1.2%这个数字约等于800斤／5.85万斤，我的理解是：方舟子承认钱学森的“30％光照到作物叶子上“和”作物的1／5是粮食“，采用钱学森的结论5.85万斤来计算光合作用效率，因此得到1.2%这个数字。

在这里，你能看到：方舟子错用了5.85万斤这个全年生产作物的数字！如果800斤是海南的产量（袁隆平的试验田就是在海南）还可以理解，但是这是全国的平均亩产，很显然不应该用全年操作的数字。改用3.9万斤来计算，得到的转化率是2%.

Any analysis of biomass energy production must consider the potential efficiency of the processes involved. Although photosynthesis is fundamental to the conversion of solar radiation into stored biomass energy, its theoretically achievable efficiency is limited both by the limited wavelength range applicable to photosynthesis, and the quantum requirements of the photosynthetic process. Only light within the wavelength range of 400 to 700 nm (photosynthetically active radiation, PAR) can be utilized by plants, effectively allowing only 45 % of total solar energy to be utilized for photosynthesis. Furthermore, fixation of one CO2 molecule during photosynthesis, necessitates a quantum requirement of ten (or more), which results in a maximum utilization of only 25% of the PAR absorbed by the photosynthetic system. On the basis of these limitations, the theoretical maximum efficiency of solar energy conversion is approximately 11%. In practice, however, the magnitude of photosynthetic efficiency observed in the field, is further decreased by factors such as poor absorption of sunlight due to its reflection, respiration requirements of photosynthesis and the need for optimal solar radiation levels. The net result being an overall photosynthetic efficiency of between 3 and 6% of total solar radiation.