(587l) Industrial Symbiosis at an Industrial Park in Trinidad and Tobago: A Focus on Carbon Dioxide

Trinidad and Tobago (T&T) is known for having high carbon
dioxide (CO₂) emissions per capita. This twin-island state, which is
rich in oil and gas, is renowned as being the largest emitter of CO₂
in the Caribbean. In 2016, T&T was ranked as the country with the second
highest CO₂ emissions per capita with a value of 25.72 metric tonnes¹.
A significant proportion of the emitted CO₂ originates from
industrial sources and in 2014, it was reported that 74% of T&T’s CO₂
emissions resulted from the industrial sector².

In Trinidad there is a large industrial park, the Point Lisas
Industrial Estate, which houses the majority of the petrochemical industry. This
industrial park contains several ammonia, methanol, urea, urea-ammonium
nitrate, melamine and cement plants. Therefore, in an aid to reduce the level
of emissions, ways in which the industrial park could be improved from an
ecological standpoint need investigation. Before any suggestions for
improvement can be made, the industrial park as it currently exists should be
evaluated. To this end, a linear input-output model was developed of a simplified
industrial park, which would exhibit the main characteristics of the large
industrial park. The purpose of the model was to assess the current level of
industrial symbiosis within the park, and highlight potential areas for
improving its level; that is, sharing and reuse of resources to create shared
value. MATLAB^® was employed as the modelling environment.

From the material flow network and input-output tables developed,
it was found that there exists an embryonic level of industrial symbiosis in
the industrial park, but there is substantial room for growth. The existing culture
of industrial symbiosis is based on the commercial interests of the local
industrial community, rather than being fuelled by government subvention. CO₂
is one of the by-product streams being exchanged between companies. The ammonia
plants produce waste streams of high-content CO₂ that are reutilised
in the production of downstream products. The analysis found that the overall CO₂
content of these available “high-content” streams was in excess of the quantity
of CO₂ currently reused industrially.

There are many useful valuable products into which CO₂
could be incorporated, including urea, inorganic carbonates, methanol and
salicylic acid. Potentially, CO₂ could also be reused in enhanced
oil recovery. Ideally the allocation of the available CO₂ streams
should be done taking into account the techno-economic efficiency and
environmental and social impacts. A few accordingly-suitable CO₂-consuming
plants were added to the input-output material flow network model.

This enhanced model was used to investigate the optimum means of
reusing as much as possible of the CO₂ produced, took into account
economics, environmental impact and the transportation of CO₂. Notwithstanding
that the development of new CO₂-consuming plants would need
increased capital investment, this input-output analysis suggests revenue could
be profitably realised from CO₂-derived products. Nevertheless, ultimately
to significantly reduce CO₂ emissions, in addition to the
high-content CO₂ sources, less attractive flue-gas generated CO₂
emissions and suitable separation processes need to be incorporated into the
network.  Thus attention needs to be directed toward strategies, which enhance
the nascent industrial symbiosis, for appropriately allocating the CO₂
in these low-concentration waste-streams amongst potential consumers.

¹ Knoema
World Data Atlas. (2018). “Trinidad and Tobago – CO₂ emissions per
capita”. [retrieved 01/04/2019]. Available from:
https://knoema.com/atlas/Trinidad-and-Tobago/CO2-emissions-per-capita

² UNDP,
Factor CO₂. (2014). “Projection of the Business as Usual (BaU) and
measures scenarios of carbon emissions for the electrical energy generation,
industry and transportation sectors”. Port of Spain, Trinidad and Tobago