Reforming has been
around for some time and what makes this interesting is the simple use of
algae, although initial concentration is surely involved as a first step but
that can be a simple centrifuge. One
prefers to minimize the amount of water been used. For the same reason, the output steam is high
grade and can be used to operate a turbine while the spent water can be fed
into a heat exchanger to pre warm the feed stock.
Producing sufficient
feedstock is another matter and hardly a trifle. It requires steady nutrification and ample
CO2 which comes together in certain industrial settings quite well but not
easily otherwise. It is the duckweed
solution again which works just great next to an industrial scaled piggery.
The good news is that
algae based feedstock converts so quickly.
Thus a plant can expected to be easily made small allowing for small
operations. Centrifuged slurry filling
up a feedstock tank is easily acquired and drawing that stock slowly through a heated
pipe is better than a tank cooker. Again
this becomes a more tractable engineering challenge.
Algae to crude oil:
Million-year natural process takes minutes in the lab
December 24, 2013
Engineers at the US Department of Energy’s
Pacific Northwest National Laboratory (PNNL) have created a continuous process that
produces useful crude oil minutes after harvested algae is introduced. This new
process does not require drying out the algae, which grows in water, saving
time and energy that would be otherwise wasted. The final product can be
refined into aviation fuel, diesel, or gasoline.
The process mimics some of the conditions that
originally turned prehistoric plant material into fossil fuel deep within the
earth – high pressures and temperatures.
Algae, an aquatic plant, has long been
considered as a biofuel source, but the steps needed to turn a wet, green plant
into clear, burnable fuel have been both expensive and time-consuming. The
algae had to be processed in a series of steps, one of which involved drying it
out and removing all the water, which might be 80 percent of the biomass. Then
solvents were used to extract energy-rich hydrocarbons from the dried material.
The PNNL team created a continuous process
that starts with the wet algae and subjects the entire mass – water, algae, and
all – to high temperatures and pressures, in this case, 350ºC (662ºF) and 3,000
psi.
"It's a bit like using a pressure cooker,
only the pressures and temperatures we use are much higher," said
Laboratory Fellow Douglas Elliott, the leader of the research team. "In a
sense, we are duplicating the process in the earth that converted algae into
oil over the course of millions of years. We're just doing it much, much
faster."
The products of the process include crude oil,
which can be further refined into aviation fuel, gasoline, or diesel fuel (in
tests, the process achieved between 50 and 70 percent conversion of the
algae’s carbon into fuel); clean water, which can be used to grow more algae;
fuel gas, which can be burned to make electricity or cleaned to make natural
gas; and nutrients like nitrogen, phosphorus, and potassium – needed for
growing algae.
Genifuel Corporation has licensed the process,
and has been working with the team at the lab since 2008. The company intends
to team with some industrial partners to create a pilot plant using this
process to make biofuel in industrial quantities.
The process was detailed in a recent paper
published in the journal Algal Research. More information on
the technology is available in the video below.
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