Absorption Chiller or Electric Chiller: 1,000 kW Cost Comparison

This guide is for people who choose a cooling system of roughly 250 kW and up: chief engineers, design engineers, technical directors, finance people and plant owners. The choice between a conventional vapor-compression chiller and a lithium bromide absorption chiller decides not only the purchase price but the electricity bills for the next 15–25 years. I compare both technologies without taking sides: at a typical 1,000 kW, with cheap or waste heat on site, an absorption chiller saves about RUB 1.02 million a year. Where there is no heat source, low temperatures are needed, or speed and simplicity of installation matter, the electric chiller wins. The PDF is in Russian; the key points are below in English.

What is inside the guide?

• A one-page "3-step quick choice" memo and a reference table: eight site conditions and the right technology for each.

• Five aspects of the decision, site infrastructure factors and refrigerants: why synthetic refrigerants keep getting more expensive while an absorption chiller uses water as its refrigerant.

• NCT chillers: strengths and the standard range of 260–4,396 kW, 8 types and 84 models.

• Absorption chillers: strengths, honest limitations and the four-stage working cycle on a diagram.

• Trigeneration: power, heat and cooling from a single fuel.

• Economics at 1,000 kW: annual cost, power and gas consumption, service life, cumulative costs over 20 years.

• Seven common doubts about absorption chillers, the answers, and sites where the machines already run.

• A selection algorithm: when to pick an electric chiller, when an absorption chiller, and when a hybrid.

Key takeaways

The memo reduces the choice to three steps: heat, power, time horizon. If the site has gas, steam, hot water from cogeneration or process waste heat, the absorption chiller becomes candidate number one. If grid capacity is short or the tariff is high, the absorption chiller takes load off the grid. Compare total cost of ownership over 15–25 years, not the purchase price. If at least three conditions from the top group of the table apply to your site, model an absorption chiller at the concept stage.

At 1,000 kW of cooling, the absorption system costs RUB 1.66 million a year to run, the electric chiller RUB 2.68 million. The difference is RUB 1.02 million, or 38% lower annual cost. The absorption system draws 87 kW of electrical capacity against 245 kW for the chiller, and uses 135,894 kWh a year against 382,690 kWh, which is 2.8 times less electricity. In exchange it takes 718 kW of heat and 118,054 m³ of gas a year. The calculation assumes 1,562 operating hours a year at 70% average load; on your site the figures depend on tariffs and climate.

Grid connection can cost more than the machine. A new grid connection costs roughly RUB 150,000 per kW. The 158 kW gap between the electric chiller and the absorption chiller is about RUB 24 million up front, before any equipment is bought.

An absorption chiller lasts longer and pays back the price gap. Service life is 25+ years against 15–20 for an electric chiller. Over 20 years, the operating difference of about RUB 1 million a year more than covers the higher capital cost, usually within 2.5–5 years. At small capacities, up to about 500 kW, the electric chiller really is cheaper to buy.

Heat is a resource that often goes unnoticed. An absorption chiller runs on hot water from an ordinary boiler house: 80–95 °C is enough. There are also direct-fired gas and diesel models and exhaust-gas models. In trigeneration, a gas engine turns 100% of the fuel into about 35% electricity and about 50% heat, the absorption chiller converts that heat into cooling, and fuel utilization reaches 85%.

A low coefficient of performance is not a deal-breaker. The thermal COP of an absorption chiller is about 0.75–1.9 against 3–5 for a compressor chiller, but it burns heat, not expensive electricity. The fair comparison is the cost of 1 kW of cooling in rubles.

The technology has honest limitations. Higher purchase and installation cost, more weight and a larger footprint, more complex piping and controls, and it needs an experienced designer and qualified service. It takes about 30 minutes to reach full output because of the thermal inertia of the solution. An NCT electric chiller is the choice when there is no cheap heat, no make-up water for a cooling tower, tight limits on size and weight, or a need for fast and simple installation.

The optimum is often a hybrid. The absorption chiller covers the base load on cheap heat. A peak chiller is added only where the load swings: in manufacturing and data centers.

Who is it for?

• Chief engineers and technical directors choosing a cooling system from 250 kW.

• Design engineers at the concept stage, while the scheme can still be changed.

• Finance people and owners who look at cost of ownership, not the purchase price.

• Sites with limited grid capacity or a trigeneration project.

• Theaters, hotels, shopping centers and buildings near housing, where silence and no vibration matter.

FAQ

When does an absorption chiller beat an electric chiller?

When the site has cheap or waste heat, a high tariff or a shortage of grid capacity, a trigeneration project, a 15–25 year savings horizon, or strict limits on noise and vibration. At 1,000 kW of cooling such a machine saves about RUB 1.02 million a year and lasts 5–10 years longer than an electric chiller.

Is an absorption chiller hard to operate?

The controls run the machine without a full-time operator, the controller interface is in Russian, and staff training takes 2–3 days. Crystallization and corrosion are risks of cheap machines: Thermax units have a tray-type anti-crystallization system and a corrosion inhibitor in the solution. Real sites run for 25–30 years without a major overhaul.

Where do absorption chillers already run?

At Apatit (PhosAgro group) in Cherepovets, two steam-fired machines (3,766 kW) work with NCT cooling towers: output grew by 12.5% and seasonal defects in fertilizer granulation were eliminated. At Polema in Tula, a 4.6 MW steam-fired Thermax machine runs and chromium output grew from 800 to 1,250 kg a day. At the Triumph Plaza shopping and entertainment complex, a 1,255 kW machine removed limits on noise and electrical capacity. Thermax has more than 5,500 installations worldwide; we have more than 50 absorption chiller projects in Russia and the CIS.

Related articles

• What is an absorption chiller? How it works, when it beats a chiller

• Trigeneration: power, heat and cooling from gas, and when it pays off

• Chiller total cost of ownership: purchase vs 15 years of running

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