Seaweed - Biofuels
BLUE BIOECONOMY
Writer: John Cunningham
Photographs: John Cunningham, Green Wave
November 2017
Updated July 2020
Biofuels have become synonymous with ecosystem degradation and displacement of essential local agriculture and from a promising start have become almost universally discredited. Is there a viable and realistic alternative?
Held responsible for displacing local populations from agricultural land and for clearing native forest cover and in some instances, pushing up global food prices by 75%, some scientists have observed that production of biodiesel from soya results in carbon equivalent pollution four times greater than that of fossil diesel.
We need a reverse gear
A recent report for the UN calculated that one third of the world’s soils had been highly degraded through intensive agriculture that they were no longer fit for purpose, creating greater pressure on undamaged soils to feed rapidly expanding populations, leading to increasing competition, famine and conflict. Further soil loss through erosion by flood and drought and wind is accelerating as a result of Climate Change can only compound an already intractable problem. The remaining soil of the world are clearly to valuable to be given over to biofuel crops.
Few in the Real World can be unaware of our desperate need to transition from Fossil Fuels to clean energy but our options are limited, time is short and current proposals at best merely serve to reduce emissions and will have little impact on the threshold 400+ppm CO2 currently in our atmosphere. This level of CO2, amongst many greenhouse gases, threatens to push global temperatures beyond the +2ºC (the three warmest years on record being 2014, 2015 & 2016), a catastrophe for a dangerously destabilising Arctic and the rapid deterioration of it’s biogeographic components. We need a reverse gear.
A positive ecological footprint in almost all respects
In our hour of need, a miraculous solution is emerging offering an alternative which, according to the World Bank, has the capacity to reduce the ecological footprint of humanity.
Large scale, open ocean macro algae aquaculture has the potential to offer the feedstock for the forthcoming Algal Biofuel Revolution. Enormous Solar Batteries of seaweed are quietly charging, with the potential to offer a paradigm shift towards climate positive fuels, which reduce overall CO2 levels in their lifecycle.
Algal biofuels are not only free of the baggage land based sources, at up to ten times more bioproductive than the most efficient terrestrial agricultural system, they require no valuable land or deforestation, no fresh water, no fertiliser, no pesticides and virtually no labour. Whilst many habitats are suitable for seaweed aquculture, the future of high volume, low value biomass may be best met in the open ocean, where conflict of interests are fewer.
Not only do seaweeds, particularly brown seaweeds offer the potential of climate neutral energy, the ecological footprint of seaweed is positive in almost all respects, providing nutritious food for an ever expanding global population without recourse to nitrate fertilisers or further land degradation and their contributes to environmental wellbeing and climate change mitigation well in excess of the biological and economic costs of production.
The emerging algal biofuel industry will require significantly more seaweed as a feedstock thancould safely be harvested from coastal areas, however developments in seaweed farming techniques, such as advanced textile substrates and mechanical harvesting technology are reducing the price point at which this valuable biomass can be produced and scientists are working to develop industrialised scales of production.
JONAA © GreenWave
The most accessible form of algal biofuel is methane
A key component of making macro algae biofuels economically viable has been the efficiency with which the energy locked in the polysaccharide sugars of algae can be liberated and optimised. Industrially available microbes are incapable of metabolising alginates, which constitute half the content of seaweed and the search for the key enzyme which would liberate these sugars ended in the digestive tract of the exclusively seaweed fed adult male North Ronaldsay sheep. Walled off from the islands pastures, countless generations of enzymes in hundreds of generations of sheep, produced highly specialist bacteria capable of the most efficient breakdown of these sugars and the most efficient recovery of their energy. Once identified, it was discovered that these microbes are easily engineered and can be tweaked to produce butanol or jet fuel.
The most accessible form of algal biofuel is methane and it’s production in theory, the simplest. The complex sugars, polysaccharides, contained in seaweeds, with the assistance of the above enzymes and in the absence of oxygen are easily broken down into methane and other products in the process of Anaerobic Digestion (A.D.).
The scale of A.D. production may be small, serving individual farms and communities with gas to fuel a generator cleanly and cheaply or on a municipal scale serving towns or industrial plants, where the methane can be pumped directly into fuel cells to produce electricity, piped into mains gas or burned a heat source. Containing no fibrous lignin, the leftovers reduce when decomposed to a mineral enriched slurry which can be applied as a super fertiliser without further processing.
The main drawback of A.D. is the byproduct, hydrogen sulphide (H2S) produced by Sulpher Reducing Bacteria. Although highly toxic and corrosive, H2S can be scrubbed from the gas mix rendering the remaining methane safe to use.
Bioethanol is second easiest means of recovering the solar energy fixed in seaweed and is produced by the familiar two stage process of fermentation and distillation. The exceptional biomass productivity of brown seaweeds fixes five times more carbon per ton than their closest competitorsyielding 1500 US gallons of ethanol/acre.
Algal bioethanol is a highly versatile source of ecologically “Free” energy and is currently a compulsory additive to petroleum based fuels in many countries in an effort to reduce fossil CO2 emissions, however current supplies are mainly derived from contentious sources and often merely stretch the efficiency of the consumption chain, using the waste products of other industries rather than closing the loop.
JONAA © GreenWave
The third and possibly most interesting potential of algae is in the production of Biocrude. Mimicing millions of years of geological pressure and temperature in a matter of minutes, the long chainpolysaccharides, are cracked and refined into fractions of biocrude by the process of Pyrolysis. These energy dense liquid fuels could become a viable replacement for the fossil fuels currently propelling most of the worlds ships or generating electricity in power stations at huge ecological expense.
Pyrolysis involves the rapid heating of brown macro algae to in excess of 450ºC in the absence of oxygen. Economically significant quantities of both both biodiesel and glycerine have been fractionated from this biocrude which will eventually produce a cost effective alternative fuel source once the technical challenges of large scale production have been overcome. As pyrolysis is very energy intensive, the obvious source of this power would be from parallel processing of algae methane or ethanol.
In October 2016, project “Macro Cascade” was launched to run for 20 months. It is a consortium of European companies and research institutes exploring all elements of the macro-algae value chain with Matis in Iceland engaged in similar work. Seagas in the UK is a consortium set up to explore the potential of seaweed derived methane. DuPont, currently the leader in the seaweed biofuel business estimate that if 2.5% of the North American coast was used for the cultivation of seaweed, 6.8 billion gallons of fuel could be produced annually.
US Navy have conducted extensive trials of algal biofuels in a variety of their vessels with the promise of energy circularity as ships are fuelled with organic algal biodiesel, proving their viability and in combination with other non fossil fuels may yet replace the use of highly toxic Heavy Fuel Oils (H.F.O’s) in ships.
A wave of Heavy Fuel Oil. JONAA © John Cunningham
Researchers at the University of Aberdeen recently revealed that the sub zero temperatures of the waters of the North Atlantic would significantly inhibit the ability of oil eating bacteria to clean the oceans after a spill. The dramatic increase in maritime traffic in the region clearly elevates the risk throughout the area. It appears increasingly likely that HFO’s will eventually be banned in The Arctic, however fossil fuel alternatives only partially resolve the problem and an organic carbon neutral alternative would be the obvious choice.
The development of algal biofuel has the potential to revolutionise energy supplies and the economies of remote and marginalised communities, providing locally grown fuel for generators and a cash crop, income and jobs. The unique capacity of seaweed to sequestrate atmospheric carbon in combination with ingenious developments in energy efficiency and storage offer the limited window of opportunity to realistically address and ameliorate the worst effects of Climate Change, bypassing government inaction, grow our own energy and actively remove Greenhouse Gases from the air and seas. ▢
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