Sustainable Energy System for Ocean Habitat

WP3 — Energy Subsystem Brief Ocean Habitat Project
Mission Duration: 6 months
Crew Size: 6 people
Location: Offshore, northwest coast of O’ahu, Hawai’i
Coordinates: 21° 34′ 55.81″ N, 158° 20′ 54.29″ W
Water Depth: ~100 m
Ocean Thermal Gradient: ~20.85 °C This brief defines the energy system requirements and loads for the ocean habitat. It includes every bit of data we haveand explains what deliverables are needed from you (the engineer/teammate) for WP3. 1) Project Overview The ocean habitat must be energy-self-sufficient for a 6-month mission with 6 crew members. It must power life support, habitat systems, mission modules (DOC, UDC, DSM), and auxiliary systems using 100% renewable energy and storage. The habitat is located offshore where warm surface water and cold deep water create a ~20.85 °C gradient that can be exploited for Ocean Thermal Energy Conversion (OTEC). OTEC can deliver continuous baseload renewable power because it uses the ocean’s thermal difference to drive a heat engine year-round. 2) Energy Loads & Life Support Requirements 2.1 Habitat & Systems Loads These are the electrical demands for the habitat itself: Component Power (kW) Duty Notes Central Control Unit 1.5 100% Baseline continuous Communications Suite 0.5 20% Intermittent Sensor Network & Alarms 0.2 100% Continuous Robotics Charging Dock 6.0 50% Mission dependent Exterior Lighting 0.8 50% Night/Ops Subtotal ~9.0 — — Safety Margin (+20%) 1.8 — — Total Peak ~10.8–11 kW — ~77 kWh/day This suggests a nominal peak habitat load of ~11 kW with ~2–3 kW continuous requirement. 2.2 Life Support Systems Life support inside the habitat includes air, water, food, and nutrient recycling. These subsystems also require energy: Desalination * Reverse osmosis for freshwater: ~2–3 kWh of electricity per cubic meter of water produced, depending on technology and energy recovery. * Water electrolyzers for hydrogen: ~4–5 kWh per m³ of H₂ produced (the exact amount depends on H₂ volume required). Hydroponic Food Production To meet nutritional requirements of ~2,800–3,000 kcal per person per day using hydroponic systems: * Hydroponics grows ~1.25 kg edible biomass (plus ~0.8 kg inedible) daily per person in vertical racks. * Lighting for optimal plant growth demands ~3500 kWh/year per m² of growing area. * Nutrient cycling systems close N, P, and S loops through biological recovery of organic wastes. These life support loads must be accounted for in your sizing and load tables when designing generation and storage. 2.3 Mission Module Loads Direct Ocean Capture (DOC) * Average power required: 32.82 kW * Equivalent energy per day: ∼787.6 kWh/day This system continuously extracts CO₂ from seawater. Underwater Data Center (UDC) Parameter Value IT Load 100 kW Parasitic cooling/pumps ~7.5 kW Total UDC Load ~104 kW Daily energy ~2,496 kWh/day Waste heat available for recovery ~40 kW (~960 kWh/day) This high continuous load must be supported by generation and storage capacity. Deep Sea Mining (DSM) DSM is mission-dependent and has high peak loads: System Power (kW) Pumps 250 Filtration 150 Docking systems 50 Maintenance robotics 100 Lighting/control 50 Total ~600 kW Daily (if fully active) ~14.4 MWh/day Because DSM loads will vary with mission activity, your design must consider peak vs average consumption. 3) Renewable Generation Mix Requirements The energy system must integrate multiple renewable sources: A) Ocean Thermal Energy Conversion (OTEC) OTEC uses the temperature difference between warm surface ocean waters and cold deep water to produce electricity continuously using a heat engine (typically closed-cycle). This makes OTEC particularly suitable for baseload power at tropical sites like Hawaii where the thermal gradient exceeds ~20 °C. Role: Continuous baseload generation. B) Wave Energy Wave energy converters capture energy from the motion of waves to produce supplemental electricity. Hawaii’s consistent wave climate makes wave energy a viable complementary source to OTEC and solar. C) Floating Solar Photovoltaics (PV) Solar panels mounted on floating platforms generate electricity during daylight hours and help charge storage systems (batteries and/or hydrogen production) for use when generation is low. 4) Storage & Distribution Requirements Because wave and solar are intermittent, and OTEC output may fluctuate with water conditions and system dynamics, energy storage is required to ensure power is always available. Storage Options * Battery Energy Storage System (BESS):
Provides short-duration storage (minutes to hours) to smooth generation variability and handle load spikes. * Hydrogen Storage:
Excess renewable electricity is used to produce hydrogen via electrolysis; hydrogen is then stored and converted back to electricity via fuel cells when needed. This system is necessary for long-duration backup (days of low generation) and emergency resilience. Your deliverables must include storage sizing calculations for both battery and hydrogen systems to survive storms or extended low renewable output (worst-case scenarios). Microgrid Architecture You must define the distribution system with: * Voltage levels (e.g., main AC bus voltage) * Redundancy (e.g., N+1 paths) * Load shedding strategy that prioritizes critical systems like life support and habitat control when energy is limited. 5) Thermal Integration Waste heat from the UDC cooling systems, OTEC, and other equipment must be managed using the ocean cold sink(pumping cold deep water) and integrated into habitat systems where beneficial (e.g., desalination pre-heating, hot water systems). Heat recovery strategies should be described and accounted for in energy balance calculations. 6) Required Deliverables You must produce the following items clearly and professionally: Deliverable 1 — Objective Tree Create a hierarchical objective tree showing WP3 energy goals: * Primary goal: Provide continuous renewable energy for all loads. * Secondary goals: Baseline generation, storage resilience, redundancy, thermal management, and load control. Deliverable 2 — Requirements Specification Table Build a table listing: Requirement number Description Requirement  Type Rationale Traceability to objective tree Deliverable 3 — Functional Flow Chart Produce a one-line power flow diagram illustrating: * Renewable generation systems (OTEC, wave, floating solar) * Storage systems (BESS, hydrogen production & fuel cells) * Microgrid main bus and distribution lines * Interfaces to loads (habitat systems, DOC, UDC, DSM) * Redundancy paths and load shedding points Deliverable 4 — Calculations & Sizing Provide detailed calculations for: * Sizing each generation type based on site resource data (thermal gradient, wave climate, solar irradiance) * Storage capacities for BESS and hydrogen to support continuous operation and emergency scenarios * Microgrid architecture (voltage levels, redundancy, and protection) * Load matching — show generation vs demand balance over time (average and peak) * Worst-case scenario analysis (e.g., storm or multi-day low generation period) Deliverable 5 — Thermal Integration Analysis Explain how waste heat is rejected and reused: * Cold sink utilization * Recovered heat used in habitat subsystems * Overall thermal balance and efficiency improvements

N° de projet : 40242003