Carbon Debt and Carbon Payback time have recently been introduced into the Norwegian debate on greenhouse gas emissions, challenging the established view that Biofuels are carbon neutral. This report demonstrates that these new concepts are primarily a reflection of how the temporal system boundaries for CO2 emissions from biofuels are viewed. In a short term perspective it is possible that CO2 emissions from biofuels may have a non-zero short term climate effect, even though biofuels will be carbon neutral on the order of a century. Two alternative, more useful new concepts for analysis of climate effects of biofuels are described in this report: The Global Warming Potential (GWP) index for biofuels and the Albedo effect. In particular, one should be aware that the Albedo effect may overshadow the effects of CO2 emissions from biofuels. Finally, the report describes how waste incineration based District Heating systems may have greenhouse gas emissions on the same order as natural gas.