Energy Consumption of a Seawater Desalination Plant

Currently, seawater desalination plants are being used all over the world, mainly in regions where water resources are not sufficient for human needs. However, it should be noted that the energy consumption involved in the process can have adverse impacts on the environment, especially the marine life. In addition, the reuse of water for agricultural irrigation can also be a problem, especially when we consider the environmental impact of using energy to pump the desalinated water into aquifers.

What is Energy consumption in Seawater Desalination Plants?

Seawater desalination is considered one of the most promising methods for the production of fresh water. And, it is not expensive compared to other means of producing drinking water. Also, an accurate and systematic evaluation can enable sustainable and energy efficient desalination.

The energy consumption of seawater desalination has decreased in recent years. This decrease has been attributed to improved membrane technologies and energy recovery systems. As a result, energy use is a relatively small factor in the total cost of a plant.

For a large-scale plant, the power consumption of a seawater desalination process is less than three kilowatt hours per metre squared. This represents a 90% reduction in energy use over the last 40 years.

In addition to electricity, heat is also an important energy source. Heat engines, such as CCGT plants, have achieved higher levels of energy efficiency. While the energy efficiency of seawater desalination hasn’t quite reached this level, heat engines have the potential to do so.

There are several different types of energy sources used in seawater desalination. These include electric power, natural gas, diesel fuel, coal, and biogas. Electricity is the most common form of primary energy used in the process.

Power is required to move the seawater, as well as to maintain the high pressure of the processing system. High pressure can reach 70 times the atmospheric pressure, and thus requires high-powered pumps and a huge amount of equipment. It is also possible to co-generate electricity and thermal heat. Although these types of desalination processes are more energy intensive, they are more effective in achieving a significant amount of fresh water.

How does Desalination Plant Works?

Desalination is a process that produces fresh water from seawater by removing salt. It is often considered a solution for drought-stricken areas, where freshwater is scarce.

The process involves taking seawater and forcing it through a reverse osmosis membrane. After this process, the water is treated and becomes a potable resource.

Reuse of Desalinated Water for Agricultural Irrigation

Desalination technology for agricultural irrigation plays a key role in addressing water scarcity. During the recent decades, the world has faced a shortage of fresh water. This has led to a rise in the use of non-conventional water sources. In particular, seawater is an important source of water.

Agricultural irrigation with desalinated water has advantages over other water sources. The first is the ability to produce water without using electricity. It also helps to reduce labour costs. Furthermore, the water produced by desalination plants can be reused for agricultural irrigation.

Compared to other water resources, the use of desalinated water for agricultural purposes has less adverse effects on soils. The energy requirements for desalination for agriculture can be reduced by using a renewable energy source. The cost of energy can be up to 75% of the total operational costs of a seawater RO desalination plant.

The use of treated wastewater for agricultural irrigation is another possibility. It can help to provide the necessary nutrients for plant growth. Also, the health risks associated with treated wastewater can be minimized. Treatment processes for water can involve a number of steps, including removing micro and nano-pollutants.

Other factors to consider are the amount of dissolved solids and the salinity level. These must be treated and blended with the desired amount of nutrient ions. Generally, desalinated water has sufficient amounts of minerals, sulphate and calcium.

Reuse of desalinated water for agricultural irrigation is a positive option in regions where there is water scarcity. However, the environmental, social and economic impacts of the process must be assessed.

The Bottom Line

Desalination plants pump out millions of gallons of seawater each day. By implementing new methods and reducing the amount of wastewater that flows into the ocean, the number of marine organisms killed can be minimized with the use of desalination plants. Also, new techniques will make renewable energy powered desalination plants more competitive.