Apparently it can be as low as 50mA maximum now [0]. However bear in mind this is the maximum speed. For a low power sensor, you could bring the clock speed down a lot lower to reduce consumption on writes. It's also unlikely you will be writing 40MB/s constantly :)

[0] http://www.swissbit.com/images/stories/pdfs/S-300u_data_shee... (page 8).