Humans have relied on limited freshwater resources to sustain our life, but we ignored an almost infinite supply of seawater - a resource that could turn land that was unfarmable into crop fields and solve the food crisis. As populations in water-stressed areas rapidly grow, the demand for food grows along, while climate change exacerbates the situation as well. According to the United Nations, in Sub-Saharan Africa, the percentage of people who have access to safe water only grew from 17.9% to 23.7% since 2000. And, by 2030, about 70 to 250 million people in Africa could be living in areas that face high water scarcity.
Distribution of total world installed capacity by type - Source
Desalination as opportunities
Desalination of seawater can play a vital role in combating the challenge of water scarcity. The total water demand is dominated by agriculture (70%), followed by industrial (21%) and domestic (9%) use (Kumar et al, 2018). The use of low quality water can reduce crop yields and cause environmental damage to soils and aquifers. This is where seawater desalination comes in as an alternative to increasing water supply beyond the natural hydrological cycle (Shannon et al, 2008). Studies have also shown that irrigation with desalinated water can significantly increase the yield of crops as the soil is richer with salinity and boron (Diaz et al, 2013). Domingo (2013) further explored into desalination, the use of desalinated seawater can benefit the agriculture sector - there will be no requirement for post-treatment, reducing labour requirements and reducing costs of production.
Desalination in Africa
In Africa, there is already an example of using seawater to help with the agriculture sector - The Seawater Greenhouse Project in Somaliland. Noticing the planet’s freshwater is limited, the project harnesses the two things the earth has ‘infinite’ supply: seawater and sunlight, to help Somaliland to grow food in the middle of the desert. Just like the name, the project incorporates the use of a greenhouse in creating a humid oasis for vegetables, fruits and plants to grow. The greenhouse uses a pad and fan technology, air is pushed through the soaked pads using the power of the fan, creating water vapour that controls the humidity of the greenhouse, which maintains the room temperature at around 15 degrees.
Photo of the Seawater Greenhouse Project - Source
In the greenhouse, saltwater is also used. When the saltwater passes through the pads, the salinity of the water decreases as the salt is being separated from the fresh water - the remaining high salinity water called brine, is used in the greenhouse as a form of cooling. Different from other traditional methods for desalination, which are known to be costly and damaging the ecosystem, the use of seawater greenhouse is more eco-friendly. Unlike the traditional methods where leftover brine is dumped back into the ocean, leftover brine produced in the greenhouse is made into salt.
Challenges Ahead
However, it is inevitable to see the challenges ahead of the use of desalinated water. Firstly, the cost is still very high compared to other conventional resources of water, this is reflected by including all the net costs counting energy, labour, chemicals, operations, maintenance and so on. For developing nations in Africa, the cost of using desalinated seawater might become unbearable for the government (Kumar et al, 2018). Moreover, the use of a greenhouse is just one way of utilising seawater, the most common strategy still remains as desalinating seawater using industrial plants, where they can only be set in countries along the coast. Not to mention the cost, the landlocked countries in Africa are the ones that face the most risk, and the setting of an industrial plant will not benefit them. Transporting freshwater can be an option, but the cost will be very high.
Just like any other intervention, the implementation process faces a lot of obstacles other than just economic factors, but environmental, social and political as well. However, it is believed that desalinating seawater would combat the issue of both water and food insecurity.
You brought attention to the fact that desalination plants are only viable at the moment along the coast. Thus, with many African countries being landlocked, do you think the potential of desalination plants to tackle food insecurity is limited?
ReplyDeleteHi Claudia, thank you for raising this point!
DeleteIn my opinion, the landlocked countries are definitely in a more difficult position to tackle food insecurity through desalination. However, in my previous blogs I have mentioned that there are other solutions such as groundwater and GMO, which can be a better solution to the landlocked countries.