Natural Gas Generators: Complete Buyer’s Guide 2026

Power Generation Enterprises•February 16, 2026• 11 min read

11 min read

Natural gas generators eliminate on-site fuel storage, produce 25–40% fewer emissions than diesel, and cost 30–50% less per operating hour for facilities with pipeline gas access. Power Generation Enterprises stocks Caterpillar G3512, G3516, CG137, and Waukesha VHP natural gas generators from 150kW to 2,000kW — all inspected and load-tested at our Santa Clarita, California facility.

Caterpillar G3516LE 850kW natural gas generator set - Power Generation Enterprises inventory — GS2749a Caterpillar G3516LE GeneratorSets 6

Natural gas generators produce electricity by burning pipeline natural gas or LNG instead of diesel, eliminating on-site fuel storage, reducing NOx emissions by 25–40% versus diesel equivalents (per EPA stationary source emissions data), and cutting fuel costs by 30–50% for facilities with utility gas access. This guide covers every major natural gas generator platform available today — from 75kW Caterpillar G3306 units to 2,000kW Waukesha industrial sets — including specifications, pricing, ideal applications, and what to look for when buying used.

Natural gas generators have taken significant market share from diesel in data centers, hospitals, wastewater treatment facilities, and co-generation plants over the past decade. Understanding when natural gas is the right choice — and when it isn’t — starts with the fuel supply, the application, and the regulatory environment.

Natural Gas vs. Diesel: When Each Wins

Natural gas generators are the correct choice when three conditions align: reliable pipeline gas access at adequate pressure (typically 5–7 psi minimum for generator supply), a facility that runs the generator frequently (prime power, co-gen, or regular exercising), and an application where diesel fuel storage creates logistical, environmental, or permitting complications.

Diesel holds the advantage in applications requiring absolute fuel security independent of utility infrastructure — military installations, remote sites without gas service, and locations where pipeline reliability is uncertain. A diesel generator with a 2,000-gallon sub-base tank operates completely independently of any utility. A natural gas generator tied to a utility gas main shares a single point of failure with the grid event that may have triggered the outage.

For most urban commercial and industrial facilities with reliable gas utility service, natural gas wins on operating cost, emissions compliance, and fuel management simplicity. For remote or mission-critical standby applications, diesel remains the safer choice.

Caterpillar Natural Gas Generator Platform

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CAT Gas Generators

Caterpillar produces the most extensive natural gas generator lineup in the industrial market — spanning the G3306 (75kW) through the G3520 (2,000kW) on spark-ignited gas platforms, plus the newer CG137 and CG170 continuous gas engine series designed specifically for prime power and co-generation applications.

The G3512 is the workhorse of the Caterpillar natural gas line. At 550kW to 1,000kW depending on configuration, aspiration, and fuel quality, the G3512 appears in more data centers, hospitals, and industrial facilities than any other Caterpillar gas generator. Its lean-burn combustion technology — the Electronic Ignition System (EIS) and Electronic Modular Control Panel (EMCP) — delivers 36–38% electrical efficiency in prime power service, competitive with diesel equivalents consuming more expensive fuel.

The G3516 extends the platform to 800kW–1,000kW in standard configuration and up to 1,600kW in high-output versions. G3516 units are the most common large-format natural gas generator in data center backup power applications and wastewater treatment plants requiring continuous duty. View our Cat G3516 800kW inventory →

The CG137-12 represents Caterpillar’s current-generation continuous duty gas engine, producing 400kW at exceptional thermal efficiency. Its Miller Cycle combustion with cooled external EGR meets Tier 4 emissions levels on natural gas without aftertreatment complexity. View our CG137-12 400kW inventory →

Waukesha Natural Gas Generators

Waukesha (now INNIO Waukesha) produces natural gas generators that dominate the 500kW–5,000kW prime power market in North America — particularly in oil and gas, co-generation, and continuous duty industrial applications. The VHP (Very High Performance) series is the Waukesha flagship: the VHP7042GSI produces 1,100kW on natural gas with exceptional thermal efficiency at continuous duty load factors that would stress competing platforms.

Waukesha’s key differentiation from Caterpillar is fuel flexibility. Waukesha gas engines operate on pipeline natural gas, wellhead gas with variable BTU content, landfill gas, digester gas, and propane without engine replacement — only fuel system recalibration. For oil and gas production facilities running on associated gas, Waukesha VHP units are the dominant technology because no other platform handles the variable composition of wellhead gas with the same reliability.

The trade-off: Waukesha engines have a smaller parts and service network than Caterpillar or Cummins. Outside of the oil patch and industrial co-gen market, finding qualified Waukesha service technicians requires planning. For facilities with dedicated maintenance staff, this is manageable. For facilities relying on third-party service, Caterpillar’s dealer network depth is a meaningful advantage. View our Waukesha VHP7042GSI 1100kW →

Cummins and Jenbacher Natural Gas Options

Cummins GTA855 and QSV91G natural gas generators serve the 180kW–2,000kW market with the same parts availability advantage that makes Cummins diesel generators dominant in the used market. The GTA855 is particularly common in the 150–200kW range — a cost-effective natural gas option for smaller commercial facilities and agricultural applications.

Jenbacher (GE Vernova) gas engines represent the premium European alternative — exceptional efficiency at 42–45% electrical efficiency on pipeline gas, but engineered specifically for prime power and co-generation applications rather than standby service. Jenbacher units appear primarily in wastewater treatment, landfill gas, and industrial process heat-and-power applications. They are rarely the correct choice for emergency standby.

Buying a Used Natural Gas Generator

Used natural gas generators require additional due diligence beyond what diesel units demand. Gas engine condition is strongly influenced by fuel quality history — an engine that has run on clean pipeline gas its entire life is a fundamentally different purchase than one that ran on landfill gas or variable-quality wellhead gas. Always request fuel type history before inspection.

Valve and seat condition is the primary mechanical concern on gas engines. Natural gas combustion is hotter than diesel combustion, and exhaust valve seat recession occurs at predictable intervals on most platforms. Ask for valve inspection records. On Caterpillar G3512 and G3516 units, valve work at 8,000–12,000-hour intervals is expected maintenance — not a red flag — but ensure it has been completed at the correct intervals.

Ignition system condition matters more on gas units than any diesel equivalent. The Electronic Ignition System (EIS) on Caterpillar gas generators and equivalent systems on Waukesha and Cummins control combustion timing, knock detection, and air-fuel ratio. Inspect spark plug condition and ignition module logs before purchase. A history of knock events indicates either fuel quality issues, timing problems, or detonation damage that may not be visible externally.

Power Generation Enterprises inspects all natural gas generators at our Santa Clarita facility before offering them for sale. Each unit undergoes engine oil analysis, compression testing, ignition system inspection, and a documented load test. Call +1 (818) 484-8550 for current natural gas inventory availability.

Dual-Fuel Generators: Natural Gas and Diesel Combined

Dual-fuel generators operate primarily on natural gas while maintaining the ability to switch to diesel — either automatically during gas supply interruptions or manually for extended outages. They eliminate the gas-supply dependency that makes pure natural gas unsuitable for mission-critical standby applications in earthquake zones, severe weather regions, or locations with older gas distribution infrastructure.

Most dual-fuel systems are diesel-primary with gas supplementation: the engine starts on diesel and gradually substitutes natural gas to reduce diesel consumption at load. True bi-fuel systems capable of running on 100% of either fuel independently are available but more mechanically complex and expensive. For facilities that need gas economics during normal operation and diesel security during extended emergencies — hospitals, data centers, and critical municipal facilities — dual-fuel is the correct architecture.

Key dual-fuel applications: hospitals in earthquake zones requiring full fuel independence; data centers with 72-hour autonomy mandates who want gas economics during monthly test runs; municipal wastewater facilities running biogas co-generation with diesel backup. Power Generation Enterprises can source dual-fuel conversion kits for major platforms and has dual-fuel units in inventory periodically — call +1 (818) 484-8550 for current availability.

Natural Gas Generator Pricing

Used natural gas generators sell at a significant premium over equivalent diesel units in the 200kW–1,000kW range because of lower supply — fewer natural gas units are produced and fewer reach the used market annually. The table below reflects current market pricing for inspected units in serviceable condition. Pricing varies with hours, configuration, enclosure type, and regional market conditions.

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The pricing table above reflects typical market values for units in serviceable condition with verified operational history. Pricing premiums apply to units with recent major overhauls, complete enclosures, low hours, or documented load bank test records. Pricing discounts apply to units requiring service, with high hours, or sold without enclosures. Power Generation Enterprises provides detailed inspection reports on all inventory — call +1 (818) 484-8550 for specifics on any unit.

Waukesha VHP natural gas generator set at Power Generation Enterprises Santa Clarita — GS2762a Waukesha GeneratorSet 6

Model	Output	Application	Fuel Type	Used Price Range
Caterpillar G3306TA	135–150 kW	Light commercial standby	Pipeline NG / Propane	$15,000–$35,000
Caterpillar G3406TA	170–250 kW	Commercial standby / prime	Pipeline NG	$18,000–$45,000
Caterpillar G3512	550–1,000 kW	Data center / hospital / industrial	Pipeline NG	$65,000–$185,000
Caterpillar G3516 / G3516LE	800–1,600 kW	Large industrial / prime power	Pipeline NG	$95,000–$275,000
Caterpillar CG137-12	400 kW	Prime power / co-gen	Pipeline NG	$85,000–$145,000
Cummins GTA855	180 kW	Commercial / agricultural	Pipeline NG / Propane	$12,000–$28,000
Waukesha VHP7042GSI	1,100 kW	Oil & gas / co-gen / prime	NG / Wellhead / Landfill gas	$95,000–$225,000
Caterpillar G3532	2,000 kW	Utility / large industrial	Pipeline NG	$185,000–$350,000

DEF Requirements for Natural Gas Generators

Lean-burn Caterpillar natural gas generators — including the G3512 and G3516 — meet EPA emissions standards through combustion control rather than exhaust aftertreatment, so they do not require Diesel Exhaust Fluid (DEF). However, newer CG137 and CG170 series units with cooled EGR do use DEF in some configurations, as do any dual-fuel natural gas/diesel units in diesel mode.

For facilities operating mixed fleets of natural gas and Tier 4 Final diesel generators, maintaining DEF quality across multiple generator types is a common maintenance challenge. DEF crystallization in stationary generator tanks — which can sit partially filled for months between test runs — is the leading cause of SCR fault codes. The DEF Academy’s SCR maintenance guide covers prevention protocols specifically for generator applications, including pre-storage treatment that protects DEF systems through extended standby periods.

Pro Tips for Natural Gas Generator Buyers

Verify Pipeline Pressure Before Specifying

Most natural gas generators require 5–7 psi minimum supply pressure at the generator inlet. Industrial units above 500kW often require 10–15 psi. Call your gas utility before purchasing — low-pressure distribution systems common in older neighborhoods may not support large generators without pressure boosting equipment.

Request Valve Inspection Records on Used Units

Natural gas combustion runs hotter than diesel. Exhaust valve seat recession on G3512 and G3516 engines occurs at 8,000–12,000-hour intervals. This is normal maintenance — but confirm it has been done. An overdue valve inspection on a 15,000-hour unit is a significant expense that should be reflected in the purchase price.

Lean-Burn vs. Rich-Burn: Know Which You Have

Caterpillar G3512 and G3516 units are lean-burn engines with internal combustion control that meets Tier 4 emissions without aftertreatment on natural gas. Older rich-burn units require a three-way catalyst for California AQMD compliance. Confirm the combustion type for your regulatory environment before purchasing for California applications.

Co-Generation Is a 3–5 Year Payback for the Right Facility

Natural gas generators reject 60–65% of fuel energy as heat. For facilities with steady thermal loads — hospitals, food processing, large office buildings — capturing that heat for space conditioning or process heat via a co-generation system typically achieves full ROI in 3–5 years on a $200,000–$400,000 generator investment.

Dual-Fuel Retrofits Add Fuel Security Without Diesel Drawbacks

Dual-fuel systems allow natural gas generators to start on diesel and switch to gas, or operate on diesel if gas is interrupted. For facilities where fuel security is paramount but gas economics are preferred, dual-fuel configurations on Caterpillar and Cummins platforms offer the best of both. Expect $15,000–$40,000 for a factory-certified dual-fuel conversion.

Frequently Asked Questions

What is a natural gas generator?+

A natural gas generator is an internal combustion generator set that burns pipeline natural gas, LNG, or propane instead of diesel fuel to produce electricity. Natural gas generators use spark-ignited combustion rather than diesel compression ignition. They connect directly to utility gas supply lines, eliminating fuel storage requirements. Commercial and industrial natural gas generators range from 75kW (Caterpillar G3306) to over 10,000kW (GE Vernova Jenbacher J920). Power Generation Enterprises stocks used natural gas generators from 150kW to 2,000kW at our Santa Clarita, California facility.

How much does a natural gas generator cost?+

Used natural gas generators range from $15,000 for a small 135kW Caterpillar G3306TA to over $350,000 for a 2,000kW G3532 in excellent condition. Mid-range industrial units — the most commonly purchased segment — price as follows: Caterpillar G3512 (550–650kW) typically $65,000–$125,000; Caterpillar G3516 (800–1,000kW) typically $95,000–$185,000; Waukesha VHP7042GSI (1,100kW) typically $95,000–$225,000. New natural gas generators from major OEMs are 30–50% more expensive than equivalent used units. Call Power Generation Enterprises at +1 (818) 484-8550 for current inventory and pricing.

How does a natural gas generator compare to diesel?+

Natural gas generators cost 30–50% less per hour to operate than diesel equivalents in markets with utility gas access, because natural gas sells at roughly $4–$8 per MMBtu versus diesel at $18–$24 per MMBtu equivalent energy. Natural gas generators produce 25–40% less NOx than diesel and eliminate particulate matter almost entirely, simplifying AQMD and EPA permitting in California and other regulated markets. The trade-off: natural gas generators require pipeline gas connection, cannot be refueled during extended outages without stored LNG, and typically have shorter service intervals than diesel due to hotter combustion temperatures.

What size natural gas generator do I need?+

Size a natural gas generator at 1.25x your facility’s peak demand to allow for motor starting loads and derating for altitude or temperature. Common industrial sizes: hospitals and data centers typically require 500kW–2,000kW; commercial buildings 100kW–500kW; light industrial facilities 75kW–500kW. Natural gas generators derate more significantly than diesel at altitude — a G3512 rated at 1,000kW at sea level produces approximately 850kW at 5,000 feet elevation. Confirm your site conditions with a generator specialist before purchasing. Call Power Generation Enterprises at +1 (818) 484-8550.

Can a natural gas generator run during a power outage?+

Yes, with one critical condition: the facility must have underground gas utility service that remains pressurized during the power outage. Overhead gas distribution can be disrupted by the same events that cause power outages. Most urban commercial facilities have underground gas service and can rely on natural gas generators for extended outage coverage. For facilities in areas prone to simultaneous gas and power disruption — earthquake zones, severe weather regions, or remote locations — diesel or dual-fuel generators provide more reliable outage protection than pure natural gas systems.

Does Power Generation Enterprises sell natural gas generators?+

Yes. Power Generation Enterprises maintains active natural gas generator inventory at our Santa Clarita, California facility — including Caterpillar G3512, G3516, and CG137 series, Waukesha VHP units, and Cummins gas generators from 150kW to 2,000kW. All units are inspected, load-tested, and available for immediate delivery nationwide. Browse our natural gas generator inventory or call +1 (818) 484-8550.

Browse Natural Gas Generator Inventory

Power Generation Enterprises stocks one of the largest natural gas generator inventories in the western United States — Caterpillar G3512, G3516, CG137, Waukesha VHP, and Cummins gas units from 150kW to 2,000kW, all inspected and load-tested at our Santa Clarita facility. Request a quote or call to check current availability.

+1 (818) 484-8550

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Written by Power Generation Enterprises

Generator Specialist

Power Generation Enterprises buys and sells natural gas generators from our Santa Clarita, California facility. We maintain one of the largest natural gas generator inventories in the western United States, spanning Caterpillar G-series, Waukesha VHP, and Cummins gas platforms from 150kW to 2,000kW.