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Heat Recovery: the Unsung Hero on the Road to Net Zero

Efficiency remains key in a rapidly changing world

Tim Kraemer, Steam Business Development Director GESTRA
4 minute read

As the year unfolds, businesses and society alike face many challenges and uncertainty. The energy markets continue to remain volatile, with conflict in Europe having a marked impact on energy security around the globe. And, we are already seeing the effects of climate change, with unpredictable events occurring more and more. 

What is certain is that to achieve our universal aim of reaching net zero targets, a determined focus on innovation and action will be needed. Businesses are already taking the lead, realising that there is more to do, but less time to meet these goals.

Echoing the efforts of forward-thinking businesses, governments too are beginning to rise to the challenges ahead. This year sees the EEG 2023 come into force in Germany (an amendment to the Renewable Energy Sources Act1). Its aim is for 80% of the country's electricity consumption to come from renewable energy by 2030, and for power generation to be virtually free of greenhouse gases (GHG) by 2035.

There is also a new German Energy Efficiency law currently being considered by the Federal Government2. If passed, this would require companies that consume more than 10 Gigawatt hours (GWh) of energy per year to implement energy management schemes. Smaller companies using 2.5 GWh will have to conduct energy audits, whilst all companies must either avoid waste heat in production processes or use it themselves, if economically feasible.

It is not only Germany that views efficiency as critical to a potential net zero future. Last September, the Biden-Harris administration in the US published its Industrial Decarbonization Roadmap. As in Germany, around 30 per cent of industrial process heat requirements in the USA are accounted for by steam production.

Energy efficiency is a foundational crosscutting decarbonization strategy, and it remains the most cost-effective option for near term GHG emissions reductions
Industrial Decarbonization Roadmap, U.S. Department of Energy

That we are seeing the world's largest greenhouse gas emitters - China, the US, and the EU - take efficiency as a key factor in reaching net zero is a hugely positive sign. Yes, it is only one factor in that journey, but it is a vital, ongoing part of the process.

As the deadlines to mitigate climate change grow closer, we will undoubtedly see other levers play increasingly critical roles. The electrification of processes using renewable energy, and the use of hydrogen as fuel and feedstock will all play important roles but will take time to develop. By doing more with less, which is effectively the case with efficiency, we'll accelerate change whilst we wait for new technologies to emerge.

Efficiency in Practice: Heat Recovery in your boilerhouse

A major benefit to focusing on efficiency is that it involves action, now, not tomorrow, and without major changes to infrastructure. The case for improving efficiency in steam systems could not be clearer. Steam remains vital to many processes and is the most significant end-use of energy in the industrial sector. However, in our experience, many businesses are not aware of the untapped opportunities to improve steam's efficiency.

At the core of any steam system is the generation of steam, and whatever your current fuel, that will most likely come from a boiler. All boilers witness continuous evaporation as part of their normal operation. This gradually increases the number of dissolved solids inside, which has to be managed to avoid damage both to the boiler and the connected steam system.

The usual way to deal with this is something called boiler blowdown. This is further divided into two categories: bottom blowdown (also known as intermittent blowdown), and continuous blowdown. Either method effectively blows through any unwanted deposits by releasing some of the boiler's capacity. Where this is treated simply as a necessary operation, with no attempt to recover the heat and water involved, it is a significant waste of energy.

But, particularly with the larger volumes involved with continuous blowdown, this energy may be captured and used. Naturally, the specific nature of a steam system determines the potential for recovery and energy savings, but even in a simple heat recovery circuit, the payback period could be as little as a few months.

Where more sophisticated circuits are developed (as in the diagram below), flash steam and blowdown heat are used to heat and deaerate the feedwater, annual savings can run into the tens of thousands. And that's against a modest investment.

Schematic diagram of a blowdown flash installation with receiver

Schematic diagram of a blowdown flash installation with blowdown receiver

Explore how heat recovery can support your Road to Net Zero


Heat Recovery could save 15% of energy consumption

Given that the average lifespan of a steam boiler might be in the 20-30 year range, maximising your efficiency by recovering heat from boiler blowdown is both sensible and cost-effective. Of course, going on to investigate the entire system, and optimising for condensate recovery, insulation, and the many efficiency measures available is the logical next step. Dena, the German Energy Agency, estimate that tackling heat recovery could reduce energy consumption for steam and hot water generation by an average of 15 per cent.

As new technologies emerge, future options may become viable. It might be that within a few years, you will have the option to retrofit the boiler, so it can use renewable electricity to create steam. But using blowdown to ensure its smooth running will still be needed, and heat recovery will still impact its efficiency and sustainable operation.

It also makes perfect business sense. As the largest economy in Europe and its largest GHG emitter, Germany is ideally placed to spearhead this charge. Our track record in innovation and engineering is respected around the world. Building on this to adapt and positively change our processes will help define us as a leading provider of solutions to help combat climate change.

At GESTRA, we have been focused on your steam system’s performance and efficiency for over 120 years. We are here to help your business navigate the energy transition, using our expertise and experience to keep the benefits of steam for the future.

¹: Development of renewable energies | Federal Government (bundesregierung.de)
²: Germany moves ahead with energy efficiency law, amid ongoing EU talks – EURACTIV.com

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