Producing energy crops for biogas is not new in Europe. However, highest yielding energy crops in a tropical environment and combined use of wastes and high technology in a very sustainable approach to produce power is something never happened before. 

Tibbar Energy, is going to produce 7MW of power through anaerobic digestion (AD) of biomass in a unique new project involving most advanced technologies from Europe and highly yielding energy crops. An amazing group of companies and experts including our firm, have been providing best sustainable solutions.

An important concern from the beggining of this project was to honestly and seriously care about environmental aspects. This included water and nutrient cycling as well as impacts on coral reef, odors and many other issues that are extremely important in a small beautiful island like St.CroixA long agricultural report full of information and data analysis on best practices to consider in local farmlands has been released in December 2013. In order to help Tibbar Energy producing and improving management of energy crops in the US Virgin Islands, we wanted to bring all “best practices”, technical support and strict sustainability criteria from all EU experiences considering perennial bioenergy crops and biogas.

Tibbar Energy project has been facing several issues to reach maximum sustainability from farming operations and industrial anaerobic digestion of feedstocks and waste management. This was explained recently in an article issued b y Anna Simet from BIOMASS MAGAZINE:

Besides 1,500 acres of Giant King Grass, other digester substrates include fats, oils, greases and food waste, via a partnership with the Virgin Islands Waste Management Authority, which has also signed an agreement with Tibbar to sell its treated wastewater for irrigation. The wastewater is currently discharged into the ocean. Engineering and design are also on schedule, Tomyn said. Tibbar is working with Layne Heavy Civil Inc. based in Mission Woods, Kan., one of North America’s largest waste water treatment engineering, construction and procurement contractors. Layne has a strategic partnership with entec biogas gmbh of Austria, which has built over 100 biogas plants worldwide. The full electrical output of the facility is under contract to the Virgin Islands Water and Power Authority through a 25-year power purchase agreement. Tibbar expects to be producing power by June 2015.

Learn more details on Tibbar Energy here.

Tropical Energy Crops and biogas

Highest potential productivity from energy crops can basically be achieved from cultivation of so called “warm” grasses. These species have four carbons photosynthesis methabolic pathway, with outstanding water, nitrogen and radiation use efficiency. Most of these species (including Miscanthus) have best performance in warm climates. Different from all projects in Germany, Denmark, Austria and other European countries with a long record of biogas projects based on forage maize and manure, the sugarcane sector and warm cliamte of tropical countries offer a significant opportunity  for lignocellulosic energy crops as Napier grass, Guinea grass and many other species with extremely high yield. A biogas digester requires highly digestible organic matter to produce best biogas yields in terms of methane per acre and reduced economic costs of the methane at the gate of the digester.

Additionally, nutrient and water cyclings need to be addressed to obtain highest sustainability and return organic matter and nutrients from collected as “digestate” after anaerobic digestion occurs. The final product is methane production and a highly valued digestate with enormous potential for farming and gardening.

 Sustainability of energy crops for biogas in the Caribbean

Discussing sustainability of these alternatives might require a complete new post about it. However, some key issues need to be considered and mentioned if one needs to discuss on environmental benefits and impacts:

  • Currently, small tropical islands face several risks because of energy demand and a fossil carbonized economy. Renewable energies and perennial species could be a greener and more reasonable approach to have

    Current situation is not ideal. Currently, small islands and several tropical countries use imported fossil energy resources with extremely high risks and impacts on the environment. Those resources are also economically expensive and do not allow companies to build new long term business because of cost uncertanties and oil, gas and coal prices rising scenarios. Additionally, monocultures, land abandonment and a need for new farming alternatives is a key issue in most tropical sites where food production is not always highly competitive. Sinergies and a new approach around energy and food sectors is required.

  • Lignocellulosic energy crops for biogas are not corn biofuel. Several countries worldiwde have tried biogas power facilities with great advatantages for the environment. Producing perennial grasses with very low inputs combined with other feedstock as manure, sugarcane vinasses or food wastes, can be very sustainable alternative from the point of view of life cycle and carbon footprint. Not only fossil energy can be replaced. Also fossil energy currently consumed from fertilizers might be replaced when solid and liquid digestate coming out from the digester can offer a great alternative for local farming activities. The emission saving potential in a case like this are much more efficient than producing corn ethanol..
  • Existing tropical grasses in the Caribbean can be efficiently managed to produce highly digestible feedstock with extremely low inputs and several social and environmental benefits on soil, water, nutrients and carbon cycles. Photo: US Virgin Islands. Source: Bioenergy Crops Ltd (August 2013)

    Existing tropical grasses in the Caribbean can be efficiently managed to produce highly digestible feedstock with extremely low inputs and several social and environmental benefits on soil, water, nutrients and carbon cycles. Photo: US Virgin Islands. Source: Bioenergy Crops Ltd (August 2013)

    Soil erosion control and best water management. Energy crops in marginal lands require best approach in terms of sustainability. When producing energy crops in tropical environments, unused lands or low competitive farmlands need to be firstly addressed. When companies consider energy grasses, they often start thinking on highly productive species and crops height over 11 feet . However,  many cuttings and plant recovery can be a greater issue to control. Additinally, there are dozens of alternative species to consider when soil, climate and farming operations may determine high variability of conditions in large scale projects . Some low cost grasses, intercropped annual and perennial legumes with low water requirements, organic fertilized perennial and annual crops and a great biodiversity might all be feasible alternatives to consider while producing low cost feedstock with great digestibility in terms of methane productivity. Drought tolerant species consuming less water or crops with longer roots determining best erosion control measures are all possible benefits in this kind of projects.

Learn more on bioenergy crops for biogas here.

Learn more on our independent group vissions for a biobased economy.