Energy recovery from waste: A ‘circular economy’ opportunity for the Caribbean

By: Roberto G. Aiello, Principal Energy Specialist at IDB; and Juan Ramon Morante, Director of IREC

Solid waste disposal is a sensitive issue for Caribbean countries given land constraints and the importance of natural ecosystems for their tourism-based economies. This is exacerbated by increasing volumes of waste and the lack of integrated solid waste management practices. Waste has multiple origins, including municipal, sewage, agriculture, bio medical, industrial, and poses environmental and sustainability challenges. Support for climate action is one of the pillars of the Inter-American Development Bank’s Vision 2025 strategy. Opportunities for waste-to-energy exploration in the Caribbean aligns with this objective in terms of promoting sustainability and generating new business.

As it relates to municipal solid waste, Latin America and The Caribbean is estimated to generate 1 kg per person per day on average, with some countries in the Caribbean well above that figure (e.g. The Bahamas 1.89; Barbados 1.73; Trinidad and Tobago 1.50)[1].  These figures do not include waste from cruise ships, which could significantly increase the average in some locations. When it comes to plastics, UNEP reports that approximately 76% of plastic produced worldwide from 1950-2017 became plastic waste, ending up in landfills or dumpsites. Every minute, the equivalent of one garbage truck of plastic is dumped into our oceans.

Globally, waste is slowly but increasingly turning from being a nuisance to an asset by means of recycling practices or energy recovery for non-recyclables through innovative technologies. Examples of environmentally sound energy recovery systems from waste include, (1) capturing the methane for power generation or other uses from anaerobic digestion (caused by a lack of oxygen) of organic waste, (e.g. fraction of municipal waste and from cruise ships, sludge from wastewater treatment plants, livestock manure, agricultural waste, forestry residues, and organic residues produced in many industries); (2) treating waste not apt for anaerobic digestion or composting with pyro-gasification technologies,  generating a mix of carbon monoxide and hydrogen known as syngas which can be used for power generation. The waste is previously sorted to be more homogenous and there is no incineration involved in the process; and (3) treating selective waste with new technologies to produce hydrogen. Residues from trimming trees in urban and rural settings can also be used for energy applications through efficient collection, and handling[2].

Commercial viability of each option depends on multiple factors, such as quantities of waste to be processed, waste composition, calorific value, waste management regulations and practices, energy market demand, and economic incentives. Based on the scale requirements, it appears that anaerobic digestion has in general broader applicability than the other treatments. In Denmark, for example, biomethane production is close to 40% of the total natural gas consumption, demonstrating the energy potential of farm/agricultural waste. It is important to note that selective collection of the organic portion of municipal waste, as well as waste from hotels, restaurants, food markets, cruise ships, among others, is more productive than residues from livestock, which are generally diluted with cleaning water, or from agricultural/forestry waste with higher levels of lignin. In addition to biogas, anaerobic digestion of different types of organic waste, properly combined and mixed, usually produces a residue (digestate) that can be used as fertilizer in agriculture. This provides a relevant economic value added to waste processing that goes beyond energy recovery.

Global demand for climate neutrality and sustainability is shaping new policy, legal and regulatory frameworks for managing waste with selective collection and/or waste separation. This includes new standards for solid waste management facilities, and disposal of agricultural waste and forests. Notably in March this year, Heads of State, Ministers of Environment and other representatives from 175 nations endorsed a resolution at the UN Environment Assembly in Nairobi to End Plastic Pollution and forge an international legally binding agreement by the end of 2024 that addresses the full lifecycle of plastics, including their production, design, and disposal[3]. Energy recovery is a route that would provide solutions in all these areas, avoiding opening dumpsites and landfills, and adding value through energy generation and co-products such as fertilizers, and contributing to the promotion of a circular economy.

Caribbean countries are highly dependent on fossil fuels, and they are working hard to increase the share of renewables. Waste-to-energy could play an important role where the cost of electricity is high, and at the same time contribute to an integrated and sustainable solid waste management system. The examples shown above underscore that energy potential from waste is not negligible and could be of strategic value to some countries of the Caribbean. This is especially true when considering waste from cruise ships that could contribute to the viability of investments should volumes be large enough. Without a doubt, it is something worthwhile analyzing.