By Tomer Efrat
For many years, desalination and water treatment were considered an integral part of ever-growing sustainability and environmental awareness. Water, as one of the most vital natural resources on Earth, is getting less and less abundant for a variety of reasons, and it is clear we must implement ways to protect our available freshwater sources and generate new ones in places where water is scarce.
Seawater desalination, which is widely used globally, is the most viable solution for generating sustainable, long-lasting freshwater sources. However, despite the remarkable advancements in seawater-desalination technology and its cost-effectiveness, seawater desalination comes at a cost to the environment, like other manufactured solutions. As we wish to expand the scope of seawater-desalination plants, the water industry keeps investing in research and development to improve seawater desalination’s economic viability and, recently, its sustainability prospect. At first glance, expanding seawater desalination and mitigating its impact seem like different, even conflicting, goals, but when approached correctly, there is no contradiction, but a shared drive.
Implementing a solution that reduces power and chemical consumption, increases reverse osmosis membrane life span, and utilizes greener energy will improve a desalination plant’s sustainability level. However, surprisingly enough, no gold standard unambiguously determines or even quantifies what is considered an improvement. In other words, while more and more sustainable desalination solutions emerge, no clear standard or any other tool that quantifies the environmental benefit is provided.
Measuring Environmental Impact
As you can’t manage what you can’t measure, establishing an acceptable method of calculating the environmental impact of seawater desalination would allow a better understanding of how to reduce that impact. Additionally, by presenting a precise value of the environmental impact, we can provide both regulators and partners a comparison of different seawater-desalination technologies based on, for example, specific carbon footprints, as an alternative approach or in addition to the obvious ones, such as capital expenditures and operational expenditures. This is a fundamental phase in which desalination companies can compete not only on their desalination plants’ specific cost or power consumption, but also on their specific carbon footprint.
In a world of limited natural resources, we must be able to provide solutions that are not based on simply shifting the environmental impact from one impact type to another, but on reducing or even eliminating it. Therefore, we must have the tools to evaluate the sustainability of each solution we develop. The most common way to evaluate the environmental impact of an industrial process is by conducting a life cycle assessment (LCA).
The Life Cycle Assessment
The LCA is a method standardized by the ISO (International Organization for Standardization) that includes a set of procedures for calculating the environmental impact associated with producing a product. It is an effective method widely applied to evaluate the environmental performance of desalination.
In most cases, an LCA is conducted to identify the greatest contributors in the production chain. It also enables comparisons of alternative technologies, energy sources, or even operation strategies to create the least environmental impact. A complete LCA of a system consists of four general phases in the product or service chain, each of which can be further broken down into substages:
- Acquisition of materials (through resource extraction or recycled sources).
- Use by consumers.
- End-of-life disposition (incineration, disposing in a landfill, composting, recycling/reusing).
The LCA itself also has four phases:
- Goal and scope definition.
- Inventory estimation of resources and waste flows.
- Environmental impact assessment that includes characterizing, normalizing, and weighting the impact in certain categories, for example, climate change, toxicological stress, and land use.
- Interpretation of the findings and uncertainty analysis to provide a better understanding of the results.
The scope defines the functional unit, the primary purpose of a system that enables comparing different systems as functionally equivalent. In seawater desalination LCA studies, the functional unit is defined as one cubic meter of product water. The boundary selection determines the processes and activities that will be included in an LCA study.
There are two main issues that require improvement when implementing seawater-desalination LCA studies. The first is the feasibility and reliability of the supporting databases, since they are not fully available to researchers. The second is the system boundary because it defines the scope of the study and considerations such as geography, regulation, and local suppliers. Uncertainty analysis is also an improvement that can strengthen LCA as an effective method to evaluate the environmental footprint of seawater-desalination alternatives.
Since some LCA parameters are of higher importance than others, and to achieve a simplified tool that will be easy to adopt, let’s examine an in-depth LCA for a large-scale industrial seawater (saltwater) reverse osmosis (SWRO) plant. Such an LCA can be used in the following ways:
- To evaluate the prominent influencers by generating a Pareto principle (80/20 rule) for seawater desalination.
- As a benchmark for comparison between different design concepts.
- As an evaluation tool for advanced and innovative green solutions aiming to improve the sustainability of SWRO plants.
Additionally, as seawater desalination is widely used as a source of fresh water, by definition it serves as a water supplier when conducting LCA for other industries, such as the mining or petrochemical industries. Thus, the results of this LCA study will also contribute tremendously to the global impact factors database.
The assessment of the SWRO process will study the full range of potential impact in a selected boundary, and will focus on the major known impact and quantify its specific carbon footprint. The assessment will be conducted by characterizing all inputs and outputs of an SWRO facility.
We must move beyond presenting concepts to improve desalination plants’ sustainability and start providing an actual, ready-to-be-implemented solution with a clear and quantifiable measurement of environmental impact.
About the author
Tomer Efrat has substantial background and experience in the water industry, including seawater desalination as well as water and wastewater treatment. Efrat started his journey with IDE in 2005, first as a process engineer in the Thermal Process department and then serving in various technological and commercial roles, including process engineering manager and director of business development, leading IDE’s water treatment activity. He climbed up the ladder to his current position – IDE’s vice president of research and development, overseeing IDE’s work in this field while reinforcing IDE’s position as a global water technology leader. Efrat is an alumnus of Recanati Business School, Tel Aviv University, and he has an Executive MBA. He also holds a B.Sc. in Mechanical Engineering from Tel Aviv University.
About the company
A desalination and water-treatment company, IDE specializes in the development, engineering, construction, and operation of thermal and membrane desalination facilities and industrial water-treatment plants. IDE partners with a wide range of customers on all aspects of water projects and delivers approximately 3 million cubic meters per day of high-quality water worldwide