News & Media

SEI links powerful water, energy and climate change mitigation planning software tools to help policy-makers grapple with ‘nexus’

Attention: open in a new window. Print

Thursday, 30 August 2012 14:45

Download the press release (PDF: 86kb)


The Water Evaluation and Planning (WEAP) and Long-range Energy Alternatives Planning (WEAP) systems are already used by thousands. Now they connect easily for more sophisticated analyses of the tradeoffs required to supply drinking water, feed the world and provide energy for all.

Climate, water and energy are intricately linked, so choices in any one sector can often reverberate across the others. To achieve the best possible outcomes, policy-makers need to understand the changing dynamics in each sector as well as cross-sector interactions and tradeoffs – the so-called “nexus”.

Thanks to extensive scientific research and analysis, the nexus framework is now fairly well understood. Yet applying it in practice has been difficult because of the lack of usable quantitative tools. Now the Stockholm Environment Institute is making such a tool available – free of charge for developing nations.

For two decades, SEI’s U.S. Centre has offered and continuously improved software tools to help planners and decision-makers envision future scenarios under different climate, development and policy conditions:

The Water Evaluation And Planning (WEAP) system is used in 170 countries worldwide for integrated water resources management and planning at a range of spatial and temporal scales. WEAP models both water demand – and its main drivers – and water supply, simulating real-world policies, priorities and preferences.

The Long-range Energy Alternatives Planning (LEAP) system, used in more than 190 countries, is a powerful, versatile software system for integrated energy and greenhouse gas mitigation planning. It is widely used for energy assessments and Low Emission Development Strategies (LEDs), and has been applied in dozens of National Communications on Climate Change to the United Nations.

In a two-year project funded by the U.S. National Oceanic and Atmospheric Administration (NOAA) Sectoral Applications Research Program, WEAP developer Jack Sieber and LEAP developer Charles Heaps worked together to link the two tools to allow users to model evolving conditions in both water and energy systems and examine cross-sectoral impacts of different policy choices.

SEI unveiled the linked tools at a side-event today at World Water Week in Stockholm.

“Both WEAP and LEAP already have thousands of users who trust and rely on them,” says Heaps. “This is why we chose to link them rather than build a new tool: We hope it will better meet the needs of users in both realms, and foster vitally important cross-sector collaboration.”

Demand for integrated analytical tools has been growing amongst WEAP and LEAP users, especially in the context of resource scarcity and uncertainty about future climate change. For regions that rely heavily on hydropower, energy security depends on water availability. Thermal power plants also require water, for cooling. And the water sector requires a great deal of energy to treat and move water.

“In many settings, water and energy planners are recognizing the potential synergies and constraints between the two sectors, and seeking to work together to address them,” says David R. Purkey, who directs the Water Group at SEI’s U.S. Centre. “In California, for example, a Water-Energy Team has been created to identify potential points of connection between the agencies that oversee water and energy planning. They are very interested in deploying the WEAP-LEAP framework to support their effort. The World Bank is also launching an initiative to bring its water and energy investment planning teams together to ensure decisions made in both sectors complement each other. They plan to deploy WEAP-LEAP as part of this new initiative.”

SEI is actively encouraging both WEAP and LEAP users to take advantage of the new linkage, which allows them to easily exchange key model parameters and results. For example, LEAP users can now import water availability projections from WEAP to see how much hydropower they can count on in any given month – and how much energy they’ll need to supply from different sources. Similarly, LEAP can help WEAP users explore the energy and GHG emissions implications of desalinating seawater to meet growing urban demand.

By presenting the linked tools at World Water Week, Purkey says, SEI hopes to encourage even more people to start using the software and put the “nexus” theoretical frameworks into practice.

“Scientists have made a compelling case that we need to make connections across sectors, to address the links and feedbacks between them,” Purkey says. “Now it’s time now to roll up our sleeves and do the analysis in real-world settings. Using WEAP and LEAP together, we can better allocate resources and find development paths that will yield the greatest benefits for human well-being, economic security, and sustainability.”

Johan L. Kuylenstierna, executive director of SEI, says the WEAP-LEAP integration exemplifies a key part of SEI’s mission: to provide robust, science-based tools to help decision-makers make smarter choices.

“SEI can play an important role in helping governments envision what could happen with major economic sectors in the next 30 years, and what they can do about it,” Kuylenstierna says. “What will happen with energy? What will happen with agriculture? How will that affect water resources, and how can we mitigate negative effects? The WEAP-LEAP integration shows how we can bring sectors together so they can communicate and start planning together. That is crucial for a sustainable future.”

SEI distributes WEAP and LEAP free of charge to governments, universities, and not-for-profit organizations in the developing world.  Consulting companies, utilities and other businesses can also access the tools through affordably priced licensing arrangements. To learn more or to download WEAP, visit To learn more or download LEAP, visit

We have also compiled a factsheet on the WEAP-LEAP linkage, and a policy brief describing an application of the tool, to examine the energy and climate implications of desalination in Southern California.

For more information, please contact:
Marion Davis – Communications Manager, SEI-US
This e-mail address is being protected from spambots. You need JavaScript enabled to view it    +46 73 707 8553 (in Stockholm) or +1 617 245 0895 (U.S. callers)

Anna Löfdahl – Press and Communications Adviser
This e-mail address is being protected from spambots. You need JavaScript enabled to view it   +46 8 674 7693 (in Stockholm)

David R. Purkey – U.S. Water Group director
This e-mail address is being protected from spambots. You need JavaScript enabled to view it    +46 73 460 7458 (in Stockholm)

Share this page:
Facebook MySpace Twitter Digg Delicious RSS Feed