ABSTRACT: This paper improves short-term forecasting models of monthly tourism arrivals by estimating and evaluating a time-series model with exogenous regressors (ARIMA-X) using a case of Aruba, a small open tourism-dependent economy. Given importance of the US market for Aruba, it investigates informational value of Google Searches originating in the USA, flight capacity utilization on the US air-carriers, and per capita demand of the US consumers, given the volatility index in stock markets (VIX). It yields several insights. First, flight capacity is the best variable to account for the travel restrictions during the pandemic. Second, US real personal consumption expenditure becomes a more significant predictor than income as the former better captured impact of the COVID-19 restrictions on the consumers’ behavior, while income boosted by the pandemic fiscal support was not fully directed to spending. Third, intercept correction improves the model in the estimation period. Finally, the pandemic changed econometric relationships between the tourism arrivals and their main determinants, and accuracy of the forecast models. Going forward, the analysts should re-estimate the models. Out-of-sample forecasts with 5 percent confidence intervals are produced for 18 months ahead.
Microalgae are a promising renewable feedstock for a wide range of biobased products, such as food, feed, chemicals, and biofuels. To commercialize bulk products from microalgae, the production costs need to be reduced, for example, by improving biomass productivities in outdoor photobioreactors. Geographical locations near the equator are considered ideal for outdoor cultivation, due to the abundance of sunlight throughout the entire year. However, at high light intensities the photosystems of microalgae become oversaturated, which limits photosynthetic efficiencies and biomass productivities. Therefore, we propose a novel V-shaped photobioreactor to capture and dilute available sunlight at low latitudes. For different V-shaped designs, we modelled the sunlight entering the photobioreactor during several days of the year and theoretically estimated the maximal biomass productivity of Chlorella sorokiniana on the island Bonaire (12°N, 68°W) assuming clear-sky conditions and light-limited growth. Our results show that theoretical biomass productivities of 38.3–50.5 g m−2 day−1 can be achieved in V-shaped photobioreactors, corresponding to photosynthetic efficiencies of 2.5–3.3%. These productivities are up to 1.4 times higher than those estimated for a flat horizontal photobioreactor, primarily due to improved light dilution in V-shaped photobioreactors. Thus, V-shaped photobioreactors present opportunities for more efficient microalgae production.