My grampa had a pond that was downstream from a dairy farm, and which due to its shape ended up growing these enormous blankets of algae each year. Many a time I had to clear out the ol' fishin' hole by collecting up all the growth so grampa could spread it on the garden, which ended up producing almost more food than his old farm.

So if the first couple years of commercial algae for fuel production ends up as unusable garbage, aren't we still making some killer fertilizer in the process?

The algae, once stripped of oil should make for excellent fodder in concert with the glycerin as cattle are essentially compost systems requiring carbon and protein to make steak etc.

And sadly much of the oil squeezed out of algae is the healthy omega-3 type, which would make for healthier steaks once eaten, but instead makes for a blend of biodiesel useful in northern climates, and more profitable for that purpose than as food.