Content uploaded by Scott C. James
Author content
All content in this area was uploaded by Scott C. James on Jan 17, 2019
Content may be subject to copyright.
Content uploaded by Jim Stewart
Author content
All content in this area was uploaded by Jim Stewart on Sep 19, 2018
Content may be subject to copyright.
1
Ocean Forests: Breakthrough Yields for Macroalgae
Mark E. Capron, PE
OceanForesters
Ventura, CA, USA
MarkCapron@oceanforesters.org
Reginald Blaylock, PhD
Thad Cochran Marine Aquaculture Center, School of Ocean Science
and Engineering
University of Southern Mississippi
Ocean Springs, MS, USA
Reg.Blaylock@usm.edu
Kelly Lucas, PhD
Thad Cochran Marine Aquaculture Center, School of Ocean Science
and Engineering
University of Southern Mississippi
Ocean Springs, MS, USA
Kelly.Lucas@usm.edu
Michael D. Chambers
School of Marine Science and Ocean Engineering
University of New Hampshire
Durham, NH, USA
Michael.Chambers@unh.edu
Jim R. Stewart, PhD
OceanForesters
Ventura, CA, USA
JimStewart@oceanforesters.org
Steven F. DiMarco, PhD
Department of Oceanography
Texas A&M University
College Station, TX, USA
SDimarco@email.tamu.edu
Kerri Whilden, PhD
Department of Oceanography
Texas A&M University
College Station, TX, USA
KWhilden@tamu.edu
Binbin Wang, PhD
Department of Oceanography
Texas A&M University
College Station, TX, USA
BWang314@tamu.edu
MH Kim, PhD
Texas A&M University
College Station, TX, USA
M-Kim3@tamu.edu
Zach Moscicki
School of Marine Science and Ocean Engineering
University of New Hampshire
Durham, NH, USA
MoscickiZ@gmail.com
Corey Sullivan
School of Marine Science and Ocean Engineering
University of New Hampshire
Durham, NH, USA
Corey.Sullivan@unh.edu
Igor Tsukrov
School of Marine Science and Ocean Engineering
University of New Hampshire
Durham, NH, USA
Igor.Tsukrov@unh.edu
M. Robinson Swift
School of Marine Science and Ocean Engineering
University of New Hampshire
Durham, NH, USA
MRSwift@unh.edu
Scott C. James, PhD, PE
Departments of Geosciences and
Mechanical Engineering
Baylor University, Waco, TX, USA
SC_James@baylor.edu
Maureen Brooks
Horn Point Laboratory
University of Maryland Center for Environmental Science
Cambridge, MD, USA
MBrooks@umces.edu
Stephan Howden, PhD
School of Ocean Science and Engineering
University of Southern Mississippi
Ocean Springs, MS, USA
Stephan.Howden@usm.edu
Suzanne Fredericq
Department of Biology
University of Louisiana at Lafayette
Lafayette, LA, USA
slf9209@louisiana.edu
Stacy A. Krueger-Hadfield
Department of Biology
Univ. of Alabama Birmingham
Birmingham, AL, USA
sakh@uab.edu
978-1-5386-4814-8/18/$31.00 ©2018 IEEE
2
Antoine De Ramon N’Yeurt
Pacific Centre for Environment and Sustainable Development
The University of the South Pacific
Suva, Fiji
nyeurt_a@usp.ac.fj
Chris Webb
AI Control Technologies
Boca Raton, FL, USA
chris.webb@ai-ctec.com
Don Piper
OceanForesters
Ventura, CA, USA
dpiper1111@gmail.com
Abstract: The US Department of Energy Advanced Research
Projects Agency - Energy (ARPA-E) MacroAlgae Research
Inspiring Novel Energy Research (MARINER) program is
encouraging technologies for the sustainable harvest of large
funding research of macroalgae for biofuels at less than $80 per
dry metric ton (DMT). The Ocean Forests team, led by the
University of Southern Mississippi, is developing a complete
managed ecosystem where nutrients are transformed and
recycled. The team’s designs address major bottlenecks in
profitability of offshore aquaculture systems including economical
moored structures that can withstand storms, efficient planting,
managing and harvesting systems, and sustainable nutrient
supply. The work is inspired by Lapointe [1] who reported yields
of Gracilaria tikvahiae equivalent to 127 DMT per hectare per year
(compared with standard aquaculture systems in the range of 20
to 40 DMT/ha/yr). This approach offers the potential for
breakthrough yields for many macroalgae species. Moreover,
mini-ecosystems in offshore waters create communities of
macroalgae, shellfish, and penned finfish, supplemented by
visiting free-range fish that can increase productivity, produce
quality products, and create jobs and income for aquafarmers.
Additional benefits include reduced disease in fish pens, cleaning
contaminated coastal waters, and maximizing nutrient recycling.
Cost projections for a successful, intensive, scaled system are
competitive with current prices for fossil fuels.
Keywords: Gracilaria; Gracilaria tikvahiae; biofuels;
macroalgae; seaweed; aquaculture; breakthrough yields; algae;
ocean afforestation; seafood
I. I
NTRODUCTION
Ocean Forestry is an extension of natural processes in marine
ecosystems where macroalgae, bacteria, and animals transform
and recycle nutrients. Ocean Forestry supplements natural
processes by incorporating finfish/shellfish (both farmed and
free-range) and multiple species of macroalgae to increase
biomass production while providing a path to market.
A simplified nutrient transformation cycle (excluding
microscopic species such as plankton and bacteria) is shown in
Fig. 1.
The task outlined by the US Department of Energy
Advanced Research Projects Agency – Energy (ARPA-E) is [2]:
Funded by ARPA-E Funding Opportunity No. DE-FOA- 0001726
MARINER contract DE-AR0000916-1, University of Southern Mississippi,
prime contractor.
Fig. 1. Simplified ocean forest nutrient recycling
[T]o significantly broaden the opportunities for macroalgae
to be a significant energy contributor to a future low-carbon
world, especially for the production of biofuels…. [Through]
the development of transformational technologies to enable
a U.S. based macroalgae industry capable of producing up to
2 Quads of bioenergy by 2050, while also supplying the
world’s ever-expanding need for animal feed. The ARPA-E
MARINER Program will meet these goals by developing
innovative cultivation & harvest systems able to produce
macroalgae biomass that is cost competitive with terrestrial
biomass at energy-relevant scale. The primary technical
target is to demonstrate [at scale] Biomass Production Cost
$80/dry metric ton, without direct application of synthetic
fertilizer.
Our analysis shows that higher productivity (thus lower cost
per ton) results from natural nutrient recycling in a complete
ecosystem, which also provides both ecological and economic
benefits. For example, Buck et al. [3] found that about four wet
3
tons of shellfish
1
and/or seaweed will remove the organic
nitrogen emitted by 1 ton of finfish. More shellfish or seaweed
(quantities adjusted to the level of excess nutrients) could revive
dead zones. In addition, macroalgae could expand local fish
populations through the food and habitat it provides. Economic
benefits include the removal of both sea lice [4] and fish feces
by shellfish growing around fish pens, which potentially reduces
the cost of finfish aquaculture and decreases coastal
contamination from fish farms.
Results of this one-year project include a technoeconomic
analysis (TEA) of how an ocean forest ecosystem could
eventually achieve the ARPA-E goal of production costs
<$80/dry metric ton (DMT) of biomass plus a proposal for a
Phase 2 small demonstration to de-risk key elements.
II. O
VERVIEW OF THE
A
PPROACH
Our team will design and demonstrate complete systems for
use with any type of macroalgae so that anyone could adapt the
technology for their species and local conditions. Several team
members have worked with the University of New Hampshire
Open Ocean Aquaculture research farm, which tested
technologies for the culture of native, cold-water finfish and
shellfish species in exposed oceanic environments. The study
site was located 12 km off the New Hampshire coast in 52-m
deep water [6]. The system demonstrated the nutrient-
conversion cycle in Fig. 1. A similar UNH site close to shore
now raises fish, shellfish, and macroalgae biomass, all of which
are harvested and sold to local markets.
This Ocean Forest project plans to grow native macroalgae
in the Gulf of Mexico (GoM). Biologists recommended the red
seaweed Gracilaria tikvahiae [7], which grows to a length of
about 30 cm and yields about 12 DMT/ha/yr of biomass when
cultivated in ponds [8]. However, ARPA-E assumes that a
minimum of 25 DMT/ha/yr is needed to meet the $80/DMT
target [2].
III. D
ESIGN
C
OMPONENTS
A. Spiderweb Structure
The major issue in the GoM is damage from hurricanes and
storms. All structures permitted in U.S. waters of the GoM must
have a hurricane-contingency plan. We plan to submerge the
farm at a protective depth of at least 40 m, but at least 10 m
above the seafloor to avoid dragging the macroalgae and
shellfish in the mud. In minor storms, the system sinks a few
meters to lessen the effects of large waves on the macroalgae and
structure to reduce loss of crop and structural damage.
1
Recent unpublished work by M.D. Chambers, et al. has reduced this
to 3:1 per ton of finfish.
Fig. 2. Spiderweb structure overview.
Fig. 2 shows a macroscale view of a single unit, which at full
scale has a 0.5-km diameter. Netting or rope substrate for algae
growth is tensioned between structural radial spokelines.
Remote-controlled, adjustable-buoyancy float-ballast systems
are located at the connections of the spokelines and anchorlines.
Shellfish baskets are suspended from the lines between floats.
Openings in the growing area could allow marine mammals to
surface when passing under the structure. We are collaborating
with NOAA and other specialists to ensure that the final design
minimizes negative interactions with marine animals.
The structure was inspired by the structural resilience of a
spider web. Relying only on compliant rope structures,
distributed buoyancy, and changeable position in the water
column, the system can survive the extreme conditions in the
GoM. The spoked circular design distributes resistance to
hydrodynamic loads regardless of current direction. The spoked
structural foundation also allows for deployed geometries that
can easily handle the inaccuracies of marine anchor
deployments.
The structure also could be used for sugar kelp and other
species using longlines instead of the netting substrate shown.
The spider-web design
2
shown in Fig. 2 has no surface floats
over the main seaweed grow-ropes (only around the periphery)
allowing the Mow-Harvest-Bag System to move unimpeded in
a continuous spiral over the seaweed.
Together with the fish species attracted by the structure, the
shellfish metabolize nutrients in planktonic microorganisms into
forms more readily available to macroalgae. Increased nutrient
levels in the macroalgae “forest” increase biomass yields. This
ecosystems approach to nutrient supply means species valuable
to the seafood market can be co-produced to help offset the cost
of the structure.
As macroalgae age, they release carbon and nutrients they
have absorbed. The larger their size the more leaf tip break-off
and mucilage emissions. Therefore, frequent mowing to
maintain macroalgae biomass density between 1 and
10 DMT/ha could assist breakthrough yields of any macroalgae.
2
Developed by OceanForesters and University of New Hampshire
structural engineers.
4
B. Depth Control System
The depth-control system
3
is designed for unsheltered water
subject to storms. Fig. 3 illustrates two depth positions; the top
one shows macroalgae at their optimum growing depth and the
lower one depicts the suspended ballasts resting on the seafloor
when the structure is submerged, but the macroalgae and
shellfish and penned fish are several meters above the seafloor.
Fig. 3. System schematics showing surface and submerged positions
These float-ballast systems at the end of each spokeline
change the operating depth using minimal energy. The operating
depth in the surfaced position is passively controlled by surface
floats while the depth in the submerged position is passively
controlled by ballast weights hanging about 15 m below the
surface floats. When activated, valves on the ballast flood the
interior tank, which sinks the system. When surface conditions
improve, compressed air from the float forces water out of the
ballast chamber and the system rises. Intermediate mooring-line
floats maintain tension in the mooring legs regardless of position
in the water column.
When conditions are relatively calm, the system operates at
a growing depth of about 2 m, sufficiently deep to avoid surface
chop, but allowing for optimal light absorption for the species
involved. When storm conditions are rough, the system is
submerged below the highest energy wave environment
allowing the system to minimize exposure to extreme events.
Data from Hurricane Andrew [9] indicated that submerging the
system to 50 m cut the hydrodynamic loads on the system by
more than 50%. This means that a cost-effective system need
only be sized for the moderate conditions at depth.
C. Perennial Macroalgae Growth – Breakthrough Yields
“Typical” macroalgae yields are ~30 DMT/ha/yr, but
Lapointe in a year-long experiment showed that Gracilaria
tikvahiae could produce 127 DMT/ha/year [1], provided the
macroalgae is maintained at a low density by frequent harvests.
Lapointe harvested Gracilaria weekly and maintained a density
of 2 to 8 DMT/ha while providing optimal nitrate and phosphate,
which we can supply using nutrients from waste products
recovered from the energy-conversion process.
Increased conversion of organic to inorganic nutrients
increases macroalgae yields and reduces nutrient shadows. As
3
Developed by AI Control Technologies, Texas A&M University,
and OceanForesters.
they approach maximum size/density, macroalgae (more so kelp
than Gracilaria) lose mass due to tip breakoff and mucilage
emissions [10]. Animal biomass facilitates conversion of
organic nutrients to inorganic nutrients. These “losses” of in-
farm organic nutrients are recovered by shellfish and finfish,
whose excretions nourish the macroalgae.
Recent information [11] demonstrates that some plant and
animal ecosystems are shrinking in response to global warming.
High seawater temperatures also could reduce growth of other
organisms. Our systems could counteract this by submerging the
seaweed to cool the plants in deeper waters.
D. Plant-Mow-Harvest-Bag System
Gracilaria tikvahiae, which grows to 30 cm, will be
cultivated at an optimum depth of about 2 m. The seeding
process features a double-layered net system as shown in Fig. 4.
Automated equipment contains a supply of macroalgae cuttings
that are distributed over the bottom substrate net. Then a top net
is rolled over the cuttings and sealed to the bottom net with
staples. The mesh openings of the top netting allow the
Gracilaria to grow freely and expand between and through the
netting layers. The top netting ensures that macroalgae will
remain in place when submerging the growth system.
Fig. 4. Automated seeding of Gracilaria tikvahiae between two nets.
When it reaches about 10 cm high, the Gracilaria is mowed
by a special cutter pushed by a wheeled autonomous vehicle and
pumped through a hose for bagging as shown in Fig. 5.
Fig. 5. Harvesting Gracilaria tikvahiae using an automated cutter and bagging
system.
snowblower-action
hedge trimmer-action
AUV “tractor”
w
ith spacer
w
heels o
v
er substrate
Harvest into bags using hydraulic conveyor hose
5
Relatively small (20- to 40-cm diameter) wheels on the
slightly negatively-buoyant automated underwater vehicle
(AUV) maintain a specified distance above the net. A hose
connected to a pump conveys cut macroalgae to the bagging
system. A similar system could be used for kelp, except that the
AUV would be free floating (without wheels) to cut at the
optimal height to facilitate rapid regrowth, and the kelp would
rise to the surface to be collected by a treadmill as shown in Fig.
6.
Fig. 6. Collecting treadmill and hydraulic bagging system
Algae will be compressed using a hydraulic ram into either a
porous or impermeable bag with a porous end to allow water to
escape (Fig. 6). Once full, both ends will be sealed and the bag
will be picked up by a remotely piloted tug for energy
processing. Fig. 7 shows the towing system conceived by C.A.
Goudey and Associates.
4
Fig. 7. Side view of a towing system for transporting seaweed.
Concept papers submitted to ARPA-E OPEN 2018 explain
the benefits of harvesting macroalgae into impermeable
geosynthetic membrane containers for either direct energy
processing [12] or storage to even out the flow of product to the
energy processor [13].
E. Wave Energy Power System
Texas A&M is developing a wave-energy device described
in their ARPA-E OPEN 2018 concept paper [14], which is
competitive with solar PV for powering offshore aquafarms.
Wave-tank tests suggest that the Surface Riding Wave Energy
Converter could eventually have a levelized cost of electricity
below $0.35/kWh.
F. Wide Applicability
Fig. 8 shows over 5 million available hectares (in green)
between 50- and 100-m depths in the GoM. The unshaded areas
have other uses including military, shipping, oil and gas, etc.
4
Image downloaded from http://cagoudey.com/
Fig. 8. GoM area between 50 and 100 m deep available for Ocean Forests
(prepared by NOAA).
G. Technoeconomic Analysis
Current projections show high variability in $/DMT with
significant uncertainties due to:
• Yield in DMT/ha/yr ranging from 30 (normal) to 120 (if
Lapointe’s 1978 results are achieved),
• Density at time of mowing ranging from 1 to 10 DMT/ha,
• Sufficient growth rate, which is dependent on nutrient
availability, which is, in turn, affected by the percentage of
incoming organic nutrients that are transformed by the
shellfish and other animals into inorganics that stay in the
ocean forest long enough to be absorbed by the macroalgae,
and
• Rising ocean temperatures, which could decrease yields.
If these uncertainties can be resolved favorably, it is possible
that Ocean Forests could grow and harvest even a small
macroalgae, such as Gracilaria tikvahiae, for <$80/DMT, while
simultaneously producing large quantities of food for humans
and animals.
H. Future Research
MARINER has nine teams competing for three at-sea
demonstrations. Fig. 9 shows a possible location for a one-
hectare Phase 2 demonstration to prove the concepts required for
breakthrough yields. A menu for Phase2 projects includes:
A four-sided structure with substrate appropriate for:
• Automated planting of any tropical macroalgae,
• Testing other seeding and harvesting arrangements,
• Frequent mowing to measure growth rates and
potential yields,
• Adding depth control to prove this component,
• Shellfish to quantify nutrient conversions,
• Demonstration of the mow-harvest into bags, perhaps
with a modified AlgeaNova system
5
.
5
See AlgeaNova at http://www.algeanova.com/en and minutes 20ƺ22
of video at https://www.youtube.com/watch?v=gE3EXxC4Mf8&feature=youtu.be
Mow-harvest catamaran
Cinch strap to seal back end
Conveyor
(treadmill or hose)
Hydraulic ram
position a
HarvestBag
position b
HarvestBag System
6
Fig. 9. Fig. 9. Potential location for a Phase 2 demonstration at 75 m depth
IV. D
ISCUSSIO N
The team has a one-year contract with ARPA-E and will
present its final report in April 2019. This paper presents a
glimpse of the work in progress to be presented at the Oceans18
Conference. Subsequent published papers will elaborate on the
solutions outlined above.
V. C
ONCLUSIONS
Preliminary results show the possibility of significantly
higher yields/area for any macroalgae and imply potentially
profitable steps to meeting U.S. energy demand as follows:
(1) Make a small impact on global food security with
products from permanent Ocean Forests, including shellfish and
finfish or human food and macroalgae converted to livestock and
fish feed. This can happen without nutrient recycling.
(2) Make a significant impact in global food security and
human health by teaming with coastal water resource-recovery
facilities to use treated wastewater to grow food. This closes the
nutrient cycle of human food to plant food to human food.
(3) After many forests are operating successfully, energy
companies recognize robust macroalgae feedstock supply. This
starts a virtuous spiral expanding macroalgae-to-energy
infrastructure, which extends the recycled nutrient supply to
grow more macroalgae. The expanding spiral leads toward
macroalgae biofuels meeting much of the global energy demand.
This system could eventually produce billions of gallons of
biofuels without the use of any land, fresh water or added
fertilizers (only the recycled nutrients from energy conversion).
R
EFERENCES
[1] B. E. Lapointe, Some aspects of the growth and yield of Gracilaria
tikvahiae in culture, Aquaculture, 15, 185ƺ193, 1978.
[2] ARPA-E Funding Opportunity No. DE-FOA-0001726, pp. 4–5 and 20,
2017. (Downloaded from https://arpa-e-foa.energy.gov)
[3] B. H. Buck, N. Nevejan, M. Wille, M. D. Chambers, and T. Chopin,
Chapter 2. Offshore and multi-use aquaculture with extractive species:
seaweeds and bivalves, 48ƺ51. In B.H. Buck and R. Langan (eds.),
Aquaculture Perspective of Multi-Use Sites in the Open Ocean,
DOI: 10.1007/978-3-319-51159-7_2, 2017.
[4] M.D. Chambers et al., unpublished.
[5] University of New Hampshire Open Ocean Aquaculture research farm:
http://ooa.unh.edu.
[6] N. Goseberg, M. D. Chambers, K. Heasman, D. Fredriksson, A. Fredheim,
and T. Schlurmann, Technological approaches to longline- and cage-
based aquaculture in open ocean environments, Chapter 3 in B. H. Buck
and R. Langan (eds.), Aquaculture Perspective of Multi-Use Sites in the
Open Ocean, DOI 10.1007/978-3-319-51159-7_3, 2017.
[7] C.F.D. Gurgel and S. Fredericq, Phylogeography of Gracilaria tikvahiae
(Gracilariaceae, Rhodophyta): A study of genetic discontinuity in a
continuously distributed series based on molecular evidence, Journal of
Phycology, 40, 748ƺ758, DOI: 10.1111/j.1529-8817.2004.03070.x, 2004.
[8] FAO Training Manual on Gracilaria Culture and Seaweed Processing in
China. Zhanjiang Fisheries College, People's Republic of China, 1990.
[9] T. R. Keen and S. M. Glenn, Shallow water currents during Hurricane
Andrew, Journal of Geophysical Research Atmospheres, 104, C10,
23,443ƺ23,458, 1999.
[10] M. I. Lucas, R. C., Newell, and B. Velimirov, Heterotrophic utilisation of
mucilage released during fragmentation of kelp (Ecklonia maxima and
Laminana pallida) II. Differential utilisation of dissolved organic
components from kelp mucilage. Marine Ecology Progress Series
4(1):43-55, 1981. DOI: 10.3354/meps004043
[11] M. Zaraska, Shrinking animals. Scientific American, 49, 2018.
[12] K. Hopkins, In-Ocean Submersible Bag Biomass Biorefinery, 2018.
Unpublished but posted at
https://drive.google.com/open?id=1Fus7icjapwqu_3yeY31JB4Sig7ehgQnQ.
[13] S. F. DiMarco, Sub mersible Bag Biomass Storage with Dewaterin g, 2018.
Unpublished but posted at https://drive.google.com/file/d/1En2p3-
5Th6dsC-6yx-oJ34ccn9kMoPAO/view.
[14] H. Y. Kang, M. H. Kim, K. A. Chang, and H. A. Toliyat, Surface riding
wave energy converter, 2018. Unpublished but posted at:
https://drive.google.com/open?id=1f1_SfQc_6SCkuuoqwKat98rfRzGU
PUjN.