How to plot an energy map for savings

Peter Garforth says balance carbon-cutting and cost-savings priorities by understanding your data

By Peter Garforth

The recent agreements at the Paris Climate Conference surprised many observers. More than 190 countries accepted challenging carbon targets aimed at limiting atmospheric warming to an average of 1.5 degrees above preindustrial levels. In a first, these negotiated targets were actively supported by major corporations as well as environmental groups. At the same time, the world is experiencing exceptionally low prices for oil, gas, and coal. In some cases, prices are so low as to be causing significant market disruptions and restructuring. The juxtaposition of these two pressures is, to say the least, making the industrial energy manager’s job interesting.

Dramatically reducing the carbon footprint of an industrial site demands a multidimensional longer-term strategy that will include eliminating energy waste, increasing process efficiency, and rebalancing the energy supply portfolio to a lower-carbon mix. Maximizing the benefits of current low energy prices also demands a multidimensional strategy.  This tends to put less short-term emphasis on efficiency and waste elimination and focus instead on tactically rebalancing the supply portfolio to a lower-cost mix.

Priorities will move over time and will need to be constantly adjusted based on changing legislative frameworks, market pricing, and production fluctuations. History tells us that low fuel prices may not last forever, with the added wrinkle that pressure to decarbonize the energy system may make the past a bad predictor of the future.

The bottom line is that the energy manager is more and more likely to have to manage structural carbon footprint reduction and tactical cost reduction simultaneously. The trick will be to find an optimum balance between the two.

Achieving this balance will require a clearer-than-average understanding of the way energy flows through the site. At a minimum, a clear energy map showing an overview of the sources, major uses, and waste of different energy types in a typical recent year must be developed. This overview should show energy use, energy-related costs, and carbon flows. It also needs to reach back up the electricity and water supply chain to include conversion and transportation energy uses.

Of course, energy, carbon, and cost flows vary continuously. Changing production volumes and product mix will have significant impacts. Market prices and utility contract conditions will change. Carbon legislation will directly or indirectly affect the cost of energy. A site’s decisions about efficiency and possibly on-site electricity generation will have major implications.

Creating a representative energy map, usually in some form of Sankey diagram, gives clarity to the energy information we should have but rarely do. To develop a pathway to a systematic reduction of a site’s carbon footprint while tactically managing cost, the energy manager needs regularly updated energy, carbon, and cost flow maps.

The moment a representative energy map has been produced, the next questions should revolve around metering and data capture. The basic questions are simple: Are meters available to measure the energy flows at least at the level shown on the site-level Sankey diagram? Is there necessary data in the metering system to present flows of energy-related carbon and cost? Is it possible to flexibly visualize energy carbon and cost flows over different time intervals and under different operating conditions?

If, as is typically the case, the answers are “no,” the immediate steps should be to plan, budget for, and implement a comprehensive metering system that tracks major energy flows across the plant. In the real world, many of the necessary metering points are being monitored by some form of sub-meter or control systems. What’s lacking is a sub-metering and visualization plan to complete the metering and tie it all together.

It’s not good practice to spend too much time and effort on individual energy initiatives if their impact can’t be assessed against the overall driving energy priority – to reduce carbon while optimizing cost. Reluctance to invest in comprehensive high-level metering systems is diminishing but by no means disappearing. The idea that investing in metering doesn’t improve efficiency is as flawed as the idea that investing in accounting doesn’t improve profit.

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