06/02/2013 08:08 GMT | Updated 07/04/2013 06:12 BST

What is the Water-Food-Energy Nexus?

The extent of the inter-connections between the water, food and energy means that issues such as water scarcity and food and energy security cannot be addressed in local silos. As global populations continue to grow, addressing the relationship between water, food and energy is only going to become more pertinent.

Those of you who have visited these pages before may have come across other blogs in which I talk about the water food energy nexus.

But what exactly is the nexus, and why is it so important?

When we look at water, food and energy as resources, it is impossible to separate them - we need water to grow food, we need water for energy, we need energy to grow food, we need energy to treat and move water, and we need land and agricultural outputs for some of our energy provision.

The problem is that the resources are very rarely treated or managed in a way which appreciates their interconnections. Business decisions and policies are made in isolation - sometimes with unintended consequences. For example, in the pursuit of renewable energy, land might be dedicated to growing biofuels leaving the local population unable to grow the food they need to survive, and precious water sources depleted. Or, an agriculture ministry might determine to increase the amount of land under irrigation in order to grow food for its population, but do so at the expense of already-stretched water sources.

The nexus doesn't always need to be negative and brewing beer is a useful demonstration. We rely on large quantities of high quality water in order to make beer. Therefore water quality and availability are issues that matter deeply to us. Our approach to water management starts with making our breweries as water efficient as we can - we're aiming to use 3.5 litres of water to make 1 litre of beer by 2015, which will represent a 25% improvement on 2008. But by using less water, we reduce the amount of energy we use to pump, heat and treat it. And where we have developed more energy-efficient ways of boiling the wort (which eventually becomes beer), less water is lost through evaporation. In some breweries we're using agricultural waste, such as rice husks and biomass from stalks, sawdust and groundnut shells. This is renewable energy, but it also brings additional income to local farmers, allowing them to profit from the by-products of food production.

Efficiency improvements are always the first step for companies, both within their own boundaries and then with their supply chain partners - and more and more companies are benefiting from managing their resources in a joined-up way. But that alone is not enough - the private sector and finance communities also need to encourage governments to address the need to set resource policy in an integrated way, in order to maximise the economic and social value; and to manage the inevitable trade-offs which will take place.

This is an issue that needs collaboration and collective actions, it's an ongoing discussion and I'd be keen to hear your thoughts and ideas.