ocean energy

SUSTAINABLE ENERGY: ENGINEERING FUNDAMENTALS AND APPLICATIONS - OCEAN ENERGY

The oceans harbor various forms of energy under the term ocean energy, also known as marine energy or marine and hydrokinetic energy.
Ocean energy can be harnessed through the following types:
- Kinetic Energy: Derived from the movement of water, such as tides and waves.
- Potential Energy: Energy stored due to the water's position, particularly in tidal systems.
- Thermal Energy: Energy associated with temperature differences in ocean water.
- Osmotic Energy: Harnessed from the salinity gradient between freshwater and seawater.
Kinetic and Potential energies can be sourced from tides and waves, while thermal energy is harnessed using systems like Ocean Thermal Energy Conversion (OTEC).

Tidal energy can be classified into:
- Tidal Barrages: Technologies converting potential energy to electricity.
- Tidal Streams: Technologies converting kinetic energy from moving water.
Wave energy technologies can convert both kinetic and potential energy into mechanical and electrical energy.

OTEC utilizes the temperature gradient in oceans for energy generation and water desalination.
Three configurations exist:
- Open-Cycle OTEC:
- Generates electricity from steam produced from surface ocean water.
- Involves flash evaporation—controlled evaporation under low pressure facilitated by a vacuum pump.
- Closed-Cycle OTEC:
- Employs a working fluid with a low boiling point (e.g., propane, ammonia) based on the Rankine cycle.
- Hybrid OTEC:
- Combines features of both open and closed cycles, producing drinking water while maximizing energy output.

Salinity Gradient Energy: Energy created when freshwater and seawater meet, potentially in a halocline.
Methods for electricity generation from salinity gradients include:
- Pressure-Retarded Osmosis (PRO): Osmotic pressure is harnessed as freshwater permeates through a semipermeable membrane.
- Reverse Electrodialysis (RED): Electricity is generated directly from the chemical potential difference between saltwater and freshwater without mechanical energy conversion.

Visual representation of global ocean energy deployment capacities showcases technologies utilized.
Breakdown of ocean energy capacities per country includes official, unofficial, and estimated data.
Small Island Developing States (SIDS) heavily invest in ocean energy due to their blue economy potential.

Total cost of deploying ocean energy technologies consists of:
- Capital Costs: Feasibility analysis, design, construction, infrastructure, and commissioning.
- Operational Costs: Involves wages, utilities, maintenance, and insurance.
Ocean energy technologies generally exhibit higher Levelized Cost of Energy (LCOE) compared to other renewables.
Enhancements in marine energy technology and synergistic deployment with wind/solar are expected to reduce risks and overall costs.

Ocean energy encompasses various forms, including tidal, thermal, salinity gradient, and wave energy.
Technologies convert these energy forms into electrical power, requiring an understanding of key principles in thermodynamics, fluid mechanics, and fluid dynamics.
Tidal energy varies globally and is reliant on the gravitational effects of the moon and sun, providing predictable generation potentials.
The economic impact is significant with ongoing developments aimed at making ocean-energy solutions more cost-effective.

Osmotic Pressure Formula:
egin{equation} \ ext{Osmotic Pressure} ( ext{π}) = i R T M \ ext{(Equation 10.13)} \ ext{where:} \ i = ext{van’t Hoff factor} \ R = ext{universal gas constant} \ T = ext{absolute temperature} \ M = ext{molar concentration} \ \ ext{Pressure Calculation} \ p = \frac{W}{A} = \frac{mg}{A} = \frac{\rho V g}{A} = \rho g h \ ext{(Equation 10.14)}\
Tidal Energy Equation:
- Potential Energy for Tides:
  egin{equation} E{cycle} = \frac{1}{2} A \rho g R^2 ext{ (Equation 10.17)} \ \text{Daily Energy Production: } E{day} = \frac{24 ext{ hours}}{12.4 ext{ hours}} * E_{cycle} ext{ (Equation 10.18)} \end{equation}