49 



For the past 5 or 6 years I have been conducting experiments 

 along these Unes in Florida at the Harbor Branch Foundation, a 

 small private laboratory, working both with freshwater weeds, like 

 water hyacinths, duckweeds, and so forth, and also with seaweeds. 



When the Department of Energy "fuels from biomass" program 

 then started up I found out about this and was able to get some 

 support to look at the possible use of seaweeds and fresh water 

 weeds as a biomass source for energy. 



So I would like to talk a little bit about my experience there but 

 try to put it first in some perspective and then begin perhaps 

 considering some of the problems of biomass production on land in 

 the terrestrial environment. 



And it seems to me that there are two major problems with this. 

 One of them is the tremendous land requirement for this. Consider- 

 ing, for example, trees for burning wood, which seems to be the 

 most promising aspect of the fuels from biomass program at the 

 moment. There is nothing new or startling about it. It has been 

 going on for a long time but it does seem that renewed efforts in 

 this area may prove profitable and there are new technologies for 

 growing trees for this purpose. 



Short rotation crops that can be cut off and the new trees will 

 grow up from the roots. They are projecting yields and have, I 

 guess, experimentally found yields of as high as 10 dry tons per 

 acre per year from this. This dry wood is very high in its energy 

 content, 30 million Btu's per ton or so. 



In spite of these high yields and high energy content, to get a 

 quad of energy from wood, if you were going to use it to generate 

 steam in a conventional powerplant, it would take about 10 million 

 acres — 15,000 square miles, that is. It is a pretty sizable piece of 

 real estate. 



Other forms of terrestrial biomass, like sugar, which has been 

 talked about today, that is certainly the most productive terrestrial 

 crop in the world actually. In the continental United States the 

 yields are a little lower than they are in places like Hawaii, but 

 they average about 10 tons dry weight per acre per year. 



If you were going to ferment that and make ethanol out of it, 

 gasohol, again, it would take 44 million acres for 1 quad of energy. 

 There aren't many places in the mainland United States where you 

 can grow sugar. 



The average production of terrestrial vegetation on land is about 

 1 ton per acre per year. That is agricultural crops and grazing 

 grassland. According to the Department of Energy, this is about 1.2 

 billion tons produced over 1 billion acres of cultivated land. 



That is not a very high yield, 1 ton per acre. If you fermented 

 this and made methane out of it, which is perhaps the only thing 

 you can do with most of these terrestrial that are essentially wet 

 biomass, if you ferment it, which is also an inefficient system, it 

 would take something like 200 million acres to produce 1 quad of 

 energy. That is 10 percent of the area of the United States. 



This is somewhat unrealistic, it seems to me, to be thinking 

 about producing large quantities of fuel on land. 



The other big constraint is the economic one. All of the best land 

 available for this purpose is already in use for agriculture for food 

 and fiber crops, and these are generally worth 10 to 100 times as 



