In this article, we will explore the 9 Best Green Energy Penny Stocks to Invest In.
The Iran conflict has caused shipping troubles in the Strait of Hormuz, disrupting the oil supply chain and leading to a sharp spike in energy prices around the world. In this light, global demand for renewable energy has accelerated as businesses and households seek alternatives.
From the war in Ukraine to the war in Iran, current geopolitical conflicts have exposed the vulnerability of the global oil supply chain. With this has come a shift in focus regarding the renewable energy transition. It is no longer just a matter of environmental benefits, but also a national security necessity.
Addressing government officials in Paris last month, the UN climate chief, Simon Stiell, spoke about the freedom that renewable energy offers.
“Those who’ve fought to keep the world hooked on fossil fuels are inadvertently supercharging the global renewables boom,” Stiell said, according to a Reuters report on April 30. “Renewables offer safer, cheaper, cleaner energy that can’t be held captive by narrow shipping straits, or global conflicts,” he added.
Countries are seeking energy independence, or at least diversifying energy systems, to protect against external shocks. Add to this the tightening emissions regulations and growing demand for AI data center power, and you can see why interest in renewables is soaring.
As the buildout of solar, wind, and other alternative energy sources continues, demand is surging for energy storage solutions. On May 7, Bloomberg reported that the annual addition of energy storage reached 112 gigawatts in 2025, increasing 48% from 2024 and setting another deployment record.
On May 6, the International Renewable Energy Agency released a report in which it said that wind and solar energy paired with battery storage can provide steady power more affordably than fossil fuels.
With that said, this article discusses the 9 best green energy penny stocks to invest in.
Our Methodology
To select our 9 best green energy penny stocks to invest in, we used the Finviz stock screener, sifted through various ETFs, and scanned financial media reports and industry publications to identify companies participating in the renewable energy space. We looked for companies with shares trading under $5. We ended up with dozens of stocks in our initial list and applied additional filters to pick out the best. We looked for stocks with at least 15% upside potential as of May 7. Additionally, we checked the stocks’ hedge fund popularity using the Insider Monkey database as of Q4 2025. Finally, we ranked the stocks in ascending order based on upside potential.
Why are we interested in the stocks that hedge funds pile into? The reason is simple: our research shows we can outperform the market by imitating the top stock picks of the best hedge funds. Our quarterly newsletter’s strategy selects 14 small-cap and large-cap stocks every quarter and has returned 498.7% since May 2014, beating its benchmark by 303 percentage points (see more details here).
Best Green Energy Penny Stocks to Invest In
9. Energy Vault Holdings Inc (NYSE:NRGV)
Stock Price: $4.21
Number of Hedge Fund Holders: 24
Upside Potential: 19.16%
Energy Vault Holdings Inc (NYSE:NRGV) is one of the best green energy penny stocks to invest in. Energy Vault shares have climbed almost 40% over the past month and soared more than 450% in the past 12 months.
Energy Vault reported its Q1 2026 results on May 5. Revenue rose 156% YoY to $21.9 million, adjusted gross profit rose 25% YoY to $6.1 million, and cash increased 148% to $117 million. Additionally, the company’s backlog more than doubled from the prior year to $1.35 billion.
The quarter revealed a major milestone in the transformation of Energy Vault’s business model, and the management spoke much about it.
Just a little over a year ago, 80% of the company’s backlog was tied to energy storage EPC projects, which have low profit margins. The Q1 2026 report shows that Energy Vault has shifted 80% of its backlog to the high-margin independent power producer (IPP) projects. The IPP projects not only have higher margins than EPC projects, but they also generate recurring revenue.
Looking ahead, Energy Vault anticipates its full-year 2026 revenue in the band of $225–$300 million. That indicates a growth of 30% YoY at the midpoint of the guidance. The company is targeting a cash position of $150 million to $200 million at the end of 2026.
Energy Vault Holdings Inc provides energy storage solutions to utilities and industrial customers. Its solutions support long-duration energy storage using battery systems and gravity-based technology. The company also operates as an independent power producer, helping to meet the power demand of AI data centers.
8. Opal Fuels Inc (NASDAQ:OPAL)
Stock Price: $2.25
Number of Hedge Fund Holders: 8
Upside Potential: 44.74%
Opal Fuels Inc (NASDAQ:OPAL) is one of the best green energy penny stocks to invest in. On April 21, Opal Fuels Inc announced the signing of an agreement to monetize tax credits under Section 45Z of the US tax code. Section 45Z was created to encourage production of low-carbon fuels, such as renewable natural gas, for the transportation market.
Opal Fuels said the agreement marks a milestone in advancing its strategy to optimize the value of its platform and expects the first closing in Q2 2026. The company highlighted its efforts to help fleets replace diesel with renewable fuels to enjoy cost savings and stable pricing.
Opal Fuels expects proceeds from monetizing Section 45Z to strengthen its liquidity and support future growth investments. The company looks to invest in new production projects and expand its fuel distribution infrastructure, saying this will help accelerate wider fleet adoption of renewable transportation fuel.
Section 45Z of the tax code, also known as the Clean Fuel Production Credit, has bipartisan support. According to Opal Fuels, the bipartisan support provides policy certainty and bolsters industry confidence in the program’s stability and longevity.
Opal Fuels Inc produces and distributes renewable natural gas (RNG). It operates RNG production facilities fed by organic waste from dairy farms and landfills. Opal Fuels distributes its gas through a nationwide network of fueling stations that serve transport fleets.
7. Montauk Renewables Inc (NASDAQ:MNTK)
Stock Price: $1.41
Number of Hedge Fund Holders: 10
Upside Potential: 47.26%
Montauk Renewables Inc (NASDAQ:MNTK) is one of the best green energy penny stocks to invest in. The stock has gained more than 20% in the past month, and Street predictions indicate it has more room to rise.
Montauk Renewables Inc reported its Q1 2026 results on May 6. The report showed revenue grew 9% YoY to $46.4 million. This topline growth was supported by biofuel credits called RINs. The company said its RINs sold during the quarter increased 25.5% YoY to 12.4 million.
The biogas fuels and electricity company said its renewable natural gas production was flat year-over-year at 1.4 million MMBtu. However, Montauk made a profit in the quarter, reporting a net income of $5 thousand, compared to a net loss of $0.5 million in the same period a year ago.
Looking ahead, Montauk expects to produce 5.8 million to 6 million MMBtu of renewable natural gas (RNG) in 2026. It anticipates RNG revenue between $175 million and $190 million for the year. In its renewable electricity generation (REG) business, the company expects to produce 195,000 to 207,000 in 2026. It projects REG revenue between $33 million and $37 million.
Pennsylvania-based Montauk Renewables Inc is in the business of producing fuels and electricity from biogas. It produces renewable natural gas and generates renewable electricity by capturing methane from landfills and agricultural waste.
6. ESS Tech Inc (NYSE:GWH)
Stock Price: $1.13
Number of Hedge Fund Holders: 8
Upside Potential: 119.30%
ESS Tech Inc (NYSE:GWH) is one of the best green energy penny stocks to invest in. According to Street forecasts, GWH stock could soar more than 100% from its current level.
ESS Tech Inc reported its Q1 2026 results on May 7. The report showed the company generated $128,000 in revenue, compared with $0.6 million in the same period the prior year. The management said the revenue decline was due to the company delivering fewer equipment to customers compared to the prior-year period.
However, ESS Tech’s net loss narrowed to $15.9 million from $18 million in the prior-year period. Moreover, the company’s financial position improved, with the management revealing $21.5 million in total liquidity.
Looking ahead, ESS Tech CEO Kate Suhadolnik said the focus remains on expense control and financial flexibility to support the company’s operational and commercial priorities. ESS Tech has secured a $9.9 million contract for a large energy storage system to support a US Air Force research lab operation.
As it seeks additional business opportunities, ESS Tech is expanding beyond its traditional long-duration energy storage market segment. On April 30, ESS Tech announced a strategic partnership with Alsym Energy to enable it to enter the short and medium-duration energy storage segment.
ESS Tech Inc provides energy storage solutions. Its technology supports energy security, reliability, and resilience. The company helps its customers get the most out of excess energy. ESS Tech was formed in 2011 and is based in Oregon.
5. Clean Energy Fuels Corp (NASDAQ:CLNE)
Stock Price: $2.24
Number of Hedge Fund Holders: 21
Upside Potential: 123.21%
Clean Energy Fuels Corp (NASDAQ:CLNE) is one of the best green energy penny stocks to invest in. On May 4, Clean Energy Fuels Corp announced the opening of additional renewable gas stations to expand its network of fueling locations. The company said it opened six new gas stations at strategic spots in California, New Jersey, Oklahoma, Michigan, and Washington. It said the new stations are near distribution centers and located along major freight corridors.
Clean Energy Fuels’ renewable natural gas (RNG) is sold as an alternative fuel for commercial vehicles. The spike in diesel prices as a result of the Middle East crisis has made RNG more attractive to fleet operators.
Clean Energy Fuels’ executive Chad Lindholm commented that with the high and volatile diesel prices, the timing was perfect to expand the company’s RNG offering. Lindholm noted that Clean Energy Fuels’ RNG offers price-stable and low-cost fuel to help fleets reduce their carbon emissions affordably.
The new gas stations strengthen Clean Energy Fuels’ network that spans more than 600 fueling locations across North America. The company’s stations serve refuse, trucking, municipality, and operations fleets.
Clean Energy Fuels Corp produces and sells renewable natural gas used to power commercial vehicles, including heavy-duty trucks and buses. Its RNG is methane-based and is derived from organic waste, including dairy farm wastes. Clean Energy Fuels sells its RNG through a network of fueling stations.
4. Fuel Tech Inc (NASDAQ:FTEK)
Stock Price: $1.39
Number of Hedge Fund Holders: 4
Upside Potential: 212.50%
Fuel Tech Inc (NASDAQ:FTEK) is one of the best green energy penny stocks to invest in. Fuel Tech Inc stock is up around 60% over the past 12 months. The Street expects it to explode more than 200% from its current level.
In its Q1 2026 report, released on May 5, Fuel Tech Inc said its consolidated revenue declined to $6.1 million from $6.4 million a year ago. That’s a drop of 5% YoY. Additionally, the company’s net loss increased to $1.4 million from $0.7 million a year ago.
Those were the results. But getting into the details, Fuel Tech’s high-margin air pollution control (APC) business continued to grow. The APC segment revenue increased 23% to $1.6 million, and segment gross margin expanded to 38.3%, compared with 32.6% a year ago.
Fuel Tech closed Q1 with a backlog of $6.9 million in its APC segment, and the backlog has expanded since. On April 28, the company announced winning multiple APC contracts worth $10 million. It secured these contracts with utility and industrial customers.
The largest of these contracts was secured from a Midwest municipal utility. It involves integrating Fuel Tech’s Selective Catalytic Reduction pollution control technology with the utility’s natural gas-fired turbines.
Fuel Tech Inc provides technologies for air pollution control, water treatment, and process optimization. Its solutions help support grid reliability and resilience. Moreover, the company offers systems that support the production of green hydrogen, a source of clean energy.
3. Ocean Power Technologies Inc (NYSEAMERICAN:OPTT)
Stock Price: $0.36
Number of Hedge Fund Holders: N/A
Upside Potential: 318.41%
Ocean Power Technologies Inc (NYSEAMERICAN:OPTT) is one of the best green energy penny stocks to invest in. The Street expects the stock to climb more than 300% from its current level.
Ocean Power Technologies Inc continues to see demand for its PowerBuoy platform as it also works to solve a major problem in its industry: offshore autonomy. On May 7, the company announced progress in its offshore charging and autonomous operations program.
It was able to successfully demonstrate a system that allows maritime drones to dock, recharge, and return to operations without manned support. With that, the system addressed a major limitation in offshore autonomy.
The company plans to integrate the autonomous docking and charging capability into its PowerBuoy platform. It said this would create offshore charging points capable of supporting extended, lower-cost operations at sea.
More customers are reaching Ocean Power Technologies for its PowerBuoy system, which provides power and communication solutions at sea. On April 13, Ocean Power Technologies announced the deployment of its first PowerBuoy system for the US Department of Homeland Security.
It deployed the system off the California coast to support maritime surveillance for the U.S. Coast Guard. Additional PowerBuoy systems are expected to be deployed under the DHS contract.
Ocean Power Technologies Inc is a New Jersey-based renewable energy company serving the maritime sector. It converts ocean waves, wind, and solar energy into electric power for offshore applications. Through its PowerBuoy platform, the company provides power and communication solutions for offshore operations.
2. Gevo Inc (NASDAQ:GEVO)
Stock Price: $2.03
Number of Hedge Fund Holders: 10
Upside Potential: 326.83%
Gevo Inc (NASDAQ:GEVO) is one of the best green energy penny stocks to invest in. GEVO stock is up almost 80% over the past year. The Street sees it exploding more than 300% from its current level.
In its Q1 2026 report, Gevo Inc said it generated $43 million in revenue, compared to $29 million a year ago. The company made a $22 million loss in the latest quarter, the same as a year ago. The management said the latest results included $11 million in losses tied to debt refinancing and simplification transactions.
Adjusted EBITDA came to $9 million. That compares with the negative adjusted EBITDA of $15 million in Q1 2025.
Looking ahead, Gevo targets around $30 million in adjusted EBITDA in 2026, up from $17 million in 2025. The company expects to get there through revenue growth, operational performance, and cost controls.
Gevo’s growth plans include the Alcohol-to-Jet project, also called the ATJ-30. This project is about converting alcohols, such as ethanol, into jet fuel. The company said it has received interest from various capital providers to finance the project. Its goal is to secure financing for the ATJ-30 project by the end of 2026.
Gevo Inc, based in Colorado, is a renewable chemicals and biofuels company. It is focused on producing sustainable, low-carbon fuels. These include renewable gasoline, renewable diesel, and sustainable aviation fuel.
1. Aemetis Inc (NASDAQ:AMTX)
Stock Price: $3.08
Number of Hedge Fund Holders: 8
Upside Potential: 656.17%
Aemetis Inc (NASDAQ:AMTX) is one of the best green energy penny stocks to invest in. Aemetis Inc stock has more than doubled year-to-date, and Street forecasts show it could soar over 650% from here.
The company reported its Q1 2026 results on May 7. The report showed revenue increased 27% YoY to $54.6 million. The company generated a gross profit of $2.8 million, compared to a loss of $5.1 million in the same quarter of the prior year. Aemetis closed the quarter with $4.8 million in cash.
The quarter was supported by growth in the renewable natural gas (RNG) and biodiesel segments. Aemetis said its biodiesel sales increased to $10.5 million as it resumed shipments under new tender orders.
The company recorded $4 million in revenue tied to the Section 45Z tax credit program. This tax credit program is designed to boost domestic production of low-carbon transportation fuels. Aemetis said $1.4 million of the Section 45Z tax credit was earned through its renewable natural gas segment, while $2.6 million was earned through the ethanol production segment.
Looking ahead, Aemetis said it is pursuing a broad financing plan to address both near-term needs and fund continued growth across its platforms. Among the growth efforts is the expansion of the renewable natural gas production capacity. The company is also working toward the IPO of its Indian subsidiary, which produces biofuels.
California-based Aemetis Inc produces renewable natural gas and biofuels. Its solutions help businesses lower energy costs and reduce emissions. It has a facility in California that converts dairy waste to renewable natural gas. It also produces ethanol at a California plant. In India, it has a biodiesel production facility, and the company is developing a sustainable aviation fuel plant in California.
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