Renewable Energy Powered Ships
Is it possible in the near future?
By Swapnil Maiti and Surojit Saha
Transportation through water is mainly utilized by freight transport. Maritime transport actually accounts for roughly 80% of international trade, as opposed to other modes of transportation, according to UNCTAD in 2020. Merchant shipping is the lifeblood of the world economy, carrying 90% of international trade with 102,194 commercial ships worldwide.
On the data based on 2016, shipping contributed to 1.7% of the World’s CO₂ emissions, compared to 1.9% for aviation and 11.9% for road transportation. Maersk — The world’s largest shipping company, released 36.5 million metric tons of CO₂ from its cargo ships alone, according to a study in 2019. Maritime transport is yet to introduce sustainability as opposed to other modes of transport.
Let us look into some of the advancements made so far.
Attempts towards Reduction in Conventional Fuel Consumption
There have been many attempts towards a reduction in fuel consumption for cargo ships. Most primitive ones being lowering transport speeds and introducing bulbous bow in ships. Others are as follows:
Hybrid Marine Power Systems
Hybrid Power or Hybrid Marine Power (HMP) systems lower fuel consumption, reduce airborne pollution and are energy efficient. Eco Marine Power along with a group of partner companies are developing the patented Aquarius MRE which is an advanced integrated system of rigid sails, solar panels, energy storage modules & marine batteries that will enable ships to tap into renewable energy by harnessing the power provided by the wind and sun.
Still, this technology is not applicable for cargo ships as they do not allow the space for such setups because of cargo loading.
Hydrogen Fuels
Hydrogen fuels are expensive but they are a viable option to look forward to. Countries like Norway and Japan have already started investing in this market and aim to successfully decrease the use of biofuels (as the use of biofuels indirectly promotes deforestation) to 0% by 2050.
Wind Energy
Harnessing wind energy is a tough task for cargo ships as they won’t allow the installing of wind power integration systems as they take up too much space.
A striking advancement has been made in utilizing wind energy through Flettner Rotors. They take up minimum space and returns and an appreciable amount of energy. The rotors are controlled by a computer which requires little to no input from the ship’s crew.
A Flettner rotor is a smooth cylinder with disc endplates that is spun along its long axis and, as air passes at right angles across it, the Magnus effect causes an aerodynamic force to be generated in the direction perpendicular to both the long axis and the direction of airflow.
A study has shown that Flettner rotors have saved 8.2% of the total fuel consumption in 2018–2019.
Simulation on Model Ships
A combination of possible sustainable energy methods has been applied on concept ships and their performance has been monitored using computer-aided simulation and analysis. The following components were included in the power structure:
- Flettner Rotors
- Vertical axis wind turbines — operating at the reference wind speeds of 3 m/s as the minimum wind speed, 12 m/s of nominal wind speed and 26 m/s cut-off speed.
- Photovoltaic Solar Panels — covers the whole weather deck, with a nominal power of 460W each, and a panel efficiency of 21.3%.
- Dual-Mode Propeller/Hydro Turbine — which uses flowing water to generate power.
Result
The first study case analyzes the Barcelona–Tunis route with a minimum speed of 5 knots. The average power consumption of the systems onboard was 729 kW, while the average power generation was 149 kW.
At the end of the voyage, the energy balance showed that 55702 kWh were required in addition to the available renewable sources at sea. This is equivalent to 446 fully charged commercial marine batteries of 125 kWh each and a weight of about 713 tons, considering that each battery weighs 1.6 tons
Conclusion
With the current advancements in renewable energy sources, we are expecting more research in this area, which may lead us to perfectly sustainable transport systems. Applying this technology to maritime transport — on which the world economy is strongly dependent, is our hope for a sustainable future, considering the environmental crisis that we are currently facing.
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