that several state and federal policies support RNG production. However the value of RNG can be increased 10-fold by applying a similar incentive policy to California’s Low Carbon Fuel Standard (LCFS).

The hazardous effects of pollutants from conventional fuel vehicles have caused the scientific world to move towards environmentally friendly energy sources. Though we have various renewable energy sources the perfect one to use as an energy source for vehicles is hydrogen. Like electricity hydrogen is an energy carrier that has the ability to deliver incredible amounts of energy. Onboard hydrogen storage in vehicles is an important factor that should be considered when designing fuel cell vehicles. In this study a recent development in hydrogen fuel cell engines is reviewed to scrutinize the feasibility of using hydrogen as a major fuel in transportation systems. A fuel cell is an electrochemical device that can produce electricity by allowing chemical gases and oxidants as reactants. With anodes and electrolytes the fuel cell splits the cation and the anion in the reactant to produce electricity. Fuel cells use reactants which are not harmful to the environment and produce water as a product of the chemical reaction. As hydrogen is one of the most efficient energy carriers the fuel cell can produce direct current (DC) power to run the electric car. By integrating a hydrogen fuel cell with batteries and the control system with strategies one can produce a sustainable hybrid car

In the search for new efficient photo-catalysts for hydrogen production through water splitting the main attention has been paid to tuning the band gap width and its position with respect to vacuum level. However actual electro-catalytic activity for the water oxidation reaction on a catalyst surface is no less important than those quantities. In this work we evaluate from first principles the thermodynamics of the reaction on relatively new candidates for water splitting: two-dimensional C₂N and that doped with phosphorus. We find that the 4-step reaction usually expected for water splitting will not proceed on these systems resulting in oxygen atoms left strongly adsorbed to the surface. Another option a 3-step reaction is also found to be unfavorable. We also test an effect of higher oxygen coverage on the reaction thermodynamics as suggested elsewhere. We find that indeed the doubled O-coverage makes the 4-step reaction feasible for the doped C₂N. However an unacceptably high anode potential is required to make this reaction proceed. We thus conclude that the materials under consideration may not be efficient electro-catalysts for water splitting.

The current status of a project is described which aims to demonstrate the technical and economic feasibility of converting the vast wind energy available over the globe’s oceans and lakes into storable energy. To this end autonomous high-performance sailing ships are equipped with hydrokinetic turbines whose output is stored either in electric batteries or is fed into electrolysers to produce hydrogen which then is compressed and stored in tanks. In the present paper the previous analytical studies which showed the potential of this “energy ship concept” are summarized and progress on its hardware demonstration is reported involving the conversion of a model sailboat to autonomous operation. The paper concludes with a discussion of the potential of this concept to achieve the IPCC-mandated requirement of reducing the global CO₂ emissions by about 45% by 2030 reaching net zero by 2050.

Here we report direct physical evidence that confinement of molecular hydrogen (H2) in an optimized nanoporous carbon results in accumulation of hydrogen with characteristics commensurate with solid H2 at temperatures up to 67 K above the liquid vapor critical temperature of bulk H2. This extreme densification is attributed to confinement of H2 molecules in the optimally sized micropores and occurs at pressures as low as 0.02 MPa. The quantities of contained solid-like H2 increased with pressure and were directly evaluated using in situ inelastic neutron scattering and confirmed by analysis of gas sorption isotherms. The demonstration of the existence of solid-like H2 challenges the existing assumption that supercritical hydrogen confined in nanopores has an upper limit of liquid H2 density. Thus this insight offers opportunities for the development of more accurate models for the evaluation and design of nanoporous materials for high capacity adsorptive hydrogen storage.

Reducing the cost of delivering hydrogen to fuelling stations and dispensing it into fuel cell electric vehicles (FCEVs) is one critical element of efforts to increase the cost-competitiveness of FCEVs. Today hydrogen is primarily delivered to stations by trucks. Pipeline delivery is much rarer: one urban U.S. station has been supplied with 800-psi hydrogen from an industrial hydrogen pipeline since 2011 and a German station on the edge of an industrial park has been supplied with 13000-psi hydrogen from a pipeline since 2006. This article compares the economics of existing U.S. hydrogen delivery methods with the economics of a high-pressure scalable intra-city pipeline system referred to here as the “HyLine” system. In the HyLine system hydrogen would be produced at urban industrial or commercial sites compressed to 15000 psi stored at centralized facilities delivered via high-pressure pipeline to retail stations and dispensed directly into FCEVs. Our analysis of retail fuelling station economics in Los Angeles suggests that as FCEV demand for hydrogen in an area becomes sufficiently dense pipeline hydrogen delivery gains an economic advantage over truck delivery. The HyLine approach would also enable cheaper dispensed hydrogen compared with lower-pressure pipeline delivery owing to economies of scale associated with integrated compression and storage. In the largest-scale fuelling scenario analyzed (a network of 24 stations with capacities of 1500 kg/d each and hydrogen produced via steam methane reforming) HyLine could potentially achieve a profited hydrogen cost of $5.3/kg which is approximately equivalent to a gasoline cost of $2.7/gal (assuming FCEVs offer twice the fuel economy of internal combustion engine vehicles and vehicle cost is competitive). It is important to note that significant effort would be required to develop technical knowledge codes and standards that would enable a HyLine system to be viable. However our preliminary analysis suggests that the HyLine approach merits further consideration based on its potential economic advantages. These advantages could also include the value of minimizing retail space used by hydrogen compression and storage sited at fuelling stations which is not reflected in our analysis.