Comparing prospective hydrogen pathways with conventional fuels and grid electricity in India through well-to-tank assessment

The present study uses Greenhouse Gases, Regulated Emissions, and Energy Use in Technologies Model (GREET), to compare hydrogen generated via multiple pathways (Natural gas, methanol reforming; coal, petcoke, biomass gasification etc) with the conventional fuels like diesel and compressed natural gas and grid electricity under Indian context through a comprehensive well to tank assessment based on net CO₂ equivalent emission and energy consumption. Limited availability of customized studies comparing hydrogen production and supply with other energy options in India distinguishes the present work as it provides a fresh insight into potential pathways for hydrogen production while assessing feedstock availability and raw water consumption. The study reveals that biomass gasification and solar electrolysis are among the least GHG emitting pathways to fill one unit of energy equivalent in the tank. Hydrogen produced through natural gas reforming is 70% less emission intensive and 38% more energy efficient than Indian grid electricity.     

The decline of the world’s energy intensity

Energy intensity of the total primary energy supply (TPES), total final energy consumption (TFC) and LOSSES in the conversion from TPES to TFC were analyzed for the World, OECD and Rest of the World (ROW) countries. LOSSES increased significantly for all groups of countries due to the increase of electricity production from coal in the period studied (1971–2008). Electricity share final consumption almost doubled, increasing from 8.8% to 17.2% in the period studied. However the energy intensity of LOSSES remained practically constant, which reflects the fact that the efficiency of electricity generation from coal (the main source of electricity) remained practically constant in that period. Despite the attractiveness of end-use devices running on electricity such as computers, which is typical of modern societies, the CO₂ emissions are bound to increase unless coal is replaced by less carbon emitting sources such as natural gas, renewables and nuclear energy.     

Baseload electricity from wind via compressed air energy storage (CAES)

This study investigates two methods of transforming intermittent wind electricity into firm baseload capacity: (1) using electricity from natural gas combined-cycle (NGCC) power plants and (2) using electricity from compressed air energy storage (CAES) power plants. The two wind models are compared in terms of capital and electricity costs, CO₂ emissions, and fuel consumption rates. The findings indicate that the combination of wind and NGCC power plants is the lowest-cost method of transforming wind electricity into firm baseload capacity power supply at current natural gas prices (∼$6/GJ). However, the electricity supplied by wind and CAES power plants becomes economically competitive when the cost of natural gas for electric producers is $10.55/GJ or greater. In addition, the Wind-CAES system has the lowest CO₂ emissions (93% and 71% lower than pulverized coal power plants and Wind-NGCC, respectively) and the lowest fuel consumption rates (9 and 4 times lower than pulverized coal power plants and Wind-NGCC, respectively). As such, the large-scale introduction of Wind-CAES systems in the U.S. appears to be the prudent long-term choice once natural gas price volatility, costs, and climate impacts are all considered.     

Improving the technical, environmental and social performance of wind energy systems using biomass-based energy storage

A completely renewable baseload electricity generation system is proposed by combining wind energy, compressed air energy storage, and biomass gasification. This system can eliminate problems associated with wind intermittency and provide a source of electrical energy functionally equivalent to a large fossil or nuclear power plant. Compressed air energy storage (CAES) can be economically deployed in the Midwestern US, an area with significant low-cost wind resources. CAES systems require a combustible fuel, typically natural gas, which results in fuel price risk and greenhouse gas emissions. Replacing natural gas with synfuel derived from biomass gasification eliminates the use of fossil fuels, virtually eliminating net CO₂ emissions from the system. In addition, by deriving energy completely from farm sources, this type of system may reduce some opposition to long distance transmission lines in rural areas, which may be an obstacle to large-scale wind deployment.     

Comparative assessment of greenhouse gas mitigation of hydrogen passenger trains

This paper examines a comparative assessment in terms of CO₂ emissions from a hydrogen passenger train in Ontario, Canada, particularly comparing four specific propulsion technologies: (1) conventional diesel internal combustion engine (ICE), (2) electrified train, (3) hydrogen ICE, and (4) hydrogen PEM fuel cell (PEMFC) train. For the electrified train, greenhouse gases from electricity generation by natural gas and coal-burning power plants are taken into consideration. Several hydrogen production methods are also considered in this analysis, i.e., (1) steam methane reforming (SMR), (2) thermochemical copper–chlorine (Cu–Cl) cycle supplied partly by waste heat from a nuclear plant, (3) renewable energies (solar and wind power) and (4) a combined renewable energy and copper–chlorine cycle. The results show that a PEMFC powertrain fueled by hydrogen produced from combined wind energy and a copper–chlorine plant is the most environmentally friendly method, with CO₂ emissions of about 9% of a conventional diesel train or electrified train that uses a coal-burning power plant to generate electricity. Hydrogen produced with a thermochemical cycle is a promising alternative to further reduce the greenhouse gas emissions. By replacing a conventional diesel train with hydrogen ICE or PEMFC trains fueled by Cu-Cl based-hydrogen, the annual CO₂ emissions are reduced by 2260 and 3318 tonnes, respectively. A comparison with different types of automobile commuting scenarios to carry an equivalent number of people as a train is also conducted. On an average basis, only an electric car using renewable energy-based electricity that carries more than three people may be competitive with hydrogen trains.     

Greenhouse gas emissions reduction by use of wind and solar energies for hydrogen and electricity production: Economic factors

This study addresses economic aspects of introducing renewable technologies in place of fossil fuel ones to mitigate greenhouse gas emissions. Unlike for traditional fossil fuel technologies, greenhouse gas emissions from renewable technologies are associated mainly with plant construction and the magnitudes are significantly lower. The prospects are shown to be good for producing the environmentally clean fuel hydrogen via water electrolysis driven by renewable energy sources. Nonetheless, the cost of wind- and solar-based electricity is still higher than that of electricity generated in a natural gas power plant. With present costs of wind and solar electricity, it is shown that, when electricity from renewable sources replaces electricity from natural gas, the cost of greenhouse gas emissions abatement is about four times less than if hydrogen from renewable sources replaces hydrogen produced from natural gas. When renewable-based hydrogen is used in a fuel cell vehicle instead of gasoline in a IC engine vehicle, the cost of greenhouse gas emissions reduction approaches the same value as for renewable-based electricity only if the fuel cell vehicle efficiency exceeds significantly (i.e., by about two times) that of an internal combustion vehicle. It is also shown that when 6000 wind turbines (Kenetech KVS-33) with a capacity of 350 kW and a capacity factor of 24% replace a 500-MW gas-fired power plant with an efficiency of 40%, annual greenhouse gas emissions are reduced by 2.3 megatons. The incremental additional annual cost is about $280 million (US). The results provide a useful approach to an optimal strategy for greenhouse gas emissions mitigation.     

Critical factors in the design,operation and economics of coal gasification plants: The case of the flexible co-production of hydrogen and electricity

Power generation from wind and solar sources is growing in importance, but requires back up from fossil fuel plants, greatly compromising fossil fuel plant economics. This includes the economics of most proposed IGCC–Hypogen type plant schemes which are intended to produce hydrogen and electricity, as well as capturing CO₂. IGCC–Hypogen plants, however, that are able to change the ratio of hydrogen to electricity will be able to operate at maximum capacity all of the time, switching from power generation to hydrogen production as the demand for these two forms of energy changes. Because of the need to provide power to the IGCC–Hypogen ancillaries, some hydrogen from the plant will have to be utilised to supply some of this power. A preliminary economic study examines how the plant could produce electricity and hydrogen at competitive prices.     

Wind energy,electricity, and hydrogen in the Netherlands

The curbing of greenhouse gases (GHG) is an important issue on the international political agenda. The substitution of fossil fuels by renewable energy sources is an often-advocated mitigation strategy. Wind energy is a potential renewable energy source. However, wind energy is not reliable since its electricity production depends on variable weather conditions. High wind energy penetration rates lead to losses due to power plant operation adjustments to wind energy. This research identifies the potential energetic benefits of integrated hydrogen production in electricity systems with high wind energy penetration. This research concludes that the use of system losses for hydrogen production via electrolysis is beneficial in situations with ca. 8 GW or more wind energy capacity in the Netherlands. The 2020 Dutch policy goal of 6 GW will not benefit from hydrogen production in terms of systems efficiency. An ancillary beneficial effect of coupling hydrogen production with wind energy is to relieve the high-voltage grid.     

Impact of hydrogen energy storage on California electric power system: Towards 100% renewable electricity

Decarbonization of the power sector is a key step towards greenhouse gas emissions reduction. Due to the intermittent nature of major renewable sources like wind and solar, storage technologies will be critical in the future power grid to accommodate fluctuating generation. The storage systems will need to decouple supply and demand by shifting electrical energy on many different time scales (hourly, daily, and seasonally). Power-to-Gas can contribute on all of these time scales by producing hydrogen via electrolysis during times of excess electrical generation, and generating power with high-efficiency systems like fuel cells when wind and solar are not sufficiently available. Despite lower immediate round-trip efficiency compared to most battery storage systems, the combination of devices used in Power-to-Gas allows independent scaling of power and energy capacities to enable massive and long duration storage. This study develops and applies a model to simulate the power system balance at very high penetration of renewables. Novelty of the study is the assessment of hydrogen as the primary storage means for balancing energy supply and demand on a large scale: the California power system is analyzed to estimate the needs for electrolyzer and fuel cell systems in 100% renewable scenarios driven by large additions of wind and solar capacities. Results show that the transition requires a massive increase in both generation and storage installations, e.g., a combination of 94 GW of solar PV, 40 GW of wind, and 77 GW of electrolysis systems. A mix of generation technologies appears to reduce the total required capacities with respect to wind-dominated or solar-dominated cases. Hydrogen storage capacity needs are also evaluated and possible alternatives are discussed, including a comparison with battery storage systems.     

Life cycle energy and environmental analysis of a microgrid power pavilion

Microgrids—generating systems incorporating multiple distributed generator sets linked together to provide local electricity and heat—are one possible alterative to the existing centralized energy system. Potential advantages of microgrids include flexibility in fuel supply options, the ability to limit emissions of greenhouse gases, and energy efficiency improvements through combined heat and power (CHP) applications. As a case study in microgrid performance, this analysis uses a life cycle assessment approach to evaluate the energy and emissions performance of the NextEnergy microgrid Power Pavilion in Detroit, Michigan and a reference conventional system. The microgrid includes generator sets fueled by solar energy, hydrogen, and natural gas. Hydrogen fuel is sourced from both a natural gas steam reforming operation and as a by‐product of a chlorine production operation. The chlorine plant receives electricity exclusively from a hydropower generating station. Results indicate that the use of this microgrid offers a total energy reduction potential of up to 38%, while reductions in non‐renewable energy use could reach 51%. Similarly, emissions of CO₂, a key global warming gas, can be reduced by as much as 60% relative to conventional heat and power systems. Hydrogen fuels are shown to provide a net energy and emissions benefit relative to natural gas only when sourced primarily from the chlorine plant. Copyright © 2006 John Wiley & Sons, Ltd.     

Fuel cells and energy networks of electricity,heat, and hydrogen: A demonstration in hydrogen-fueled apartments

A demonstration was performed to evaluate our proposal of a residential energy system based on fuel cells and energy networks of electricity, hot water, and hydrogen. The demonstration was conducted from April 2007 to March 2009 in a small apartment building constructed for experimental purposes in Osaka City. Three small proton exchange membrane fuel cells were installed, and the electricity and hot water from the fuel cells were shared among 6 units via an internal electricity grid and hot water pipe. A hydrogen production facility, a small storage device, and a hydrogen pipe were installed to supply hydrogen to the fuel cells. Six families went about their normal daily lives using this system. The energy flow from hydrogen production to consumption was demonstrated. The results of fuel cell operation, energy supply, and energy demand, as well as an analysis of primary energy saving and CO₂ emission mitigation are presented.     

The fossil energy/climate change crunch: Can we pin our hopes on new energy technologies?

There is a growing perception by society of the risks of dramatic global climate changes due to anthropogenic greenhouse gases, in particular energy related emissions of CO₂. This has spurred a renewed interest in carbon free or carbon neutral technologies for converting sources of renewable primary energy to electricity and to transportation fuels. However, it takes energy to produce energy, even when the primary source is energetically cost free, such as solar or wind. The aim of this letter is to present a model which allows the simulation of the energy costs of the deployment of a new energy technology. We show that the new technology may actually be an energy sink, instead of an energy source, relative to the global total primary energy supply (TPES) for many years or decades, depending on its intrinsic energy costs and deployment path, even though stated aims for its gross energy output are achieved. As expected, the energy payback time of the conversion devices, as well as fuel and maintenance costs are critical parameters. We illustrate the general model with simulations of the deployment of photovoltaic electricity, at global and national levels.     

Techno-economic analysis of a potential energy trading link between Patagonia and Japan based on CO2 free hydrogen

With regard to the Fukushima Daiichi accident in 2011 and Japan's goal to reduce CO₂ emission, the Japanese government strives for an emission free “hydrogen society” in which hydrogen will be the primary energy medium. The import of hydrogen generated by means of CO₂ free wind electricity from overseas can be a promising option for Japan's prospective energy supply. Besides different other factors like specific costs of electrolyzers and hydrogen shipment over long distances, the economically reasonable export of hydrogen based on renewable energy requires low levelized costs of electricity. Within the scope of this study, the underlying idea of a hydrogen supply chain is taken up and revisited by means of a spatially highly resolved wind energy potential analysis and a detailed investigation of the supply chain elements between Patagonia and Japan.Our analysis reveals that approximately 25% of the total land area in Patagonia would be eligible. Approx. 33,000 turbines with a minimum number of 4500 full-load hours with an overall capacity of about 115 GW can be positioned. Taking into consideration the related average number of 4750 full-load hours and an electrolysis efficiency of 0.7, this leads to a potential production of about 11.5 million tons/year of hydrogen. So the wind power potential of Patagonia would theoretically be sufficient for the assumed Japanese hydrogen demand of 8.83 million tons/year. The total hydrogen pretax cost would amount to approx. 4.40 €/kg_H2 at a liquid state at the harbor of Yokohama. Hence, the final specific costs of hydrogen in Japan depend on the expansion of wind power in Patagonia and therefore hydrogen based on wind energy can be cost-competitive to conventional fuels.     

Integrated fossil fuel and solar thermal systems for hydrogen production and CO2 mitigation

In most current fossil-based hydrogen production methods, the thermal energy required by the endothermic processes of hydrogen production cycles is supplied by the combustion of a portion of the same fossil fuel feedstock. This increases the fossil fuel consumption and greenhouse gas emissions. This paper analyzes the thermodynamics of several typical fossil fuel-based hydrogen production methods such as steam methane reforming, coal gasification, methane dissociation, and off-gas reforming, to quantify the potential savings of fossil fuels and CO₂ emissions associated with the thermal energy requirement. Then matching the heat quality and quantity by solar thermal energy for different processes is examined. It is concluded that steam generation and superheating by solar energy for the supply of gaseous reactants to the hydrogen production cycles is particularly attractive due to the engineering maturity and simplicity. It is also concluded that steam-methane reforming may have fewer engineering challenges because of its single-phase reaction, if the endothermic reaction enthalpy of syngas production step (CO and H₂) of coal gasification and steam methane reforming is provided by solar thermal energy. Various solar thermal energy based reactors are discussed for different types of production cycles as well.     

Life cycle sustainability assessment of electricity options for the UK

The UK electricity mix will change significantly in the future. This provides an opportunity to consider the full life cycle sustainability of the options currently considered as most suitable for the UK: gas, nuclear, offshore wind and photovoltaics (PV). In an attempt to identify the most sustainable options and inform policy, this paper applies a sustainability assessment framework developed previously by the authors to compare these electricity options. To put discussion in context, coal is also considered as a significant contributor to the current electricity supply. Each option is assessed and compared in terms of its economic, environmental and social implications, using a range of sustainability indicators. The results show that no one technology is superior and that certain trade‐offs must be made. For example, nuclear and offshore wind power have the lowest life cycle environmental impacts, except for freshwater ecotoxicity for which gas is the best option; coal and gas are the cheapest options (£74 and 66/MWh, respectively, at 10% discount), but both have high global warming potential (1072 and 379 g CO₂ eq./kWh); PV has relatively low global warming potential (88 g CO₂ eq./kWh) but high cost (£302/MWh), as well as high ozone layer and resource depletion. Nuclear, wind and PV increase some aspects of energy security: in the case of nuclear, this is due to inherent fuel storage capabilities (energy density 290 million times that of natural gas), whereas wind and PV decrease fossil fuel import requirements by up to 0.2 toe/MWh. However, all three options require additional installed capacity for grid management. Nuclear also poses complex risk and intergenerational questions such as the creation of 10.16 m³/TWh of nuclear waste for long‐term geological storage. Copyright © 2012 John Wiley & Sons, Ltd.     

Employment trends in the U.S. Electricity Sector, 2008–2012

Between 2008–2012, electricity generated (GWh) from coal, the longtime dominant fuel for electric power in the US, declined 24%, while electricity generated from natural gas, wind and solar grew by 39%, 154%, and 400%, respectively. These shifts had major effects on domestic employment in those sectors of the coal, natural gas, wind and solar industries involved in operations and maintenance (O&M) activities for electricity generation. Using an economic input–output model, we estimate that the coal industry lost more than 49,000 jobs (12%) nationally over the five-year period, while in the natural gas, solar, and wind industries, employment increased by nearly 175,000 jobs (21%). We also combine published ratios for jobs per unit of fuel production and per megawatt of power plant capacity with site-specific data on fuel production and power plant retirements, additions and capacity changes to estimate and map direct job changes at the county level. The maps show that job increases in the natural gas, solar and wind industries generally did not occur where there were significant job losses in the coal industry, particularly in West Virginia and Kentucky.     

Life cycle CO2 emissions from power generation using hydrogen energy carriers

Hydrogen energy carriers such as liquid hydrogen (LH₂), methylcyclohexane (MCH), and ammonia (NH₃) are promising energy vectors in the clean energy systems currently being developed. However, their effectiveness in mitigating environmental emissions must be assessed by life cycle analyses throughout the supply chain. In this study, while focusing on hydrogen energy carriers, life cycle inventory analyses were conducted to estimate CO₂ emissions from the following types of power generation plants in Japan: a hydrogen (H₂) mono-firing power plant using LH₂ or MCH that originated from overseas renewable electricity; and NH₃ co-firing with fossil fuel and NH₃ mono-firing power plants using hydrogen energy carriers that originated from overseas natural gas or renewable electricity. Parameters related to the supply chains were collected by literature surveys, and the Japanese life cycle inventory database was primarily used to calculate the emissions. From the results, CO₂ hotspots of the target supply chains and potential measures are identified that become necessary to establish low-carbon supply chains.     

Cogeneration of power and substitute of natural gas using biomass and electrolytic hydrogen

Storing renewable energy sources is becoming a very important issue to allow a further reduction of greenhouse gas emissions. Most of such energy sources generate electric power which not always can be conveniently transferred to the grid and also its conversion to hydrogen presents some critical aspects connected mainly to hydrogen distribution and storage.Electrolysis generates not only hydrogen, but also oxygen which could be used to burn biomass or waste products (oxycombustion) in power plants with the result to obtain an exhaust gas containing mainly water and CO₂. This last can be converted into a mixture of methane and hydrogen by reacting with electrolytic hydrogen, so that the power used for electrolysis is stored into a fuel which can be distributed and stored just like natural gas.In this paper, an innovative biomass fuelled plant has been designed and simulated for different layouts with an internal combustion engine as a main power system. Utilizing hydrogen and oxygen produced through electrolysis and applying a hydrogasification process, the plant produces electricity and a substitute of natural gas. The result of such simulations is that the electricity can be stored in a useful and versatile fuel with a marginal efficiency up to 60%.     

A linear diversity constraint - Application to scheduling in microgrids

Microgrids usually operate in disparate locations and may not be connected to the national grid. The potential sources of electricity in microgrids are wind farms, solar energy, biomass, tidal energy, among others. However, microgrids that are connected to the national grid are gaining importance, because they can supply electricity to the national grid when they have an excess and buy from it when they are in shortage. Such a symbiotic relationship with the national grid helps reduce investment in storage capacity and minimizes other operational costs. In this work, we develop a mathematical model MILP - (mixed integer linear programming) for scheduling operations in microgrids connected to the national grid. We allow several realistic features such as time constraints for the purchase/sale of power from/to the national grid; round trip efficiency of batteries; hydrogen generation, and limits on storage and retrieval rates from batteries/hydrogen tanks/natural gas tanks. Furthermore, to maintain diversity in the generation of electricity from multiple resources, we develop and impose a novel linear diversity constraint on the production schedule without sacrificing the ease of schedule implementation.     

The economic feasibility study of a 100-MW Power-to-Gas plant

Power-to-Gas (PtG) is a grid-scale energy storage technology by which electricity is converted into gas fuel as an energy carrier. PtG utilizes surplus renewable electricity to generate hydrogen from Solid-Oxide-Cell, and the hydrogen is then combined with CO₂ in the Sabatier process to produce the methane. The transportation of methane is mature and energy-efficient within the existing natural gas pipeline or town gas network. Additionally, it is ideal to make use of the reverse function of SOC, the Solid-Oxide-Fuel-Cell, to generate electricity when the grid is weak in power. This study estimated the cost of building a hypothetical 100-MW PtG power plant with energy storage and power generation capabilities. The emphasis is on the effects of SOC cost, fuel cost and capacity factor to the Levelized Cost of Energy of the PtG plant. The net present value of the plant is analyzed to estimate the lowest affordable contract price to secure a positive present value. Besides, the plant payback period and CO₂ emission are estimated.