Total Long Shot - Green Energy - Geothermal, micro hydropower, heat pump?

[trales]

Our furnace has seen its last day. I am thinking of green energy solution rather than another gas furnace.
My options seem to be Geothermal 30K install with 12 year payback - no rebates - but good financing
Heat Pump for outdoor air exchange 12K with 8 year payback - 30% rebate - high electric cost
For electric I could go with a microhydropower system - if (big if) I can get a permit for one on our stream.

New furnace 90+ efficient is $4500. We also only spend $2100 in heat per year (average over 13 years). Small, energy efficient house (75 years old). 1426 sq ft. cape. I keep heat at 52 at night and when gone 62 when home.

We could keep the house 100% of the time at 67. This would also be heating and cooling. The house would be a lot warmer.

To be honest, there are less than 5 days per year we wish we had A.C. Even on the hot days, it still is in the 60's at night. But the house would be a nice even temp year round.

Q's. we love having the windows open when we can. I assume if you are heating and cooling - you can't really keep the windows open all the time. I know the pumps are most efficient when things are consistent.

What do you all think?

[JElaineB]

We got geothermal about 8.5 years ago and totally made the right choice at the time (we had an $800 liquid propane bill for heating for the first December we lived here), but we got a large rebate from the electric company and also the federal tax break was in effect at that time, so we paid much less for our system. We also seriously looked at heat pumps as a lower cost alternative, but for us the geothermal was worth it. We have our hot water hooked into the geothermal as well and get a special electric rate on the electricity the geothermal system requires. We pay between $150-$300/month for all the electricity needed for our 2500 sq foot house (heating/cooling and all appliances included). Given the price difference the heat pump would look very tempting to me in your situation, plus your climate seems a bit milder than ours (we have huge extremes - very cold in winter and can get quite hot in summer). We live on a dusty gravel road so by necessity keep our windows closed all the time, but you are right consistent temps is the most energy efficient way to go. I do however, lower the temp at night and raise it during they day now (didn't do this the first several years but haven't noticed that big a difference in cost/energy consumption). I wouldn't worry too much about that aspect because the times you would keep your windows open are probably the times there is less heating/cooling needed anyway.