HW Assignment: Sustainable Energy
1. Elephant Butte reservoir has a storage volume of 2 million acre-ft of water and an average depth of 65 ft. The net hydraulic head available at this site is 140 ft. The average evaporation rate at this location is 110 in/yr. The design flow rate is 2,000 cu ft/s
Calculate the following:
a. Hydroelectric power potential of Elephant Butte reservoir [in kW]
b. Water loss by evaporation [in Million gal/day]; compare this with the potable water
demand of City of Albuquerque (check on-line).
c. Water loss by evaporation [in gal/kW-hr]; compare this with the general figure
discussed in class.
d. It has been reported that methane emissions from large impoundments can average
1.6 mmoles CH4/sq m per day. Based on this report, estimate the methane
emissions from Elephant Butte reservoir [in tons/day and tons/kW-hr]
e. It has been reported that CO2 emissions from a coal-fired power plant can average
360 gr/kW-hr. Using this report, compare the Elephant Butte reservoir with a
typical coal-fired power plant on the basis of GHG emissions.
f. It has been reported that typical 500 MW coal-fired power plant uses 12 million . gallons of water an hour for cooling. Using this info, compare the Elephant Butte
reservoir with a typical coal-fired power plant in terms of consumptive water use
(gal/kW-hr). Compare your results with the point mentioned in the paper “Greenwashing hydropower”
2. Considering the formula shown in the class for algae, perform the calculations to derive estimates for nitrogen and phosphorous required [lb/day] to produce 100 Million Gal/year of biodiesel. Estimate the footprint of a raceway system to produce the above quantity of biodiesel.
Assume: biodiesel yield = 0.25 gr biodiesel/gr biomass; productivity in a typical raceway = 8 gr/sq m-day.