Algae biofuel was once promoted as one of the most promising green fuels, yet today it remains an experimental technology. Despite more than a decade of heavy investment from oil companies and venture capital, no algae fuel is sold at commercial scale. ExxonMobil’s high-profile programme ended in 2023, and the best-known start-ups either failed or moved away from fuel to sell food, feed and nutrition products.
The science is promising on paper, but the economics have not worked. This guide explains how algae become fuel, why the costs remain high, what happened to the big projects, and what the latest research says about the future.
How algae become fuel
To understand why the journey from pond to pump has been so difficult, it helps to look at the two main routes for turning microalgae into liquid fuel. The first is lipid extraction. Algae are grown, harvested and dewatered, the oils (lipids) are extracted, and the oil is converted into biodiesel by transesterification or into renewable diesel by hydrotreating.
The second route is hydrothermal liquefaction (HTL). Instead of drying the algae and extracting the oil, HTL cooks the whole wet algae slurry under heat and pressure. In a 2014 US national laboratory design case, algae slurry of about 20% solids was treated in subcritical water at roughly 2,000–3,000 psia and 300–350 °C. This produces a “biocrude” that is then upgraded in a refinery-style hydrotreater at roughly 350–400 °C.
HTL is particularly suited to wet feedstocks such as algae because it avoids the costly step of drying the biomass and extracting the oil. The process also produces watery and solid by-products from which nutrients and energy can be recovered, and in the design case nutrients and water are recycled back to the growing ponds. However, as of 2014, algae HTL and upgrading had only been demonstrated in the laboratory and at small engineering development scale.
Cultivation comes in two main forms. Open raceway ponds are cheaper but prone to contamination and the effects of weather. Closed photobioreactors offer more control but cost more. Seaweed (macroalgae) is a separate route: it is usually fermented to ethanol or digested to biogas, much like other biomass energy feedstocks, rather than pressed for oil. Concawe puts the averaged minimum selling price for seaweed ethanol at €1.4 per litre (2025), but calls the estimate uncertain because so little research exists.
How much it costs to produce algae biofuel
There is no commercial-scale market for algae fuel, so there is no market price. All the figures below are modelled estimates for hypothetical mature plants.
A 2025 review by Concawe, the European refiners’ research body, harmonised the assumptions across published techno-economic models. It found an averaged minimum fuel selling price of €2.2 per litre for lipid-extraction routes and €3.4 per litre for HTL. These prices assume a future algae productivity of 25 grams per square metre per day (g/m²/day), a US National Renewable Energy Laboratory target. The best state-of-the-art productivity is 18.6 g/m²/day, so real costs today would be higher.
The US Department of Energy (DOE) has also modelled costs. A 2014 design case estimated that a mature algae HTL plant could sell diesel at a minimum of $4.77 per gallon in 2011 dollars ($4.49 per gallon of gasoline equivalent, or gge). More recent DOE figures (2021–22 data, presented in April 2023) showed that algae grown on wastewater could bring modelled HTL fuel down to $2.61 per gge, in 2016 dollars. That figure relies on selling a fertiliser co-product. Producing sustainable aviation fuel (SAF) from algae by HTL was modelled at $5.42 per gge.
For context, the average US retail diesel price was $3.66 per gallon in 2025, according to the US Energy Information Administration, and that includes federal and state taxes. The units, currencies and years do not line up neatly, so a precise comparison is not possible. Even so, modelled algae costs, which already rest on optimistic assumptions, are well above typical fossil diesel production costs.
Real-world examples: hype and retreat
The history of algae fuel is one of large investments followed by retreats. The most prominent example is the partnership between ExxonMobil and Synthetic Genomics, the company founded by J. Craig Venter and later renamed Viridos.
The partnership began in 2009 and was reported to be worth US$600 million at the time. In 2017 the partners announced a genetically modified algae strain that, they said, more than doubled oil content without significantly slowing growth. In March 2018 ExxonMobil said it anticipated that 10,000 barrels of algae biofuel per day could be produced by 2025. That did not happen. In November 2021 the two companies signed a new joint development agreement, but in February 2023 Bloomberg reported that ExxonMobil had ended the relationship. Exxon’s Vijay Swarup was quoted as saying the company had other programmes ready for deployment and that “algae still needs some more work”.
After Exxon left, Viridos raised a $25 million Series A round in 2023, led by Breakthrough Energy Ventures with Chevron and United Airlines Ventures.
Sapphire Energy, founded in San Diego in 2007, raised more than $100 million in Series B funding in 2008 and $144 million in 2012, and received a $54.5 million US Department of Agriculture loan guarantee and a $50 million DOE grant. It began building a “Green Crude Farm” near Columbus, New Mexico, in 2011, expected to produce 100 barrels a day at full capacity. In 2019 the site was sold to Green Stream Farms, which uses it to grow algae for nutritional products and livestock feed; local press reported that the refinery operations appeared to have been discontinued.
Solazyme started out in fuels and industrial oils. In 2016 it decided to focus on food, feed and personal care, and renamed itself TerraVia. TerraVia filed for Chapter 11 bankruptcy in August 2017 after almost 15 years without making a profit, and the Dutch ingredients firm Corbion bought substantially all of its assets. Industry commentators linked the move away from fuel to the oil price collapse of 2014–15, which removed much of the price pressure behind early investment.
Advantages and limitations
Algae fuel has real advantages, which is why research continues. Algae can grow on non-farm land in saline water or wastewater, so they need not compete with food crops. They can capture CO2 from industrial flue gas. And the oil can be made into “drop-in” diesel or jet fuel that works in existing engines.
Lifecycle emissions can look good in specific scenarios. The DOE’s wastewater-algae HTL case modelled a 73% cut in greenhouse gas emissions compared with petroleum diesel. This is a modelled result, not a measurement from a working plant.
The main limitation is cost, driven by cultivation and harvesting. Algae grow as a very dilute culture, so separating them from huge volumes of water takes a lot of energy; Concawe names this upstream stage as the main bottleneck. High-value co-products such as omega-3s and protein could improve the economics, but Concawe warns those markets may be too small to support large-scale fuel production. That pattern fits the case histories: Sapphire’s site and TerraVia both ended up in food, feed and nutrition rather than fuel.
Early estimates suggested algae could yield many times more oil per hectare than land crops; one widely copied mid-2000s table lists about 95,000 litres per hectare, against about 1,190 for rapeseed. These are old theoretical upper bounds that have not been achieved at scale. Concawe says productivity of 25–30 g/m²/day and lipid content of about 50% are needed, while the best current productivity is 18.6 g/m²/day. (Hemp faces a similar gap between headline claims and per-hectare reality; see how hemp compares as an energy source.)
Does algae biofuel produce CO2?
Yes. Burning algae biofuel releases CO2 like any other hydrocarbon fuel. The climate benefit rests on the algae having absorbed that CO2 while they grew. The net result depends heavily on the energy used for mixing, harvesting, dewatering and processing.
Concawe’s 2025 review says greenhouse gas savings are hard to achieve, mainly because of the high energy demand of cultivation and harvesting. The DOE’s 73% reduction is a best modelled case for algae grown on wastewater, not a measured result from commercial production.
The UK angle
In the UK, algae biofuel has remained a research topic rather than an industry. The Carbon Trust’s Algae Biofuels Challenge, launched in 2008 with £8 million over three years from the Department for Transport and the then Department of Energy and Climate Change, aimed for 70 billion litres of algae biofuel a year by 2030, roughly 6% of road transport diesel. Eleven institutions were chosen from more than 80 proposals, including Swansea University, Plymouth Marine Laboratory, the Scottish Association for Marine Science and Newcastle University. There is no sign that the 2030 aim is still being pursued.
Swansea University also led EnAlgae, a four-year European project with partners across north-west Europe set up to speed up algal bioenergy. Today Swansea’s Algal Research Group runs one of the largest UK greenhouse facilities for growing microalgae, but its stated focus is the circular economy, wastewater and CO2 recycling, novel foods, pharmaceuticals and biostimulants. Biofuel is not listed among its current priorities.
We found no commercial algae fuel production in the UK as of October 2026. UK renewable transport fuel statistics list mainly bioethanol, biodiesel and HVO from wastes and crops, and biomethane; algae does not feature.
The future of algae biofuel
As of 2025, Concawe classes algae-to-liquid fuels as experimental, held back by economic and technical barriers. US DOE research continues to model algae-to-SAF via HTL, with a modelled cost of $5.42 per gge, so jet fuel rather than road diesel is now the main research target.
Where algae businesses have survived, they mostly sell higher-value products such as nutrition, feed and ingredients. Algae remain scientifically interesting: they grow fast, need no farmland and can make drop-in fuels. But after more than a decade of large investments, no one has made algae fuel cheap enough to compete with fossil fuels or with biofuels made from waste oils. Other lesser-known routes to energy from organic material are covered in waste-to-energy technologies you haven’t heard of.
Frequently asked questions
How much does it cost to produce algae biofuel?
Only modelled costs exist. Concawe (2025) estimates an averaged €2.2–3.4 per litre, assuming productivity better than today’s best. US DOE models give $2.61–5.42 per gallon of gasoline equivalent (2016 dollars). There is no market price because there is no commercial-scale production.
How is algae turned into biofuel?
There are two main methods. The first harvests and dewaters the algae, extracts the oil and converts it to biodiesel or renewable diesel. The second, hydrothermal liquefaction, cooks the whole wet algae at about 300–350 °C under pressure to make a biocrude that is then refined into fuel.
Why did ExxonMobil give up on algae biofuel?
In February 2023 Bloomberg reported that ExxonMobil had ended its partnership with Viridos (formerly Synthetic Genomics). An Exxon executive said the company had other programmes ready for deployment and that algae still needed more work. Its 2018 aim of 10,000 barrels a day by 2025 was not met.
Is anyone producing algae biofuel in the UK?
We found no commercial algae fuel production in the UK as of October 2026. University research continues, but Swansea’s group, for example, now focuses on wastewater recycling, food and other products rather than fuel.
Does algae biofuel produce CO2 when burned?
Yes. Like all hydrocarbon fuels, burning algae fuel releases CO2. The net benefit depends on the CO2 the algae absorbed while growing, minus the energy used to grow, harvest and process them, which Concawe says makes greenhouse gas savings hard to achieve.
What are the advantages and disadvantages of algae as a biofuel?
Advantages include fast growth, the ability to use non-farm land, saline water or wastewater, and the option of drop-in diesel and jet fuel. Disadvantages include high modelled costs, energy-intensive harvesting, and the fact that no process has yet proved commercially viable against fossil fuels.