Just answer questions e and f

(a)

1 therm = 29.30 KWh

Hence,

Gas storage: 191 therm

Gas tankless: 209 therm

Electric storage: 3493 KWh = 119.21 therm

Electric heat pump: 915 KWh = 31.22 therm

Therefore, electric heat pump consumes the least energy.

(b)

Gas storage: 439+37.32+600 = 1076.32

Gas tankless: 898+76.33+1300= 2274.33

Electric storage: 359+30.52+500= 889.52

Electric heat pump: 1299+110.42+500=1909.42

(c)

Gas storage: 191 0.1 17 = 324.7

Gas tankless: 209 0.1 17= 355.3

Electric storage: 3493 0.12 = 419.16

Electric heat pump: 915 0.12 = 109.8

(d)

Gas storage: 1076.32 +15 (324.7) = 5946.82

Gas tankless: 2274.33 + 15(355.3) =7603.83

Electric storage: 889.52 + 15(419.16)= 7176.92

Electric heat pump: 915 + 15(109.8)= 3556.42

My water heater is a traditional one that heats water with natural gas and keeps it in a big insulated tank ready to use this is known as a "storage water heater). The Energy Guide sticker estimates an annual energy use of 254 therms of natural gas per year. I'm considering replacing it. I'm considering four options: (1) Natural gas storage: A standard gas heater that's just newer and more efficient than what I currently have. (2) Natural gas tankless: Tankless systems heat water on demand instead of keeping a big tank hot around the clock. (3) Electric storage: This is an electric version of a storage water heater. (4) Electric heat pump storage: Also known as a hybrid water heater, this is a newer design that draws on ambient room heat to keep the water warm. Here's what Home Depot lists as their current price and annual energy usage. Note that I chose relatively energy efficient options for each type of technology 2 3 Gas storage Gas tankless Electric storage Electric heat pump Purchase price $898 $359 $1,299 Annual energy use 191 therms 209 therms 3493 kWh 915 kWh $439 (a) Lowest energy? Which option uses the least energy over the year? 4 points (b) Capital costs: CapEx includes the purchase price, 8.5% sales tax, and installation costs. Assume that Option 1 costs $600 to install, Option 2 costs $1300 to install, and Options 3-4 costs $500 to install. What's the CapEx for each option? 8 pts (c) Annual operating costs: Assume that electricity costs $0.12/kWh and natural gas costs $17 per thousand cubic feet (tcf). What's the annual OpEx for each option? (Hint: 1 therm = 100,000 Btu = 100 cubic feet) 6 pts (d) Lifetime costs: Water heaters last 15 years. What are the lifetime costs (CapEx + OpEx) of each option? (Note: the one with the highest price tag ends up saving money in the long term. This shows you that you can't just look at the Capex!) 4 pts (e) Payback time if you compare the two electric options: What's the payback time of the electric heat pump compared to the conventional electric storage (Opt 4 versus Opt 3)? Answer in years to two decimal places. 8 pts (1) Payback time if you compare to my existing water heater: I also have what we might call Option 0, which is continuing to use my current heater. What's the payback time of the electric heat pump compared to my existing water heater, which uses 254 therms per year? Answer in years to two decimal places. 8 pts (9) Conservation: Without replacing the water heater, what are three conservation actions that I could take now to reduce my hot water energy? You can just list them. 6 pts Problem 3: Water Heaters (a) You'll have to reason your way through this one. (b) Option 1: $1,076.32 Option 2: $2,274.33 Option 3: $889.52 Option 4: $1,909.42 (c) Option 1: $324.70/year Option 2: $355.3/year Option 3: $419.16/year Option 4: $109.80/year (d) Option 1: $5,946.82 Option 2: $7,603.83 Option 3: $7,176.92 Option 4: $3,556.42 (e) 3.29 years (1) 5.92 years (g) Your answers will vary