A remote RTU or a cathodic-protection rectifier needs a steady trickle of DC power, and at a site with no grid and unreliable winter sun, solar alone may not deliver it. A gas-fired thermoelectric generator answers that need by turning the heat of a small burner directly into electricity through solid-state modules, with no engine, no alternator, and no moving parts to wear out. As long as there is fuel gas, it produces power day and night, in any weather. This guide explains how a gas-fired TEG generates DC power, the wattage tiers and fuel-gas draw involved, and where it is the better remote-power choice than solar in low-sun latitudes.
Thermoelectric Generator in one line: A thermoelectric generator, or TEG, is a solid-state device that converts heat directly into DC electricity using thermoelectric modules, and the gas-fired type used for remote power heats those modules with a small fuel-gas burner while the other side is kept cool, so the temperature difference across them produces power. It has no moving parts, runs continuously day and night regardless of weather as long as fuel gas is supplied, and is used to power remote RTUs, telemetry, and cathodic-protection systems. Its main trade-offs are a low conversion efficiency that means a continuous fuel-gas burn and a modest, fixed power output measured in watts.
A gas-fired TEG is built around thermoelectric modules, semiconductor devices that generate a voltage when one side is hotter than the other. In the generator, a small enclosed burner heats one face of the modules while the opposite face is held cool by a heat sink or fins exposed to ambient air. The temperature difference across the modules drives a DC current, and combining many modules produces a usable DC output at the voltage the load needs, typically the same low-voltage DC that powers RTUs and telemetry. The hotter the burner side and the cooler the sink side, the more power the modules make.
The defining characteristic of this arrangement is that it is entirely solid-state. There is no piston, no shaft, no bearing, and no alternator; the only consumable is the fuel gas and the pilot arrangement that keeps the burner lit. That absence of moving parts is the TEG's headline advantage for remote duty, because it means there is very little to break, minimal maintenance, and a long service life at a site that may only be visited a few times a year. A machine with no rotating parts does not need oil changes or bearing replacements and does not vibrate itself apart.
It should be clear that this heat-to-electricity conversion is a power-generation function, not a sensing one. The same underlying thermoelectric effect that makes the modules produce power is used at tiny scale in temperature sensors, but a TEG is a purpose-built generator sized to run a real electrical load continuously, with a burner deliberately heating a stack of modules to make watts. Its job is to keep an RTU, a radio, or a cathodic-protection rectifier energised around the clock, and it is sized and rated as a power source, in watts of continuous output.
Gas-fired TEGs are made in a range of power tiers, from small units putting out a handful of watts to larger units producing on the order of tens or a few hundred watts of continuous DC, and a model is chosen to match the site's steady load plus a margin. Because the output is essentially fixed by the burner and module stack, a TEG is a constant-power source rather than one that ramps with demand, so it is normally paired with a battery bank that buffers short load peaks and carries the site through any brief interruption. The designer sizes the TEG to the average continuous draw and lets the battery handle the transients.
The cost of that steady output is a continuous fuel-gas burn, because thermoelectric conversion is inefficient - only a small fraction of the heat released by the burner becomes electricity, and the rest is rejected as waste heat. That means a TEG consumes fuel gas every hour of every day whether or not the full output is being used, so its running cost is a real and continuous draw on the site's gas. Where the gas is the operator's own low-value produced gas this is often acceptable, but the fuel draw is the number a designer weighs against alternatives, and it is why TEGs are sized carefully rather than simply oversized.
The applications that suit a TEG are the ones that need reliable, uninterrupted low-power DC at a site with fuel gas but no grid. Powering an RTU and its radio at a remote wellhead or pipeline valve, energising instrumentation, and driving impressed-current cathodic-protection systems on pipelines are the classic uses. What these share is a modest, constant load that must not go dark, at a location where running a power line is uneconomic and where a mechanical generator would demand too much maintenance. The TEG's continuous, maintenance-light output is a good fit for exactly that profile.
The most useful way to place a TEG is against solar-plus-battery, its main alternative for off-grid remote power. Solar is clean and has no fuel cost, but its output collapses in short winter days, at high latitudes, under persistent cloud, and when panels are snowed over, and it must be oversized with days of battery autonomy to ride through those spells. A TEG produces the same power at midnight in December as at noon in June, so in low-sun latitudes and in applications that cannot tolerate a dark, snowy week, it delivers a reliability that solar struggles to match without a very large and costly array and battery. Where sun is plentiful, solar's zero fuel cost usually wins; where sun is scarce and the load must never drop, the TEG's weatherproof steadiness wins.
Because a TEG is a critical single point of power for the site it feeds, it is worth monitoring, and a cloud SCADA platform such as Merobix can watch it through the same channels it watches everything else. The most telling value is the DC output voltage or the battery-bus voltage the TEG maintains, because a healthy TEG holds the bus up while a burner that has gone out or a module stack that is degrading lets the voltage sag as the battery takes over and slowly discharges. Fuel-gas supply pressure to the burner and, where instrumented, the burner or pilot status round out the picture of whether the generator is actually running.
The practical payoff of that monitoring is time to respond before the site goes dark. A TEG whose burner has extinguished will keep the RTU alive on battery for a while, and if the falling bus voltage is trended and alarmed through the cloud, staff learn about the outage during that battery window rather than discovering it when the site finally drops off comms entirely. For a cathodic-protection TEG the stakes are different but the logic is the same - a lapse in protection current needs to be known - and surfacing the TEG's output and fuel status remotely lets an operator distinguish a generator fault from an ordinary comms glitch and dispatch before the battery runs flat.
It heats one side of solid-state thermoelectric modules with a small fuel-gas burner while keeping the other side cool with a heat sink, and the temperature difference across the modules drives a DC current. Many modules combined produce a usable low-voltage DC output for the load. There are no moving parts involved, only the burner and the modules, so the generator runs continuously with very little to wear out.
A TEG is better where the sun is unreliable and the load cannot be allowed to go dark: high latitudes, short winter days, persistent cloud, or sites where panels get snowed over. Because it produces the same power around the clock in any weather, it avoids the large oversized array and multi-day battery bank that solar needs to survive a dark, snowy stretch. Where sunlight is plentiful, solar's zero fuel cost usually makes it the better pick, so the two are chosen based on the site's insolation and how critical continuous power is.
Thermoelectric conversion is inefficient, so only a small fraction of the heat the burner releases becomes electricity and the rest is rejected as waste heat. To maintain the temperature difference the modules need, the burner must run continuously whenever the generator is producing power, which means a constant fuel-gas draw day and night. That ongoing fuel consumption is the main running cost of a TEG and the figure designers weigh against solar and other options.
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