Ocean Energy Now Declared As Renewable Energy

23 Aug 2019

Recently, in a decision that would give boost to the ocean energy in India, Ministry of New and Renewable Energy (MNRE) approved a proposal to declare ocean energy as Renewable Energy.
Accordingly, the Ministry has clarified to all the stakeholders that energy produced using various forms of ocean energy such as tidal, wave, ocean thermal energy conversion shall be considered as Renewable Energy and shall be eligible for meeting the non-solar Renewable Purchase Obligations (RPO).

Objectives

To accelerate and enhance support for the resource assessment and deployment of ocean energy in the country
To harness ocean energy for power generation and to overcome the barriers.

Renewable Purchase Obligations (RPO)

It refers to the obligation either to buy electricity generated by specified green sources, or buy, in lieu of that, renewable energy certificates (RECs) from the market.
The ‘obligated entities’ are mostly electricity distribution companies and large consumers of power.

Renewable Energy Certificate

REC mechanism is a market based instrument to promote renewable energy and facilitate compliance of renewable purchase obligations (RPO). It is aimed at addressing the mismatch between availability of RE resources in state and the requirement of the obligated entities to meet the renewable purchase obligation (RPO).
One REC is treated as equivalent to 1 megawatt hour.

Ocean Energy

Oceans cover 70 percent of the earth’s surface and represent an enormous amount of energy in the form of wave, tidal, marine current and thermal gradient.

Tidal Energy:

The tidal cycle takes place every 12 hours due to the gravitational force of the moon. The difference in water height from low tide and high tide is potential energy. Similar to traditional hydropower generated from dams, tidal water can be captured in a barrage across an estuary during high tide and forced through a hydro-turbine during low tide.

Issues with Tidal Energy:

The capital cost for tidal energy power plants is very high due to high civil construction and high power purchase tariff.
To trapenough power from the tidal energy potential, the height of high tide must be at least five meters (16 feet) greater than low tide.
Environmental concernsare also associated with it since it completely changes environment in this area and affects life of many ecosystems, especially for birds that rely on the tide uncovering the mud flats so that they can found food.

Wave Energy:

Regular disturbances on the surface of the water are called waves. The wave energy is a form of kinetic energy. This is used to power a turbine. Wave energy is captured from the directly from the surface of the waves produced in the oceans.

Issue with Wave Energy:

The main problem with wave energy is the fact that this energy source isn’t the same in all parts of the world, since it varies significantly from place to place. This is the reason why wave energy can’t be exploited in all parts of the world but there are many researches that work on solutions of how to solve this variability problem.

Ocean Thermal Energy Conversion (OTEC):

OTEC uses ocean temperature differences from the surface to depths lower than 1,000 meters, to extract energy. A temperature difference of only 20°C can yield usable energy.
The concept was first introduced by French engineer Jacques D’Arsonval in year 1881.

Issues with OTEC:

OTEC works best when the difference in temperature between the warm top layer and cold deep layer of the sea is around 20 °C (36 °F). This condition commonly exists in tropical coastal areas, therefore limiting its operation area.
There are several logistical issues that have prevented ocean thermal energy from really taking off. Apart, the cost of a conversion plant is enormous as the plants require an expensive, large-diameter intake pipe submerged to more than a mile into the ocean to bring cold water to the surface.

India’s Ocean Energy Potential

According to MNRE, the total identified potential of tidal energy is about 12,455 MW, with potential locations identified at Khambat & Kutch regions, and large backwaters, where barrage technology could be used.
The total theoretical potential of wave energy in India along the country’s coast is estimated to be about 40,000 MW – these are preliminary estimates. This energy is however less intensive than what is available in more northern and southern latitudes.
OTEC has a theoretical potential of 180,000 MW in India subject to suitable technological evolution.

Benefits of Ocean Energy

Renewable Energy Source: Wave energy and tidal energy both use the natural dynamics of the abundant ocean, and do not use any non-renewable fuels to generate electricity.
Clean Energy Source: They do not produce greenhouse gases or other pollution while operating, and reduce reliance on fossil fuels. There are no waste products created by ocean power generation.
Predictable Energy Source:Ocean energy for ex. tidal energy can be predicted with great regularity what the tidal tables are going to be. The same cannot be said of wind or solar energy, which can be disrupted due to simple weather changes.
Abundant Energy Source: As wave and tidal power generators are built along coastlines, there is huge potential, particularly in countries that have long coastlines. For ex. India
Low Running Costs: Though the initial set up cost is very high for these plants but once an ocean energy plant starts operating, it is anticipated that it’s running costs are quite low, especially compared to more dominant forms of power generation such as oil and coal plants, as well as nuclear power.

Way Forward

The government needs to look over the horizon at development of new technology in harnessing ocean energy and considers the various options available to support its deployment. Though deployment is currently limited but the sector has the potential to grow, fuelling economic growth, reducing carbon footprint and creating jobs not only along the coasts but also inland along its supply chains.
It is time for the government to create a clear roadmap for promotion of tidal energy as individual and hybrid technologies and like solar energy;ocean energy needs to be incentivized for its better and sustainable utilization.