The Clinton Administration's fiscal year 1999 budget marks a revival o
f interest in using the federal income tax Code to influence energy de
mand. In the 1970s, Congress enacted tax incentives for energy conserv
ation and alternative fuels. Now, the threat of global warming has aga
in focused attention on energy use. This paper evaluates the proposed
federal tax incentives to mitigate global warming, concluding that mos
t of the government's funding for energy conservation, alternative fue
ls, and other global warming mitigation related expenditures is throug
h the tax Code, rather than direct spending programs. The tax incentiv
es in the Administration's budget proposal are best viewed as demonstr
ation projects designed to provide information about the commercial po
tential of certain technologies, not a least cost method of reducing g
reenhouse gas emissions.