That's one possibility. Our boiler is wired to a small, fuel efficient gas generator and whilst a diesel set would be nice, this low-cost solution has served us well thus far. Under normal circumstances, the bulk of our space heating needs are met by the ductless heat pumps with the boiler providing additional support when temperatures fall below -15C or -20C (there's some electric in-floor radiant heat as well, but it's seldom used).

With the aid of the generator, the boiler and indirect water heater are our primary source of heat and domestic hot water during extended power outages. I keep a minimum of 500-litres of heating oil on hand at all times and enough gasoline to fuel the generator for two to three months, assuming one to two hours use per day; that should be sufficient to bump up temperatures so that the pipes don't free. If the generator should break down or we exhaust our fuel reserves, there are four propane fireplaces that can used for spot heating. Propane is the fuel of last resort, as it would be used for cooking purposes as well (we try to keep the main tank topped up and a couple BBQ tanks as spares).

We've also worked hard to reduce our space heating requirements so that a larger percentage of our needs can be met through passive solar; over the past seven years, we've cut our home's energy usage by over 90 per cent -- whereas the previous home owners used 5,700 litres of fuel oil and 14,000 kWh of electricity per year, we're now down to 350 litres and 12,000 kWh, plus some 50 to 70 litres of propane (the latter mostly for clothes drying and the BBQ). This has reduced our household expenses considerably and, most importantly, allows us to stretch our fuel supplies to the greatest extent possible should the need arise.

Cheers,
Paul