Marine Bioenergy
Economic Systems Analyses for Novel
Marine Energy Production Strategies
James Burgess
Mark Smith
Babur Khwaja
MAT ‘09
EEB ‘09
ECO ‘09
Motivation
 Food:
Ocean production facilitates
scalability, without interference in food markets.
 Climate:
Provides opportunities for Carbonneutral or Carbon-negative energy production
based on fixation of atmospheric CO2
 Efficiency:
Rapid, continuous growth rates
outperform terrestrial crops in primary
productivity
Technical Considerations
 Species Selection
 Micro-algae vs. Macro-algae
 Benthic vs. Pelagic
 Production Method
 Terrestrial vs. Ocean based
 Nutrient delivery
 Conversion Method
 Biochemical vs. Thermochemical
 Desired energy product
Previous Efforts
 Focus on microalgae for lipid production
 Pros:
 Easy to Culture
 Easier genetic manipulation
 More valuable energy product
 Cons:
 Harvest Cost
 Cost of Containment
Our Strategy
 Focus on production cost reduction
rather than product value
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Avoid centrifugation/floculation costs
Avoid engineering cost of growth container
Utilize waste stream as nutrient source
Accept low product value of macroalgae
System Architecture
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Select Feedstock
Implies Production Method
Nutrient Provision from Sludge
Harvesting by Kelp Mowers
Digestion into Biogas
Biogas Cleanup and Distribution
Experimental Program
 Empirically test key assumption of
feasibility of sludge application
 Sludge from Hightstown bio-digester
 Difficulties in establishing Sargassum culture
 Decision Point: replace with reasoning
from literature analogy
Results
 Best Case: Sargassum  Ocean Production 
Biogas Production with Electricity Cogeneration
 System highly dependent on revenue from
sewage sludge tipping fees
 Resultant limit on scalability
 Scales to waste market
Relationship Between Sludge Tipping
Fee and NPV
Maximum Scalability
NPV ($ Million)
150
100
50
~ 1%
Gross US Energy
~ 4%
US Natural Gas
0
0
5
10
15
20
25
30
-50
-100
Sludge Tipping Fee ($/tonne)
Assumes 10,000 hectare farm, $30 carbon tax
Key Parameters

Systematic sensitivity analysis yields
following rank order of parameter
importance
1.
2.
3.
4.
5.
Sludge Tipping Fee
Farm Size
Harvest Cost
Methane Production Rate
Carbon Tax
Conclusions
 Our research supports the finding that
Sargassum cultivation for biomethane
production could be viable given:
 Moderate sewage sludge tipping fees
 Dramatic cost reduction in harvesting system
 Higher methane conversion efficiencies
 We conclude that this project is not currently
worth pursuing further due to the difficulty of
meeting the above conditions
Thank You!
 Key Advisors and Mentors
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Tom Kreutz
Nick Bennette
Damian Carrieri
Chuck Dismukes
Steve Pacala
 Funding Support
 PEI
 EEB Department
 Explorer’s Club
Questions?