Does the future of biodiesel lie in algae biodiesel? The algal biodiesel facts are compelling!
As a biodiesel crop biodiesel algae offer amazing yields per acre.
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So is there a catch?
Biodiesel Algae Yields
Biodiesel can be made from almost any organic oil. Currently oilseed (e.g. rapeseed and soy biodiesel) and palm oil are the most
popularly grown biodiesel crops.
In tropical areas, palm oil yields 5 times more per acre – 635 gallons of oil per year.
Unfortunately there are a lot of negative impacts associated with producing these contemporary biodiesel crops.
There must be a better way! And there is…
Studies have shown that the most efficient source of bio diesel oils of all is algae.
With an estimated annual oil yield of 5,000 up to 20,000 gallons per acre in open ponds, producing biodiesel from algae offers productivity advantages that are head and shoulders above even palm oil.
Many commercial applications where algae is grown for biodiesel utilize vertical space by hanging the algae in plastic sleeves.
This both increases the exposure of the algae to sunlight, and thus its productivity, and dramatically shrinks the space needed to grow it.
Making biodiesel from algae has huge implications for the future of biodiesel.
With such an efficient biodiesel crop, biodiesel from algae can offset many of the biodiesel problems inherent in other, less productive bio diesel oils.
• Less land is needed, which means less land is taken away from food production, averting the global starvation that contemporary oilseed biodiesel crops are contributing to.
Similarly, much less land need ever be cleared of forest to grow it.
• Unlike conventional biodiesel crops, the land used for algae biodiesel production does not need to be good agricultural land.
• Unlike conventional crops, the farming inputs are relatively low.
• The algae can be fed on waste. In Permaculture systems it could conceivably be produced as a byproduct of duck or fish production waste waters, or perhaps even using sewerage effluent.
waste gas given off by power station flues,
which they strip of 80% of its pollutants
(chiefly nitrogen oxides and carbon dioxide).
The heat from the flues can even be harvested to dry the algae out ready for the next stage of processing to biodiesel.
Special strains of algae have been developed that grow the right lipid (fat) chains to suit the production of specific fuels – so you can grow jet fuel algae, truck fuel algae and so forth!
How Much Land Would You Need to Make Your Own Algae Biodiesel?
As you can see, growing algae for biodiesel is a pretty exciting concept! It got Graeme and I thinking… How much land would we need to grow a algal biodiesel crop to meet our personal fuel needs?
Here’s what we worked out:
If we used 16 gallons of diesel a week, that’s 832 gallons (3150 litres) a year.
If we achieved 10,000 gallons of algal oil production per acre we’d need 0.0832 acres of open pond to grow it. That’s only 333 square meters (3584 square feet).
Hey, you could fit that on a large suburban block, let alone a small farm! And if you were more efficient, or had a sophisticated vertical sleeve system, you’d need a lot less area to do it.
How An Algae Biodiesel Crop is Grown
Open Pond Systems
This is the cheapest way to grow biodiesel algae.
In open pond algal biodiesel crop systems, the water is circulated around a shallow “race track” trench arrangement using paddle wheels to expose as much algae as possible to sunlight.
Nutrients and carbon dioxide are constantlyfed into the system and algae containing water is regularly harvested for biodiesel production.
There are only a few algae strains that you can grow successfully in open systems because of contamination by and competition from wild algae strains.
One of them is spirulina which not only is a very vigorous algae, but also can grow in alkaline water that is too high in pH for other strains, further reducing competition.
Another disadvantage is that you can’t control the temperature, so that the growing season is limited to the warmer months.
Covered Pond Systems
Enclosing your pond with a greenhouse adds to the expense but also offers advantages that mean even greater productivity and yield than quoted above:
• You can limit contamination by wild algae, allowing a wider range of algae species to be grown.
• You extend the growing season a bit, or a lot if you heat the greenhouse.
• You can increase the amount of carbon dioxide in the system.
Vertical Enclosed Systems
These are highly controlled and highly productive systems. The algae grows in a fully managed environment limited to circulating through connected vertical plastic sleeves with precise carbon dioxide and nutrient levels.
Because there is little danger of contamination, very specialized algae, producing lipids tailored to make particular types of fuels (e.g. suited to aircraft) can be grown successfully.
The system must use a lot of energy for pumping and so forth, but yields a tremendous amount of algal biodiesel from a tiny space.
How Algae Biodiesel is Processed
Basically, you get the biodiesel from algae by first drying it, then pulverizing it, then extracting the oil out of it.
After that, the oil is processed in a theoretically similar way to other organic oils, to break down the viscosity and produce a combustible diesel that will be runny enough to circulate around an engine’s fuel system.
However, algae biodiesel processing is a LOT more complicated for the home biodiesel producer than starting with recycled oils. It's a groundbreaking field that's definitely not for wussies!