Wednesday, October 13, 2010

Algae to Fuels Under Pressure.

The conventional route to biodiesel consists of extracting oil from plants and converting it to the methyl esters of fatty acids that are present in the lipid-components, known as triglycerides. These esters as a mixture constitute biodiesel: a specific kind of biofuel. High oil-yielding strains of algae can be grown and dried and the oil extracted from the dry algal mass, before being similarly converted to biodiesel in a process called transesterification.

Removing the water from raw algae is a highly energy intensive process, and to minimise the overall energy costs of biofuel production from algae, a process called hydrothermal liquefaction may instead be employed in which the algae are not dried but heated under pressure such that the water they contain acts as a chemical reagent and solvent that breaks-down the algal cells and converts not only the oil (lipid) but the sugar and protein component into fuels such as liquid hydrocarbons, gaseous fuels like methane and a complex material called "bio-oil" with a similar energy content to crude oil.

Clearly, the design of engines will need to be adapted in order to use these alternative fuels directly, or they must be refined in a "biorefinery" along with those from other kinds of biomass. In both cases of new engines or biorefineries, there will be huge new engineering required and on a scale that can only be guessed at if really algae can be exploited to make a nation the size of the United States independent of cheap imported crude oil.

Nonetheless, there is a consortium (National Algae Association) in the U.S. that is actively seeking a future in which algae are grown on a large scale and converted to oil-alternative fuels. Certainly, it is likely that algae will become an essential component of the mix of means to keep transportation going by means other than crude oil.

The claims of the NAA are undoubtedly true, that ultimately the supply of petroleum must decline, oil prices will continue to be volatile with knife-edge consequences for the world economy, and a wholesale industry based on algae would provide precious and needed jobs and economic development in the U.S. The approach could be introduced on necessary levels for all nations and even a village "pressure cooker" to provide algal fuels for small communities.

Related Reading.
A. Demirbas, "Use of algae as biofuel sources," Energy Conversion and Management, 2010, 51, 2738-2749.


Mark said...


This is a little off topic but I would like to get your opinion on this. By all appearances it seems that the Western United States is fast headed if not already experiencing peak fresh water. Water supplies to the farmers in the san joaquin valley have been greatly curtailed which is causing great economic distress and the levels of the Hoover Dam are dropping at such a fast rate that there is the possibility of its hydroelectric turbines being shut off by 2013. In Monterey each household is now limited to 40 gallons of water per person per day.

In response to our water crisis there is a building boom of desalination plants on the coast of California, some of which are not too far from where I live. There is opposition to these plants but I think by the end of the day they will be built because the need water is just too great.

Cities such as Phoenix, Las Vegas and Los Angeles depended on the supply of cheap water to fuel their growth. If this cheap supply is cut off and water is rationed what will happen to our great cities in the desert? Could technology, such as desalination and water reclamation be our savior or are they like giving a band aid to a patient with terminal cancer?

Professor Chris Rhodes said...

Hi Mark,

I am aware that there is a freshwater problem in the US (among other places). 40 gallons (US) or 150 litres is typical for a western water use, compared to a few litres in rural Africa for example!

I think all of this is a matter of keeping the tide (so to speak) at bay, and that yes, desalination plants will be useful. They are highly energy thirsty though. There is one to be build near the mouth of the Thames to provide water for London; well presuming the government spending review doesn't cause that to be axed next week (20th).

So, in summary I think DS plants and water reclamation will help prolong the status quo, but as with the oil supply, eventually liberal amounts of water will prove a thing of the past.

We are using too much water and energy because there a are too many of us living at a very high standard, which is unsustainable.

Either with what we have or these stop-gap measures, we need to plan to live with less.

That is the only solution I can envisage but I can't visualize that necessary transition.



Elrond Hubbard said...

Hi Chris, I've just found your excellent blog.

Regarding the challenge of extracting oil from algae, I'm wondering what you think of the single-step extraction, and live extraction techniques by Origin Oil, an algae company located in Los Angeles, USA.

I guess we can't tell how feasible this is from reading the company web page, but their technology is being implemented for carbon capture from power plants in Australia in conjunction with MBD energy, and within a year or two we might see what the results are.

Professor Chris Rhodes said...

Hi Elrond,

I must say, that video of the algae being broken down by the EM fields looks amazing... the cell detritus simply falls to the bottom as "biomass" while the oil floats on the top.

I wonder how much energy is required to run this one-step unit and how much resource/time etc. would be required to get the technology up on the grand scale? Probably a lot on all counts.

It is impressive though.