How many pounds of coal must be burned to keep one 100-W light bulb lit for one

Question

How many pounds of coal must be burned to keep one 100-W light bulb lit for one hour? Assume the efficiency of the power plant is 35%. the transmission losses are 10% of the delivered power, and the heating value of coal is 12,000 BTU/lb. A nuclear-power station with a life of 25 yr produces 750 MW/yr as useful energy. The energy cost is as follows: 150 MW lost in distribution 20 MW needed to mine the fuel 50 MW needed to enrich the fuel 80 MW (spread over 25 yr) to build the plant 290 MW lost as heat What is the efficiency of the plant? What is the efficiency of the system (including distribution losses)?

Explanation / Answer

7.1 BTU provides 1055.055 J W = J/S Transmission efficiency = 1 - 0.1 = 0.9 100W over an hour is 100J/S * 3600S = 360 KJ To deliver 360 KJ, the power plant must produce 360 KJ / (0.9 * 0.35) = 1142.86 KJ Pounds of coal X 12000 BTU/lb X 1055.055 J/BTU = 1142.86 KJ coal = 0.09 lbs 7.3 Energy produced: 750 MW Energy lost in production due to heat: 250 MW Efficiency = (750-250)/750 = 67% Energy cost of system: 150 + 20 + 50 + (80/25) + 290 = 513.2 MW Efficiency = (750-513.2)/750 = 31.6%

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.