Question

A community of 2,500 homes is considering their options for generating electricity locally. The final three options under consideration are:

• A river which runs to the north of the community, which is suitable for the installation of a hydroelectric generation facility.
• A large flat-topped hill to the east of the community, which could be used for a wind farm.
• Open land to the south of the community, which could also be used for a wind farm.

The residents of the community have already discounted the possibility of a solar farm, as the amount of sunlight at this location is lower than the UK national average.

• .The hydroelectric facility that has been proposed will consist of a turbine with an efficiency of 86.0%. The facility will be located at a vertical depth of 12.0 m below the river bed. The river flows with the following properties:
  • hydraulic diameter of 5.80 m;
  • slope of 0.030
  • wetted perimeter of 11.0 m;
  • a Chézy coefficient of 5.00 m^0.5 s⁻¹.

The density of the river water is 998.2 kg m^-3, and the acceleration due to gravity is 9.81 m s^-2.Assume that the turbine operates for 95.0% of the time, and that 1 year is approximately 3.1536 × 10⁷ s.

• it is proposed that three-blade type wind turbines are installed, which can generate electricity for a wind velocity range from 3.00 m s^-1 to 12.0 m s^-1.

The turbine blades are 70.0 m in length, the power coefficient is 0.520 and the average air density is 1.21 kg m^-3.

Site WT1 can accommodate 3 wind turbines, whereas site WT2 can accommodate 5 wind turbines. It is estimated that the turbines can operate for 80.0% of the time at site WT1, and 85.0% of the time at site WT2.

QUESTION:

a.Assume that each home has an average energy demand of 3,700 kWh per year. Determine the percentage of the energy supply from each of the generating options (hydroelectric, wind WT1 or wind WT2) that the average energy demand of the community represents.

• b.Describe which option you would recommend to the community. Justify your decision, discussing the benefits and drawbacks associated with each of the three options available.

Answer 1