Three years after awarding the project to deal with Cayman’s landfill problems to a consortium led by Dart, now known as ReGen, plans for a waste-to-energy facility are finally taking shape.
The current timeline projects that the landfill remediation of the north mound of the George Town landfill will be completed next year.
The waste-to-energy and recycling facilities, as well as a lined landfill for any residual waste that remains after burning most of the trash, should be commissioned and operational by 2024.
The project stems from a public private partnership deal between government and the consortium that was finally signed in March of this year.
At the 5th Caribbean Infrastructure Forum, which took place virtually in March, a discussion by waste-management experts highlighted the many challenges faced by countries in the region to deal with the waste they produce. It also showed why waste-to-energy may not be an option available to all.
Wealth and size matters
Vincent Sweeney, the head of the Caribbean Sub-Regional Office of the United Nations Environment Programme, noted that, despite having similar issues, there were vast differences between regional neighbours.
Cayman and Bermuda, for instance, could not be compared to Eastern Caribbean islands, because they are able to implement waste-management measures that are completely unaffordable in other places.
For other solutions, size matters and what may feasible in Haiti or Cuba may not apply to a small cay in the Bahamas.
Small size can also be a limiting factor for recycling due to the remoteness of many islands and their lower economies of scale, Sweeney said.
Most island nations do not have manufacturing plants to process and recycle plastics, metals and glass and turn them into new products or packaging.
When the recycled materials must be shipped off island that adds collection, packaging, shipping and handling costs. Quite often small island nations will have little sway in the markets for recycled goods and the return on investment of recycling programmes will be negative, said Kirk Outerbridge, chief engineer in the Ministry of Public Works in Bermuda.
“Globally recycling makes [economic] sense but at the local level recycling can be a pure expenditure,” he said.
Because recycling is so difficult in an island context, Martin Edelenbos, the waste-management specialist for Dart in Cayman, said it would be beneficial to use the progress that has been made by the recycling movement in terms of consumer education and focus more on the reduce and reuse aspects of the three Rs often mentioned in connection with trash.
“That’s something where we can make a lot of headway,” he said.
Edelenbos agreed that Cayman is wealthier than most other Caribbean islands but nevertheless similar issues affect the Sister Islands.
The size and remoteness of Cayman Brac and Little Cayman raise the question of whether to treat the waste they produce on island or transport it to Grand Cayman to be treated there.
“For the moment it looks like we’ll be transporting it but once the system starts up and running, we’ll have to see,” he said.
Likewise, Edelenbos said waste-to-energy technology is not only expensive in general but even more so on a small scale in an island setting such as Cayman.
While Dart is proposing a technology that is reliable, robust and well understood, he said, the cost per ton of waste is going to be very expensive, as the proposed facility will process only 110,000-120,000 tons a year – significantly less than the average thermal treatment plant.
Lower greenhouse gas emissions
One of the advantages touted in connection with burning waste to generate energy is that even though it releases CO2 into the atmosphere, the CO2 emissions are lower than if the waste is stored in a landfill.
For instance, methane, which has roughly 25 times the greenhouse gas effect of CO2, will be released from decomposing waste in a landfill into the atmosphere, if it is not captured. Burning the waste instead will prevent this type of greenhouse gas production.
How much CO2 is emitted per tonne of waste incinerated depends on the composition of the waste. A large percentage of waste, such as paper and wood, is considered CO2 neutral, because the same amount of CO2 captured during its lifetime is released during burning.
Edelenbos noted that the ratio of fossil fuels compared to carbon-neutral materials that are running through a waste-to-energy facility is important. “I think it’s generally accepted that it’s about 50%. So, waste-to-energy is about 50% renewable energy,” he claimed.
However, by far the largest greenhouse gas impact comes from the amount of diesel fuel that no longer has to be burnt to generate electricity.
The more fossil fuels that can be substituted in electricity production with waste-to-energy, the larger the CO2 savings.
In Cayman, currently 97% of electricity comes from diesel fuel.
Outerbridge concluded that “in essence, it’s a pretty substantial impact in terms of global pollutants”.
The long-term impact of waste-to-energy
The concern with thermal waste treatment plants is therefore not so much with global pollutants in the form of greenhouse gases but with local pollutants such as dioxins and heavy metals.
These persistent pollutants remain in the environment and can build up over time.
In Bermuda, the government decided in the mid-1980s to phase out landfilling its waste and build a waste-to-energy incinerator. The Tynes Bay facility was commissioned in 1987 but it took three years of environmental impact studies and design changes for it to come online.
Outerbridge explained that the plant’s design from the 1980s meant the facility did not have top-of-the-line technology that is available today.
As a result, the operators of the plant had to implement measures, like raising the stack height, to mitigate the effect of pollutants rather than capture them.
The small landmass of Bermuda and its remote location also helped minimise the environmental impact on land.
Since the facility was constructed, the government of Bermuda has done studies and monitored dioxin levels.
Outerbridge said that three decades later “we have not seen a lot of impact”.
Although the latest study did show a large concentration of dioxins at the plant site, the signature of the pollutants indicated that they were related to the internal combustion engines of the trucks coming to the facility and not the exhaust gases.
Typically, pollutants are scrubbed from the exhaust gases before they can enter the surrounding environment.
In most cases this involves a watery slurry of pulverised limestone, a naturally occurring calcium carbonate that can react with sulfur dioxide.
In Bermuda, however, the environmental impact of bringing in shiploads of lime and exporting the contaminated lime so that it can be disposed in a hazardous waste facility off island was considered greater than the impact of acid rain on surrounding seas.
Edelenbos explained that Cayman’s waste-to-energy facility, in contrast, will have “all the bells and whistles”.
This will include the importation of lime to manage acid gases, as well as the “best available technology” for emission controls.
This technology will concentrate the toxins that are coming up in the stack in fly ash. The process shifts the concern from any emissions from the stack to having to manage the fly ash properly, Edelenbos said.
ReGen is proposing to mix this material in cement and then disposing of that mixture into a lined landfill. This process will again involve importing materials.
“So it’s a more complicated system, but it’s very sound in terms of controlling emissions,” Edelenbos said.
“In this day and age”, he said, it was neither desirable nor possible to obtain approval for a waste-to-energy facility without implementing the best available technology.
Dealing with difficult waste
Because not everything can be burned in the thermal treatment plant and some waste is problematic when stockpiled, different strategies are needed to deal with scrap metal, end-of-life vehicles, tyres or waste oils.
Edelenbos said there will be different considerations in each jurisdiction. In Cayman, where discarded vehicles are “a real problem”, the vehicles will be baled and shipped abroad. The same applies to scrap metal and appliances after they are depolluted.
While they have some value, it is not sufficient to cover the cost of the recycling efforts, including processing and shipping to market. In order to deal with the cost, Edelenbos suggested having some form of additional import duty so that the disposal cost is paid upfront.
“When it comes to tyres, they’re obviously a real problem, because they are designed to be indestructible,” Edelenbos said. “I encourage anyone that is facing a problem to not stockpile the material. And I think that goes for end-of-life vehicles and appliances as well.”
If there is no active programme in place to manage these types of waste, they should be landfilled rather than stockpiled, or they will lead to greater problems in the long term, such as the recent landfill fires in Cayman, he said.
In Cayman, the aim was to sell shredded tyres to market, but this was largely unsuccessful and the current plan is to burn tyres in the waste-to-energy facility.
Waste oils, including anything from vegetable oils to engine oils, are difficult to deal with on an island, Edelenbos noted, but they have value and can be shipped overseas or they can be burned for energy locally.
For medical and pharmaceutical waste, there is already a furnace that burns infectious waste, but the plan is to create a new facility with a small air-starved furnace that will also scrub the emissions released in the burning process.