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2022 ◽  
Vol 9 ◽  
Author(s):  
Koteswara R. Putta ◽  
Umesh Pandey ◽  
Ljubisa Gavrilovic ◽  
Kumar R. Rout ◽  
Erling Rytter ◽  
...  

By adding energy as hydrogen to the biomass-to-liquid (BtL) process, several published studies have shown that carbon efficiency can be increased substantially. Hydrogen can be produced from renewable electrical energy through the electrolysis of water or steam. Adding high-temperature thermal energy to the gasifier will also increase the overall carbon efficiency. Here, an economic criterion is applied to find the optimal distribution of adding electrical energy directly to the gasifier as opposed to the electrolysis unit. Three different technologies for electrolysis are applied: solid oxide steam electrolysis (SOEC), alkaline water electrolysis (AEL), and proton exchange membrane (PEM). It is shown that the addition of part of the renewable energy to the gasifier using electric heaters is always beneficial and that the electrolysis unit operating costs are a significant portion of the costs. With renewable electricity supplied at a cost of 50 USD/MWh and a capital cost of 1,500 USD/kW installed SOEC, the operating costs of electric heaters and SOEC account for more than 70% of the total costs. The energy efficiency of the electrolyzer is found to be more important than the capital cost. The optimal amount of energy added to the gasifier is about 37–39% of the energy in the biomass feed. A BtL process using renewable hydrogen imports at 2.5 USD/kg H2 or SOEC for hydrogen production at reduced electricity prices gives the best values for the economic objective.


2022 ◽  
Vol 11 (1) ◽  
pp. 51
Author(s):  
John Vourdoubas

Mitigation of climate change requires the replacement of traditional energy technologies with novel low carbon energy systems. The possibility of using a fuel cell and a hybrid energy system consisted of a fuel cell and solar-PV panel for energy generation in Venizelio hospital located in Crete, Greece has been investigated. The size, the heat and electricity generated, the H2 required and the capital cost of the fuel cell and the solar-PV system covering the energy requirements in the hospital have been estimated. Existing research has indicated that fuel cells using H2 can cover the heat and electricity needs in various buildings. Our results indicated that a fuel cell at 1 397 KW can produce annually 4 895 MWhel and 4 895 MWhth covering all the electricity and heating needs in Venizelio hospital producing excess heat at 2 451 MWhth. The capital cost of the fuel cell has been calculated at 4 191 000 € while the required H2 at 367.5 tons/year. All the energy requirements of the hospital can be also covered with a hybrid energy system consisted of a fuel cell and a solar-PV system. The size of the fuel cell has been estimated at 697.5 KW and the cost at 2 092 500 €. The electricity generation was at 2 444 KWhel and its heat production at 2 444 KWhth. The size of the solar-PV system has been evaluated at 1 629 KWp and the cost at 1 634 000 €.The annual electricity generation was at 2 451 MWhel. The capital cost of the hybrid energy system at 3 726 500 € is lower than the cost of the fuel cell alone at 4 191 000 €. Our results indicated that the use of novel benign energy systems with zero carbon emissions in Venizelio hospital is technically and economically feasible.


2022 ◽  
Author(s):  
Jonathan E Menard ◽  
Brian A Grierson ◽  
Thomas G Brown ◽  
Chirag Rana ◽  
Yuhu Zhai ◽  
...  

Abstract Recent U.S. fusion development strategy reports all recommend that the U.S. should pursue innovative science and technology to enable construction of a Fusion Pilot Plant (FPP) that produces net electricity from fusion at low capital cost. Compact tokamaks have been proposed as a means of potentially reducing the capital cost of a fusion pilot plant. However, compact steady-state tokamak FPPs face the challenge of integrating a high fraction of self-driven current with high core confinement, plasma pressure, and high divertor parallel heat flux. This integration is sufficiently challenging that a dedicated sustained-high-power-density (SHPD) tokamak facility is proposed by the U.S. community as the optimal way to close this integration gap. Performance projections for the steady-state tokamak FPP regime are presented and a preliminary SHPD device with substantial flexibility in lower aspect ratio (A=2-2.5), shaping, and divertor configuration to narrow gaps to a FPP is described.


2022 ◽  
Vol 32 (1) ◽  
pp. 47-56
Author(s):  
Paul D. Gottlieb ◽  
Robin G. Brumfield ◽  
Raul I. Cabrera ◽  
Daniel Farnsworth ◽  
Lucas Marxen

Water availability, quality, and management, particularly under climate change constraints and fierce competition for water resources, are challenging the sustainability of intensively irrigated nursery crops. We created an online tool to estimate costs and benefits of a water recycling investment at a commercial nursery, given data on the operation input by the user. The online tool returns a “regulatory risk score” based on the user’s drought and pollution risk. Then, using a partial budget approach, it returns net present value of the investment, upfront capital cost, and expected change in annual cash flow. The present article seeks to cross-validate this computer model with results reported in the case study literature. We aggregated data on 38 nurseries and greenhouses profiled in five published studies into a meta study dataset. These data validated the computer tool’s assumptions about the relationship of operation size to total capital cost. Separate simulations on the profitability effects of varying public water rates and price premia due to green marketing corroborated the findings of earlier studies. A major finding of the simulation analysis not previously emphasized in the literature is that capital cost and profit vary significantly with the precise method that is used to size the recapture pond. A “minimalist” approach to this decision is likely to be the most cost-effective, but growers should also keep stormwater runoff and other issues of environmental best practices in mind.


2022 ◽  
pp. 239-278
Author(s):  
Gavin Towler ◽  
Ray Sinnott
Keyword(s):  

2021 ◽  
Author(s):  
Waleed Alhazmi ◽  
Maher Alabdullatif

Abstract This paper presents an unparalleled engineering assessment conducted to evaluate the feasibility of pre-investing in O2 enrichment technology, with the purpose of increasing the processing capacities of conventional air-based sulfur recovery units (SRUs). Ultimately, the goal is to minimize the overall number of required SRUs for a greenfield gas plant and, consequently, capture a significant cost-avoidance opportunity. The technology review revealed that a high-level O2 enrichment can double the processing capacity of air-based SRU, depending on the H2S content in acid gas. As H2S mole fraction in feed increases, the debottlenecking capability increases. For the project under assessment, the processing capacity of air-based SRUs showed a maximum increase of 80%. On the contrary, operating with high O2 levels, will elevate SRU reaction furnace temperature, and mandates installing high-intensity burners, along with special control and ESD functions, to manage potential risk and ensure safe operation. Additionally, the liquid handling section of SRUs (condensers, collection vessels, degassing vessels, sulfur storage tanks) should be enlarged to accommodate more sulfur production. Typically, the enriched oxygen can be supplied from air separation units (ASUs), which entails significant capital cost. Apart from these special design considerations, there are several advantages for adopting this technology. Oxygen enrichment removes significant nitrogen volumes, which reduces loads on Claus, tail gas treatment, and thermal oxidizer units. Hence, lower capital cost for new plants is acquired due to equipment size reduction. In addition, higher HP steam production and less fuel gas consumption are achieved. Conventionally, O2 enrichment technology is employed in the initial design stage or used to retrofit operating SRUs facilities. However, it is unique to consider O2 enrichment-design requirements as part of new air-based SRUs design for phased program development. The objective is to enable smooth transition to fully O2 enrichment operated SRUs at a later phase of the project without the need for any design modification. This exceptional pre-investment strategy has resulted into reducing the required number of SRUs at phase II from eight to five units; and accordingly, a significant cost avoidance was captured.


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