Eco-friendly hydraulic fluids are in demand for use on environmentally sensitive projects, such as work on nature reserves, as well as sub-sea applications. The requirement for a biodegradable fluid is often specified by the landowner or project owner, as they cannot risk a fluid leak contaminating the land and getting into the water systems in the area. There are biodegradable hydraulic fluids available on the market, and these typically use canola, sunflower or soybean oil as the base rather than the more traditional mineral oil. Under certain conditions these bio-based fluids achieve a similar performance to mineral oil based fluids, but these have not been tested extensively and for this reason it is recommended that the equipment be run at a 20% deficit compared to the usual pressure (so, at 80% of the maximum permissible operating load). As the use of biodegradable hydraulic fluids is usually determined by the project owners as a condition of the work being undertaken, there is no room for compromise here. Instead, the compromises must be made with the machinery and how it is set up. If time constraints are an issue as well as the eco-friendly credentials of the materials used, it is wise to select bigger and faster versions of the machinery that was intended to be used, as even running at 80% the job will get done in the same amount of time, as the intended equipment would at full capacity. There are also costs associated with the draining and flushing of unsuitable hydraulic fluid; some clients may insist on testing the fluid in the machinery to ensure it passes their tests for biodegradability. The oil itself is more expensive than the cheaper mineral oil based fluids, so the whole job becomes more expensive immediately biodegradable oils are used. Often, when a job has been priced without these considerations it becomes unprofitable unless the client is accommodating of over-runs due to the changes required in the machinery or the rental of bigger equipment. With time and the growing popularity of renewable energy and the general shift towards the use of more sustainable materials there will be developments in the production and testing of biodegradable hydraulic fluids. The costs associated with the purchase and use of bio-based fluids will come down, and the concerns around the maximum performance pressure will be assuaged, meaning that biodegradable hydraulic fluids will be able to compete at the same level as traditional mineral oil based ones.