For many years, Cambodia entrusted its future to the seabed of the Gulf of Thailand. Looking back on the history of post-independence economic development, oil and gas exploration has repeatedly been invoked as a hope that could fundamentally transform the structure of the national economy. At the end of 2020, Singapore-based KrisEnergy finally began production at the Apsara oil field, Cambodia’s first offshore oil project. Yet output fell far short of expectations, and in 2021 the company was forced into liquidation due to insolvency. In little more than half a year, the oil field effectively ceased operations, and Cambodia’s “first offshore oil field” was shut down before it could find a sustainable path forward. The fact that expectations for underground resources collapsed is a grave one. At the same time, however, this episode paradoxically revealed that the resource Cambodia should truly be focusing on is not beneath the sea, but spread across the land. Cashew orchards stretching from the northern highlands down into the central plains have, over the past decade or so, expanded to a genuinely national scale. According to statistics from the Cashew Nut Association of Cambodia and others, production in 2024 reached around 850,000 tonnes, making the country the world’s second-largest producer of raw cashew nuts. Around 90 percent of this is exported to Vietnam as in-shell raw material. Hidden within that single word “in-shell” is the potential for a very different kind of oil field. The shell of the cashew nut contains an oil known as cashew nut shell liquid, or CNSL. This is a special type of oil whose main constituents are phenolic compounds such as anacardic acid and cardanol. It has long been used, through processes such as thermal cracking and distillation, as a feedstock for biodiesel fuels and industrial products including epoxy resins. Studies from various countries report that the shell fraction contains roughly 20 to 30 percent CNSL, and that processing 100 kilograms of raw nuts yields around 70 to 75 kilograms of shell. What happens if we combine these data points and make a conservative estimate? If we assume that 30 percent of Cambodia’s 850,000 tonnes of raw nuts is shell, and that 20 to 25 percent of that shell can be recovered as CNSL, then in theory the country could obtain in the order of 40,000 to 70,000 tonnes of CNSL per year. Even under cautious assumptions that factor in extraction efficiency and variations in quality control, this still represents a fuel potential of tens of thousands of kiloliters in diesel-equivalent terms. This is not a trivial by-product. In macroeconomic terms, it is a volume that fully deserves to be treated as an energy resource. The reasons why CNSL is attracting attention are not limited to its quantity. First, it is a biofuel derived from a “non-edible residue.” First-generation biofuels that use food crops as feedstock — corn, sugarcane, palm oil and the like — are increasingly subject to regulatory tightening worldwide because of food-fuel competition and land-use change. CNSL, by contrast, is extracted from shells that would otherwise be discarded. It does not directly conflict with food security or land use. Second, there is its performance as a fuel. CNSL and CNSL-based biodiesel have high calorific values, and experimental studies have shown that diesel engines can operate with blends of 20 to 30 percent, and in some cases even up to 50 percent. Third, there is the energy characteristic of the shell itself. Once CNSL has been extracted, the deoiled shell can be processed into briquettes and other forms of solid fuel with a calorific value of roughly 18 to 23 MJ per kilogram. Research in several countries suggests that this makes it comparable to low-grade coal as an energy source. If we include shell oil, deoiled shell and even cashew trees that are periodically cut when orchards are renewed, cashew can be positioned as a “multi-layered biofuel resource” capable of supplying liquid and solid fuels. The significance of this resource becomes even clearer when viewed in the light of Cambodia’s energy policy. The government’s Power Development Master Plan 2022–2040 is a long-term blueprint that seeks to pursue power-sector decarbonization and energy security simultaneously. It sets out a goal of achieving net-zero emissions by 2050 and supplying around 70 percent of the country’s electricity from renewable sources by 2030. In practice, the share of hydro and solar generation is rising, and electrification rates are improving. Yet outside of the power sector — in areas such as boilers for drying agricultural produce, heat for food processing, self-generation in small and medium-sized factories, and fuels for farm machinery and trucks — energy consumption remains heavily dependent on imported diesel and heavy fuel oil. The PDP lays out a clear pathway for raising the renewable share in the power sector, but for this kind of dispersed fuel demand, it has yet to present a concrete solution. This is precisely where CNSL and cashew shell fuels can play a role. If this resource could be extracted and used within Cambodia, a different kind of “energy revolution” could take place in rural areas. Imagine, for example, a medium-sized cashew processing plant located near the production areas. A factory handling 10 tonnes of raw nuts per day would generate shell waste on the order of several tonnes, and the CNSL that could be extracted from that volume would amount to several hundred liters per day. If CNSL were used as boiler fuel or co-fired in small diesel generators, the plant could cover part of its own heat and power demand, while also using surplus output to supply electricity to nearby villages through a micro-grid, and to fuel trucks and agricultural tractors. Even when one makes conservative assumptions about energy efficiency and capital cost, it is far from unrealistic to envision such a setup circulating several megawatt-hours of electricity and several thousand kilowatt-hours of thermal energy per day in a single area. This is not a centralized power system relying on large-scale plants. It is a distributed energy system in which “farm, factory, village and transport” form a single integrated loop. In 2025, as border tensions with Thailand intensified, the Cambodian government made the decision to suspend all imports of fuel and gas from Thailand. Armed clashes and civilian evacuations occurred along the frontier, and Thailand responded by closing multiple border checkpoints. Thanks to diversification of import sources and fuel stockpiles, domestic supply instability did not fully surface. Even so, it is impossible to deny that society was confronted with the stark reality that fuel flows can be halted by a single bout of political tension. An energy system dependent on external supply is acutely vulnerable to geopolitical shocks. The lesson of that crisis is that securing renewable fuel within the country is not merely an environmental policy issue. It is a matter at the very heart of national security. At the same time, the Cambodian government has embarked on an important policy shift in the agricultural sector. The National Cashew Policy 2022–2027, adopted by the Cabinet in January 2023, is a medium to long-term strategy for the cashew industry. In addition to raising productivity and improving quality, it sets clear targets: increasing the domestic processing ratio to 25 percent by 2027 and to at least 50 percent by 2032. The aim is to move away from the current structure, under which almost all raw material is exported in-shell, and to restore processing capacity, employment and value added to the domestic economy. Yet the focus of that discussion remains firmly on processing and exporting edible kernels. The energy use of shell oil and deoiled shells, and the potential for a chemical industry based on CNSL, are not yet fully articulated within the policy documents. In other words, Cambodia is already a “cashew power” but has not yet become a “cashew shell oil power.” So long as the present structure of exporting in-shell nuts to neighboring countries continues, CNSL — a strategic resource with both energy and chemical value — will be turned into added value across the border. Raising the domestic processing ratio should not mean simply increasing the number of factories that roast and package kernels. Ideally, it should involve designing rural clusters that combine shell oil extraction facilities, lines for producing briquetted deoiled shells, and small-scale cogeneration systems. Only then will a genuinely Cambodian version of a “renewable fuel oil field” begin to take shape. Seen from this perspective, cashew nuts are no longer just an export crop. They emerge as a “platform crop” that links energy security, climate action and rural industrial development. For a country long regarded as lacking in underground resources, this represents the discovery of a strength hidden on the reverse side of that perceived weakness. Not having fossil fuel reserves means that in a decarbonizing world, Cambodia does not carry the burden of stranded assets. It also means that the country has more room to redesign its energy system from the outset around renewable sources and biomass resources. The age of underground resources is ending, and the age of above-ground resources is beginning. Cambodia’s oil field is no longer on the seabed. It lies in the highlands of Preah Vihear, in the fields of Kampong Thom, and in the hands of farmers across the country. A single drop of oil contained in a cashew shell is not just a fuel. It is a catalyst that reconnects agriculture and industry, countryside and state, environment and security. It symbolizes the very direction of the future that this country can choose. Cambodia can become an oil field of renewable fuel. The form of the next civilization, built not on fossil fuels but on the relationship between people and the land, has already begun to emerge on Cambodian soil.