$${\begin{align*}P_\text{Al} &\approx \mathrm{(5,67 \times 10^{-8}\, W/m^2 \cdot K^4)(0,03)\times \\ \times(0,016\, \mathrm{m^2})[(363\,K)^4 - (293\, K)^4]} \\&= 0,27\, \mathrm{W} \end{align*}}$$