植物油作為燃料

植物油包括純植物油 (PPO)和廢植物油 (WPO)，可用作（生物）燃料。PPO是新的植物油，而WPO是已經用於油炸食品的純植物油。植物油是一種非常有用的燃料，因為它使用植物作為原料。植物能夠以相對較低的成本收集大量太陽能（由於它們出現的數量和它們可以佔據的空間量）。請注意，PPO 可以進一步分為第一代和第二代燃料類型。WPO始終是第二代燃料。

應用

植物油可用作加熱或烹飪燃料，並用於活塞式蒸汽機、內燃機（柴油）、斯特林發動機、蒸汽和燃料動力渦輪機。通過在發動機中使用它們，可以提供機械功（即用於運輸目的、穀物碾磨等）或發電（通過添加交流發電機或發電機；該設備稱為“發電機組”或發電機組，它們通常用於固定應用）。最後，植物油可用於發電機組，不僅可以發電，還可以供熱。通常，這些也是普通發電機組，產生的熱量只是發動機的廢熱，不管怎樣，由於發電機組的巧妙使用，效率提高了，這些發電機組就被稱為熱電聯產系統。

在內燃機中的應用

目前，很少有 IC 發動機標準配置為使用植物油運行，需要對發動機進行改裝。

配備直噴式柴油發動機可以改裝為使用純植物油或廢植物油（用過的食用油）運行。然而，當在怠速或低負載下長時間運行時，某些類型的發動機可能會出現問題，因為植物油在這些條件下燃燒不佳。在寒冷天氣運行發動機時也會出現問題。即使是普通的柴油車在很冷的時候也難以啟動，植物油比柴油稠。車輛採用各種方法來加熱油，在寒冷氣候下使用的車輛可以增加額外的加熱器。一種類型的加熱器稱為“hot fox”，例如可以安裝在後備箱中；它會在油到達車輛前部之前對其進行加熱，在燃油到達噴油器之前，另一個加熱器會完成這項工作。

適當的發動機改造以及對燃料質量、環境溫度和運行方式的關注通常可以避免這些問題。

汽油發動機只能使用乙醇運行。但是，如果與酒精（乙醇或甲醇）混合，生物柴油也可用於汽油發動機^{[1] [需要驗證]}一些發動機、油類和環境條件可能會導致問題。

柴油機改裝

如上所述，純植物油只能與柴油機結合使用，即便如此，仍可能需要進行改裝才能使用這種油。這是當前使用直接噴射系統的結果（與可以在不修改植物油的情況下運行的間接噴射系統相反）。^[2]如果使用的發動機是汽油發動機，則只能將其轉換為使用（非常稀薄/優質）生物柴油或純乙醇運行。

植物油太稠，除非是熱的，否則無法在發動機中很好地燃燒。為了解決這個問題，一些車輛使用雙油箱系統：一個油箱用於石油柴油 - 或另一種起始燃料，即乙醇 - 另一個油箱用於植物油。發動機使用石油柴油（或其他啟動燃料）啟動並運行直至升溫，然後駕駛員切換到植​​物油箱。駕駛結束後，必須將車輛切換回石油柴油箱，以便將植物油從燃油管路中排出。如果不這樣做，汽車啟動時管路中仍然充滿植物油，啟動困難。也可以使用單油箱系統，該系統的優點是無需在車輛中攜帶石油柴油（或另一種起始燃料-即乙醇），從而減輕了重量並因此節省了燃料消耗。另一個優點是複雜性較低（減少了一個罐並消除了很多額外的管線）。不利的一面是發動機也沒有被加熱（由於 PPO 燃油管路中或附近的電加熱器，只有燃油被適當加熱）。另一個缺點是電加熱器不能直接從交流發電機供電（汽車電池必須始終存在於系統中）。

Oil that is not hot enough when it enters the engine will not burn properly and will cause buildup that will damage the engine.

Waste plant oil can also be used in a diesel engine. It must be filtered and water must be removed before it can be used as fuel, or it will damage the engine.

Plant oil extraction and conversion

The process of oil extraction is carried out the same way as for extraction of edible oil from plants. There are many crops grown in rural areas of the developing world which are suitable for oil production. Most of these have high energy contents; sunflower oil, for example, has an energy content of about 85% of that of diesel fuel.

There are two well-established technologies for oil extraction:

• The simple screw press, which is a device for physically extracting the oil from the plant - this technology is well suited to small-scale production of oil as fuel or as foodstuff in rural areas. The press can be motorised or hand-operated.
• Solvent extraction is a chemical process which requires large, sophisticated equipment. This method is more efficient - that is, it extracts a greater percentage of the oil from the plant - but is less suited to rural applications.

The oil, as well as being used for lighting and heating, can be used as a fuel in internal combustion engines.

Advantages and disadvantages

Biofuel is arelatively easy and cheap fuel. This, as the extraction of the fuel from the plants is easy and the fuel can also be stored for a long time^[3] without requiring complex or expensive storage methods.

Since waste plant oil (both WPO and PPO from crops intented for human consumption) is not produced in respond to an economic demand for fuel, using it is carbon neutral. Plant oils that are produced especially for use as a fuel (PPO from crops also useful for human consumption) are less ecological, yet are still closed-end recycled since the CO₂ that is emitted is sucked up by the next year's oil crops. In addition, crops that produce this PPO may still be more beneficial for the environment than were it not grown, depending on the location where the crop is grown and the vegetation that existed on this location.

The pollution from PPO is not as well studied as that of biodiesel, but it is thought to be similar to biodiesel -and much less than petrodiesel pollution-. The Danish Center for Plant Oil Technology has some interesting figures comparing rapeseed (Canola) oil and diesel fuel: 42% lower carbon monoxide, 63% lower unburned hydrocarbons, 19% lower nitrogen oxides, and 42% lower particulates. Cleaned WVO should have the same pollution charisteristics as PPO coming from the same crops.

Depending on the source of the oil, PPO and WPO it has more or less the same energy content as petrodiesel and more energy than biodiesel. This can be noticeable on under-powered vehicles.^[4]

See also

• Pure plant oil as fuel

References

• Tickell, J., Teickell, K., From the Fryer to the Fuel Tank: The Complete Guide to Using Vegetable Oil as an Alternative Fuel, Greenteach Publishing, 1999.
• Collection of fossil to biofuel conversion projects by BuilditSolar

External links

• DIY Diesel to veggie oil conversion e-books
• Several plans and info on vegoil conversions, site made by Dana Linscott
• Biogas and liquid biofuels (original)
• Making Biodiesel
• Wikipedia:Straight vegetable oil
• Pure plant oil fuel technology at the Open Biofuel Engine Development (OBED)wiki - Information about running vegetable oils in Diesel engines
• 10 steps to converting to wvo...the basic process
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