Tuesday, April 19, 2005

Widescale Biodiesel Production from Algae

With the Oil Peak upon us, there's a need to find a way to run our society without being beholden to Fossil Fuel and its attendant dependence on OPEC. While I personally prefer electric vehicles, I also see a different solution as being very exciting.

Biodiesel is a liquid fuel that is highly compatible with the existing infrastructure. Instead of digging up fossilized oil from zillions of years ago, it takes plant material growing today and through industrial chemical magic extracts the oil. Uhm, remember that you probably have several bottles of oil derived from vegetable material already in your house. Ergo, Olive Oil, Canola Oil, or even (urgh) Crisco, all are oil products derived from plant material. With a little bit of simple processing you can take that oil, and create a diesel fuel that will easily cause your car to move down the street.

Enter, this proposal:

Widescale Biodiesel Production from Algae

The Office of Fuels Development, a division of the Department of Energy, funded a program from 1978 through 1996 under the National Renewable Energy Laboratory known as the "Aquatic Species Program". The focus of this program was to investigate high-oil algaes that could be grown specifically for the purpose of wide scale biodiesel production1. The research began as a project looking into using quick-growing algae to sequester carbon in CO2 emissions from coal power plants. Noticing that some algae have very high oil content, the project shifted its focus to growing algae for another purpose - producing biodiesel. Some species of algae are ideally suited to biodiesel production due to their high oil content (some well over 50% oil), and extremely fast growth rates. From the results of the Aquatic Species Program2, algae farms would let us supply enough biodiesel to completely replace petroleum as a transportation fuel in the US (as well as its other main use - home heating oil) - but we first have to solve a few of the problems they encountered along the way.

The article is written by Michael Briggs, University of New Hampshire, Physics Department. He goes over the use of specific algae species to produce oil, and to convert that oil to biodiesel.

He notes that current U.S. consumption of gasoline is 120 billion gallons per year, and consumption of petroleum diesel is 60 billion gallons per year, 180 billion gallons total. However biodiesel, gasoline, and petroleum diesel, are not all exactly equivalent, so he does some calculations to show that replacing U.S. fossil fuel usage with biodiesel would require 138 billion gallons per year.

That's actually quite a large chunk of fuel to produce per year. Think Wesson can handle it? Are there enough Olive trees around?

This is where the algae comes in. One would grow algae in ponds, harvest it, and extract the oil. NREL worked out the process and also production capacities.

Based on the NREL study, he shows it would take 15,000 square miles of algae ponds to produce enough biodiesel fuel to power current U.S. needs. While that might seem like a big chunk of land, it is an area only 15% the size of the Sonora desert. There is a lot of empty land out west. Though, actually, I can't imagine a water intensive industry like growing algae would work well in such a water starved place as the U.S. West.

As Dr. Briggs notes it would be best to site these plants around the country. For example they could use existing waste streams as a food source, perhaps assisting with breakdown of municipal or farm "waste" products into a more benign substance. This is already a known field, namely biodigesting. For example Fuel Cell Energy, a maker of fuel cells that can run on methane, has made several sales to corporations with existing waste streams, who are reusing the waste streams to produce methane used in running the fuel cell that provides the electricity to run their factories.

Additionally there are other byproducts that could be used in creating fertilizers.

The operating costs (including power consumption, labor, chemicals, and fixed capital costs (taxes, maintenance, insurance, depreciation, and return on investment) worked out to $12,000 per hectare. That would equate to $46.2 billion per year for all the algae farms, to yield all the oil feedstock necessary for the entire country. Compare that to the $100-150 billion the US spends each year just on purchasing crude oil from foreign countries, with all of that money leaving the US economy.

Let's go over this a little more slowly.

First, the 15,000 square miles is actually 3.85 million hectares, just viewed with a different unit of measurement.

Next, he calculates a cost of running such algae farms. You can think of that as the cost of the raw material, and by the time the material reaches consumers in the form of biodiesel it might be $150 billion worth of product (depending on the profiteering along the way).

Third, he points to the amount the U.S. spends to buy the oil we need to run the economy. The $100-150 billion per year is the amount sent to foreign countries to buy oil from them. Hence his comment about this being money leaving the U.S. economy. That amount of money degrades the U.S. balance of trade, meaning we have U.S. capital leaving this country.

Of course the money is not the only cost. There is an energy budget to consider. Does it require more energy to produce this biodiesel, than the energy you get upon burning the biodiesel. I don't know the answer, however many of the processes he's talking about here occur with the help of the Sun's energy. Algae is a form of solar power, using photosynthesis to do its magic. This means that for much of the "product cycle" we can sit back and let the algae do its work, without using some machine that requires power.

In the paper Dr. Briggs uses the term "Energy Return on Investment" to describe this. You're going to spend some energy on operating a process that produces energy in another form. If you spend more energy than you get as a result, then you've wasted your time and squandered your energy.


allvoices