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Hydrogen is a key input to industrial processes. In western Canada, there is a significant demand for hydrogen for industrial purposes, both to upgrade bitumen and as a chemical agent. The key driver for this research is the need to assess options for the energy industry to lower its carbon footprint by using hydrogen produced from renewable sources. The environmental impacts associated with hydrogen production through water electrolysis using the electricity generated from a wind power plant are evaluated in this paper. A life cycle assessment was done to determine the greenhouse gas (GHG) emissions per unit mass of produced hydrogen by considering the emissions starting from the extraction of wind energy to the production of hydrogen. An uncertainty analysis was conducted to assess the effects of variations of different input parameters on the GHG footprint of hydrogen produced from wind. The total GHG emissions of a wind-based hydrogen production plant are estimated to be 0.68 ± 0.05 kg CO 2 eq./kg H 2 , 65% of which are from the construction of the wind power system. The results are compared with those of conventional fossil fuel-based systems. The overall GHG emissions from wind-based hydrogen production are about 94% lower than those associated with hydrogen production through steam methane reforming (SMR). Natural gas-based hydrogen production emissions are mainly found in the plant operation stage. For wind-to-hydrogen systems, the manufacturing and installation of the systems have significant environmental impacts. However, the hydrogen produced from wind energy can significantly reduce the GHG footprint of the energy industry. [ABSTRACT FROM AUTHOR]

Hydrogen production via steam methane reforming (SMR) dominates the supply to refining complexes worldwide, resulting in significant greenhouse gas (GHG) emissions. There is a considerable demand for clean hydrogen pathways that are economically competitive with SMR. The development of a 563 MW integrated wind-hydrogen model with energy storage is proposed. The model utilizes real-time wind energy data to ascertain the optimal size of the electrolyser, the number of electrolyser units and the battery (energy storage) capacity that will yield a minimum hydrogen production cost, whilst functioning in a liberalized electricity market with dynamic prices. The optimal plant configuration consists of 81 units of a 3496 kW (760 Nm 3 /hr) electrolyser and 360 MWh (60 units) of battery capacity. For the minimum hydrogen production cost determined ($9.00//kg H 2 ), the wind farm accounts for 63% of this cost. Hence, if existing wind farm assets are used, such that the investment cost of building the wind-hydrogen plant does not include the wind farm costs, the hydrogen production cost is reduced to $3.37/kg H 2 . For a particular electrolyser-battery configuration, it was observed that the minimum hydrogen production cost occurs when their respective capacity factors are approximately equivalent. The benefits of energy storage are limited by the decrease in overall plant efficiency, which results from the use of the battery. For the techno-economic conditions considered in this paper, hydrogen production costs from wind powered electrolysis ($3.37 to $9.00/kg H 2 ) are uncompetitive with SMR/SMR-CCS ($1.87 to $2.60/kg H 2 ). [ABSTRACT FROM AUTHOR]

Hydrogen (H 2) can play a critical role in global greenhouse gas (GHG) mitigation. Photocatalytic water splitting using solar radiation is a promising H 2 technology. Titanium dioxide (TiO 2) and carbon nitride (g–C 3 N 4)–based photocatalysts are the most widely used photocatalytic materials because of their activity and abundance. Several attempts have been made to improve the photocatalytic performance of these materials in terms of their activity level, life span, response to visible radiation, and stability. However, the environmental impacts of these modifications are often not included in existing studies. This research, therefore, develops a cradle-to-grave life cycle assessment (LCA) framework to evaluate and compare the GHG footprints of four alternative pathways: TiO 2 nanorods and fluorine-doped carbon nitride quantum dots embedded with TiO 2 (CNF: TNR/TiO 2), g-C 3 N 4 , and g-C 3 N 4 /BiOI composite. Unlike most studies that focus only on certain stages such as laboratory-scale photocatalytic fabrication, this study includes utility-scale cell production, assembly, operation, and end of life to give a more accurate and precise environmental performance estimation. The results show that g-C 3 N 4 /BiOI has the lowest GHG footprint (0.38 kg CO 2 eq per kg of H 2) and CNF: TNR/TiO 2 has the lowest energy payback time (0.4 years). In every pathway, energy use in material extraction processes makes up the largest GHG contribution, between 83% and 89%. Sensitivity and uncertainty analyses were conducted under the impact of various input parameters on the life cycle GHG emissions of hydrogen production. Photocatalytic water splitting is highly feasible for adaptation as a mainstream hydrogen production pathway in the future. • LCA of H 2 production via photocatalytic water splitting is conducted. • GHG emissions range from 0.33 to 1.15 kg of CO 2 eq per kg of H 2 produced. • Material extraction has the largest GHG emissions; 56–67% of total emissions. • System is scaled up to produce 5 tonnes of H 2 per day. • H 2 produced has 95% less GHG emissions than steam methane reforming. [ABSTRACT FROM AUTHOR]

Jurisdictions are looking into mixing hydrogen into the natural gas (NG) system to reduce greenhouse gas (GHG) emissions. Earlier studies have focused on well-to-wheel analysis of H 2 fuel cell vehicles, using high-level estimates for transportation-based emissions. There is limited research on transportation emissions of hythane, a blend of H 2 and NG used for combustion. An in-depth analysis of the pipeline transportation system was performed for hythane and includes sensitivity and uncertainty analyses. When hythane with 15% H 2 is used, transportation GHG emissions (gCO2eq/GJ) increase by 8%, combustion GHG emissions (gCO2eq/GJ) decrease by 5%, and pipeline energy capacity (GJ/hr) decreases by 11% for 50–100 million m3/d pipelines. Well-to-combustion (WTC) emissions increase by 2.0% without CCS, stay the same with a 41% CCS rate, decrease by 2.8% for the 100% CCS scenario, and decrease by 3.6% in the optimal CO 2 -free scenario. While hythane contains 15% H 2 by volume only 5% of the gas' energy comes from H 2 , limiting its GHG benefit. [Display omitted] • A model is developed to assess well-to-combustion (WTC) greenhouse gas (GHG) emissions of hythane. • A hythane blend of 15% H 2 and 85% natural gas is assessed. • Transportation GHG emissions increase by 8% and combustion GHG emissions decrease by 4%. • Without carbon capture, WTC GHG emissions increase by 2%. • Steam methane reforming of hydrogen with 90% carbon capture will reduce WTC GHG emissions by 3%. [ABSTRACT FROM AUTHOR]