We just received our "jaarafrekening". This is the final yearly invoice sent by our energy company. They are about to pay us €252, and we will continue to pay them €5 per month next year, just like last year. i.e. overall our energy company is paying us about €200 for last year's electricity. Everything in our home is powered by electricity. No gas connection. No wood burner.
Nothing that we've done to achieve a negative energy bill was especially expensive. In particular, our installation of a air-air heat pump and a couple of extra solar panels cost far less than several of our neighbours paid for the wood burning stoves they've installed, which stink up the neighbourhood all through winter.
We also don't have to buy wood to burn.
People concerned about the cost of heating with gas buy woodburners at a higher rate than heat pumps largely because they have no idea about the relative costs. If they knew, perhaps we could have clean air.
I'll write a comprehensive blog post at the end of March about energy consumption, costs & emissions due to the heatpump vs. gas this winter. I can tell you already that we using a lot less total energy now.
To summarise: In the worst case, our CO2 emissions are reduced by 95% vs. burning gas, we have no heating bill at all any more, and our home was warmer than before.