One midterm solution that Munich helped pioneer is to have central heating on a large scale. The city's power plant got rid of its cooling pools, and instead pipes the water heated by generating electricity into homes. The city has bee pretty successful in expanding the network so much that the electricity plants have slowly moved from heat being the by-product to electricity being the by-product to the demand for hot water and warm radiators now a driving force. Oh, and it is popular in the city also because it cut down on soot so much.
But that is more of a centralised solution. In your case, the two things you might look into are personal electrical turbines (yes, they are coming on to the market) as well as a modern wood oven. The thing about wood ovens is they are less efficient as wood just isn't that efficient a fuel, but the psychological effect of a wood fire is that it just feels warmer.
The suggestions others make about a water-based solar heating system is also worth noting, as they are really cheap to make yourself. The main issue here is planning, as the water reservoir that you are heating needs space, the pipes have to be laid (though you might be able to use your current radiator network), but it is a good way to at least augment your solution.