Marine renewables represent a promising and innovative alternative source for satisfying the energy demands of growing populations while reducing the consumption of fossil fuels. Most technological advancements and energy yield assessments have focused on promoting the use of kinetic energy from tidal streams with flow velocities higher than 2.0 m s⁻¹. However, slower-moving flows from ocean currents are recently explored due to their nearly continuous and unidirectional seasonal flows. In this study, the potential of the Yucatan Current was analysed at nearshore sites over the insular shelf of Cozumel Island in the Mexican Caribbean. Field measurements were undertaken using a vessel-mounted Acoustic Doppler Current Profiler (ADCP) to analyse the spatial distribution of flow velocities, along with Conductivity-temperature-depth (CTD) profiles as well as data gathering of bathymetry and water elevations. Northward directed flow velocities were identified, with increasing velocities just before the end of the strait of the Cozumel Channel, where average velocities in the region of 0.88–1.04 m s⁻¹ were recorded. An estimation of power delivery using horizontal axis turbines was undertaken with Blade Element Momentum theory. It was estimated that nearly 3.2 MW could be supplied to Cozumel Island, amounting to about 10% of its electricity consumption.

Existing installations of tidal-stream turbines are undertaken in energetic sites with flow speeds greater than 2 m/s. Sites with lower velocities will produce far less power and may not be as economically viable when using “conventional” tidal turbine designs. However, designing turbines for these less energetic conditions may improve the global viability of tidal technology. Lower hydrodynamic loads are expected, allowing for cost reduction through downsizing and using cheaper materials. This work presents a design methodology for low-solidity high tip-speed ratio turbines aimed to operate at less energetic flows with velocities less than 1.5 m/s. Turbines operating under representative real-site conditions in Mexico and the Philippines are evaluated using a quasi-unsteady blade element momentum method. Blade geometry alterations are undertaken using a scaling factor applied to chord and twist distributions. A parametric filtering and multi-objective decision model is used to select the optimum design among the generated blade variations. It was found that the low-solidity high tip-speed ratio blades lead to a slight power drop of less than 8.5% when compared to the “conventional” blade geometries. Nonetheless, an increase in rotational speed, reaching a tip-speed ratio (TSR) of 7.75, combined with huge reduction in the torque requirement of as much as 30% paves the way for reduced costs from generator downsizing and simplified power take-off mechanisms.

The Philippine Biofuels Act of 2006 (RA 9367) requires commercial diesel fuel to be mixed with Coconut Methyl Ester (CME) in accordance with the Philippine Clean Air Act of 1999 (RA 8749). As of 2015, the blend percentage is at 2% CME v/v, contrary to the scheduled 5% as stipulated in the biofuels act. Researches done locally showing the performance and emissions of CME-fueled engines are few and thus the basis for the CME percentage increase is still questionable and hampers the drive for the further implementation of the policy. The study investigates the influence of varying percentages of CME blends (2%, 5%, 10%, 15%, 20% v/v) to the performance and emissions of a heavy-duty turbocharged common rail direct injection (CRDI) engine. The engine is run at steady state at partial load (50Nm and 250 Nm) and at near full load (500Nm). Each run is set at three pedal positions, α (25%, 50% and 60%), controlled directly from the engine control unit. Results show a significant increase in brake specific fuel consumption at higher percentages of CME with a maximum of 3.16% at higher loads and at 25% α. Nitrous Oxides (NOx) is of particular importance in dealing with biofuel methyl esters and is found to significantly increase at higher percentages of CME with a maximum of 8.91% at higher loads across all α. Carbon monoxide (CO) and hydrocarbons of diesel (HCD) were found to not be significantly affected by the usage of CME. Nevertheless, there is still some potential in the usage of CME due to the fact that power and torque is still achievable at the expense of higher fuel consumption; but with the opportunity of being self-sufficient as a coconut-producing country.

Indoor exposure to particulate matter (PM) depends on ventilation-driven transport, yet sensor placement in real rooms is often based on limited point data. This study develops and experimentally validates a transient CFD framework, using RANS airflow coupled with Lagrangian discrete phase tracking, to map PM_2.5 and PM₁₀ in a full-scale 2.0 × 3.0 × 2.5 m bedroom with a fixed, non-oscillating pedestal fan and an open window. Airflow was verified by grid independence and validated against 10-point velocity measurements (RMSE = 0.108 m·s⁻¹). Incense experiments (≈31 min burn) provided PM time series over the first 60 min at 16 locations on two heights; emission rate, burning time, and air-change rate (1.96–5.39 ACH) were calibrated so that accepted models achieved aggregate R² > 0.90. Spatial mapping on a 0.5 m grid shows that PM behavior is governed primarily by airflow-defined accumulation pockets rather than by source proximity alone. A near-source region consistently captured strong early-time peaks, whereas remote low-exchange pockets remained elevated during the decay phase. For PM_2.5, the most persistent hotspot is a ceiling-adjacent recirculation pocket, while for PM₁₀, gravitational settling shifted the dominant hotspots toward floor-layer, low-velocity regions. An exposure score combining normalized peak and time-averaged concentrations, interpreted together with particle-track persistence metrics, distinguished transiently traversed regions from true retention pockets. The results show that sensor placement should follow the monitoring objective: near-source regions are more responsive to peak events, ceiling pockets are more suitable for persistent PM_2.5 monitoring, and floor hotspots are more critical for PM₁₀. No single fixed sensor location adequately represents both particle sizes in the present bedroom and ventilation configuration.

This paper presents the results of a two-phase Philippine study to determine the actual mileage (km/liter) of in-use diesel and LPG (liquefied petroleum gas or Auto-LPG) public utility jeepneys plying two separate Metro Manila urban routes using both on-road and chassis dynamometer tests. Measured average load factor in on-road tests was 60-70%. Dynamometer tests at 100% load factor utilized drive cycles derived from on-road speed data. A “diesel equivalent mileage” of actual LPG mileage, deemed indicative of LPG “fuel energy conversion efficiency” relative to diesel, was calculated (based solely on fuel heating values and densities) for comparing actual mileage from both fuels. The LPG actual mileage in both on-road and laboratory tests was lower than diesel mileage. In on-road tests, the LPG actual mileage was lower than diesel actual mileage by about the same percentage LPG heating value was lower than diesel’s per liter of fuel. The LPG diesel equivalent mileage was also about the same as diesel actual mileage so that fuel conversion efficiencies of both jeepney types were deemed similar. In chassis dynamometer tests at 100% load factor, the LPG diesel equivalent mileage was lower than diesel actual mileage. This implied that in addition to the effect of lesser LPG heating value per liter, the LPG jeepneys had lower energy conversion efficiencies than diesel at load factors higher than experienced in the on-road tests. Optimization of the LPG jeepney via tuning and/or powertrain configuration is suggested especially if deployed at higher load factors. The amount of financial incentives, e.g. fuel pricing, to promote LPG jeepneys should take into account its comparable on-road fuel conversion efficiency to diesel and generally accepted better emissions.

Offshore wind development in the Philippines remains at a standstill owing to the relatively high cost of the technology despite the government’s ambitious goal to produce 19–50 GW by 2050. Previous studies have shown that bottom-fixed turbines can be utilized to reach the lower end of the production target. Still, most potential can be achieved in greater depths where floating turbines are more appropriate. Therefore, this study performs a techno-economic assessment for floating offshore wind energy using global information system (GIS) software to analyze the technical and economic potential of floating offshore wind energy in the Philippines. Data from the Global Wind Atlas was used to obtain the technical potential of sites that may be used for floating offshore wind turbines. Exclusion zones are set up according to distance from shore, marine protected areas, oil and petroleum sites, shipping lanes, and submarine cables. Factors on distance to shore, port, and substation, as well as natural hazards and bathymetry, are considered according to a weighted analytic hierarchical process. The net present value (NPV) of each potential site is then calculated by considering the capital, operational, and decommissioning cost of a site at a 6% interest rate and 25 years of operational life. Results show that there is a total potential of 813 GW that can be produced from a total of 20 non-contiguous sites. However, the current feed-in tariff (FIT) rate of 8.53 Php/kW is insufficient to make any sites profitable as all NPVs are negative. The breakeven prices can guide the Philippines government to set an appropriate rate at a minimum of 10.14 Php/kW.