Montauk Renewables (MNTK Quick QuoteMNTK - Free Report) shares have climbed 44% over the past six months, raising questions about whether investors should buy the stock following such a strong run. The company is expanding its renewable-energy operations, while earnings and revenue estimates point to further improvement. However, rising project costs, debt and dependence on renewable-fuel credit prices remain concerns. With the stock already recording substantial gains, investors need to assess whether Montauk's growth plans can support further upside.

MNTK Outperforms Other Clean Energy Stocks

Montauk's six-month performance has been considerably stronger than that of other clean energy stocks. During the same period, FuelCell Energy (FCEL Quick QuoteFCEL - Free Report) gained just 3.6%, while Clean Energy Fuels (CLNE Quick QuoteCLNE - Free Report) declined 38.6%. The difference suggests that investors have been more willing to buy Montauk shares, even though past returns offer no assurance of future gains.

6-Month Price Performance

Image Source: Zacks Investment Research

These companies operate in different parts of the clean energy business. FuelCell Energy develops systems that generate electricity through fuel-cell technology, including solutions for data centers. Clean Energy Fuels supplies natural gas and renewable natural gas to vehicle fleets through its fueling network. Montauk focuses on collecting gas from landfills and other organic waste sources and converting it into renewable natural gas or electricity. The company also earns revenues from environmental credits associated with qualifying renewable-energy production.

MNTK's Earnings and Sales Estimates Point to Growth

Montauk's earnings outlook provides another reason to consider the stock. The Zacks Consensus Estimate for 2026 earnings stands at 12 cents per share, suggesting an increase of 1,100% from 1 cent earned in 2025. For 2027, the consensus estimate is pegged at 17 cents per share, indicating another 41.7% improvement.

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Revenue estimates also suggest continued expansion. The Zacks Consensus Estimate for 2026 sales is $213 million, indicating 20.8% growth from 2025. Sales are expected to rise another 7.7% to $229.3 million in 2027.

These estimates suggest that analysts expect Montauk's business to improve over the next two years. Unlike FuelCell Energy, which is expanding its fuel-cell manufacturing capacity to meet demand for large power projects, Montauk is focused on increasing renewable-fuel production and developing waste-to-energy facilities. Clean Energy Fuels, meanwhile, is expanding renewable natural gas production and fueling services. Montauk will need to manage its costs and execute its projects efficiently to achieve the expected earnings growth.

Turkey Project and GreenWave Could Support MNTK's Expansion

Montauk's Turkey, NC, project is an important part of its growth plans. The company began generating electricity for sale from the facility in July 2026. By the end of August, Montauk had signed long-term agreements with more than 80 farming locations, providing access to over 415,000 hog spaces targeted for the project's first phase.

The $200-million project uses waste from hog farms to produce electricity. As more farms are connected to the facility, electricity generation could increase. The project is also expected to produce renewable-energy credits, creating another source of revenues.

Montauk's GreenWave joint venture offers a separate opportunity. It connects renewable natural gas produced by third parties with transportation markets where federal renewable-fuel credits can be generated. GreenWave contributed approximately $3.8 million in investment income during the second quarter of 2026.

This arrangement allows Montauk to earn income from renewable gas produced outside its own facilities. While Clean Energy Fuels operates an extensive transportation-fueling network, Montauk uses GreenWave to gain access to transportation-related credit opportunities. FuelCell Energy, in comparison, is pursuing opportunities in electricity generation through its fuel-cell systems.

Image Source: Montauk Renewables, Inc.

Montauk has also benefited from operating improvements at its McCarty and Apex facilities, which supported higher renewable natural gas production.

What Could Hold Back MNTK's Growth?

Despite these opportunities, Montauk faces risks that investors should consider. Its profitability depends heavily on environmental credit prices, particularly Renewable Identification Numbers, or RINs. A decline in credit prices could hurt revenues and earnings even if production remains stable. Changes in government regulations could also affect the value of these credits.

Project development carries additional risks. Construction delays, higher expenses and variations in available waste supplies could affect production plans. Montauk had $155 million outstanding under its senior credit facility as of June 30, 2026. Continued spending on major projects could put further pressure on its finances.

Should Investors Buy MNTK Stock Now?

Montauk's six-month rally may make some investors cautious, but its growth plans and improving earnings expectations still support a positive outlook. The Turkey project, GreenWave's contribution and improvements at existing facilities could help the company increase revenues and profitability. Although environmental credit prices, project expenses and debt remain risks, the expected earnings and sales growth suggests that the stock could have further upside. MNTK currently carries a Zacks Rank #1 (Strong Buy), making it an attractive investment consideration even after its recent gains.

You can see the complete list of today’s Zacks #1 Rank stocks here.