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A growing body of evidence suggests that the solar wind is powered to a largeextent by an Alfv\'en-wave (AW) energy flux. AWs energize the solar wind viatwo mechanisms: heating and work. We use high-resolution direct numericalsimulations of reflection-driven AW turbulence (RDAWT) in a fast-solar-windstream emanating from a coronal hole to investigate both mechanisms. Inparticular, we compute the fraction of the AW power at the coronal base($P_{\rm AWb}$) that is transferred to solar-wind particles via heating betweenthe coronal base and heliocentric distance $r$, which we denote $\chi_{\rmH}(r)$, and the fraction that is transferred via work, which we denote$\chi_{\rm W}(r)$. We find that $\chi_{\rm W}(r_{\rm A})$ ranges from 0.15 to0.3, where $r_{\rm A}$ is the Alfv\'en critical point. This value is smallcompared to~one because the Alfv\'en speed $v_{\rm A} $ exceeds the outflowvelocity $U$ at $r<r_{\rm A}$, so the AWs race through the plasma without doingmuch work. At $r>r_{\rm A}$, where $v_{\rm A} < U$, the AWs are in anapproximate sense "stuck to the plasma", which helps them do pressure work asthe plasma expands. However, much of the AW power has dissipated by the timethe AWs reach $r=r_{\rm A}$, so the total rate at which AWs do work on theplasma at $r>r_{\rm A}$ is a modest fraction of $P_{\rm AWb}$. We find thatheating is more effective than work at $r<r_{\rm A}$, with $\chi_{\rm H}(r_{\rmA})$ ranging from 0.5 to 0.7. The reason that $\chi_{\rm H} \geq 0.5$ in oursimulations is that an appreciable fraction of the local AW power dissipateswithin each Alfv\'en-speed scale height in RDAWT, and there are a fewAlfv\'en-speed scale heights between the coronal base and $r_{\rm A}$.

How Alfv\'en waves energize the solar wind: heat vs work