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Designing a green hydrogen project requires careful consideration of multiple technical parameters. This comprehensive guide will walk you through the essential calculations needed for your pre-feasibility study, from energy demand assessment to cost analysis. Whether you're transitioning existing operations to hydrogen or starting a new hydrogen-based process, this guide will help you make informed decisions.
Step 1: Know Your End Use Energy Demand
Understanding your energy requirements is the foundation of any hydrogen project. This step involves determining how much energy your process needs on a timely basis. The approach differs depending on whether you're:
- Converting existing operations (using historical consumption data)
- Starting a new process (calculating from process parameters)
Practical Example: Steam Boiler Conversion
Let's consider a steam boiler conversion project:
- Steam production: 1.5 tonnes at 7 barg
- Feedwater temperature: 100°C
- Operation: 24/7, 365 days per year
- Boiler efficiency: 90%
Using our Steam Boiler Calculator, we can determine:
- Annual energy requirement: 8,656 MWh
- Fuel requirement (accounting for efficiency): 9,522 MWh/year
- Daily energy demand: 26,088 kWh/day
Step 2: Calculate Your H₂ Demand
Converting your energy demand to hydrogen mass requires understanding hydrogen's energy content. The key parameter here is the Low Heating Value (LHV) of hydrogen, which is 33.33 kWh/kg (distinct from the High Heating Value, HHV, of 39.44 kWh/kg).
Understanding LHV vs HHV
The difference between LHV and HHV is crucial in hydrogen calculations. Learn more about these differences and their impact on your calculations.
Calculating H₂ Demand
Using our previous example:
- Daily energy demand: 26,088 kWh
- H₂ LHV: 33.33 kWh/kg
- Daily H₂ demand: 783 kg H₂
For different fuel inputs or applications, use our Hydrogen Demand Calculator to determine your specific requirements.
Step 3: Calculate Your Electrolyser Size
Electrolyser sizing requires careful consideration of two critical parameters: efficiency and capacity factor.
Key Parameters
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Efficiency: The percentage of input energy converted to hydrogen energy content.
This can be expressed in two ways:
- As a percentage (e.g., 75% efficiency)
- In kWh/Nm³ (energy required to produce 1 m³ of H₂ at normal conditions)
When manufacturers specify efficiency as a percentage, they must indicate whether it's based on HHV or LHV. Most commercial electrolysers use HHV-based efficiency values. Note that efficiency varies with load, though this is often simplified in initial assessments.
-
Capacity Factor: The ratio of actual production to maximum designed production.
Running at 100% capacity is rarely practical due to:
- Electrolyser degradation at maximum load
- Renewable energy source variability
- Maintenance requirements
- System flexibility needs
Typical capacity factors range from 70% to 90%.
Electrolyser Sizing Formula
Electrolyser size (kW) = H₂ demand (kg/day) × 39.44 (kWh/kg) / efficiency / capacity factor / 24
Example Calculation
Using our previous values:
- H₂ demand: 783 kg/day
- Efficiency: 75%
- Capacity factor: 90%
- Required electrolyser size: 1.9 MW
Use our Electrolyser Calculator to determine the optimal size for your project.
Step 4: Calculate Your Compressor Size
Proper compression is essential for hydrogen storage and distribution. The compressor size depends on several factors:
- Required delivery pressure
- Flow rate requirements
- Storage system specifications
- Distribution network requirements
Compressor Sizing Calculator
Use our Compressor Calculator to determine the optimal compressor size for your project. The calculator considers:
- Inlet and outlet pressures
- Flow rate requirements
- Compression ratio
- Efficiency factors
Step 5: Calculate Your Storage Requirements
Storage capacity is crucial for ensuring continuous hydrogen supply. Consider these factors:
- Daily production and consumption patterns
- Buffer requirements for maintenance
- Safety margins
- Storage technology options (gaseous, liquid, or solid state)
Storage Considerations
Different storage methods have varying characteristics:
- Gaseous Storage: Higher volume requirements but simpler technology
- Liquid Storage: Higher energy density but requires cryogenic temperatures
- Solid State Storage: Emerging technology with potential for high density
- Chemical Storage (e.g., Ammonia): Offers high energy density and established infrastructure, though requires additional energy for H₂ recovery
Step 6: Calculate Your Costs
Understanding the economics of your hydrogen project is essential for feasibility assessment. Key cost components include:
- Capital expenditures (CAPEX)
- Operating expenditures (OPEX)
- Energy costs
- Maintenance costs
- Storage and distribution costs
Levelized Cost of Hydrogen (LCOH) Calculator
Use our LCOH Calculator to determine the total cost of hydrogen production, including:
- Electrolyser costs
- Renewable energy costs
- Storage and compression costs
- Operating and maintenance costs
Need Help with Your Pre-Feasibility Study?
Designing a green hydrogen project requires careful consideration of multiple technical and economic factors. We can help you navigate these complexities and optimize your project design.