(9 litres) per (100 kilometres) = 9.0 × 10-8 m2
More about calculator.

I'd imagine with an abundance of free energy

The WHO said in support of the 2003 0.5mg/L guildeline and repeated in the 2009 guideline “Short and long term oral exposures to boric acid or borax in laboratory animals have demonstrated that the male reproductive tract is a consistent target of toxicity. Testicular lesions have been observed in rats, mice and dogs given boric acid or boric in food or drinking water. Development toxicity has been demonstrated experimentally in rats, mice and rabbits”.

But the reasons for this decision which were promised in 2010 have still not been published on the WHO website. Ditto the Australian guidelines that allow 67% higher boron guidelines than established by the WHO.

There is an inverse relationship between boron toxicity and weight. The WHO used an average adult weight of 60kg and Australia used 70kg—why? But even if the new guidelines are safe for adults, especially obese adults, it does not follow that they are safe for children, foetuses, small animals and plants. The UN Food and Agricultural Organisation produced a list of 58 major food crop varieties which show that only nine would live with total boron levels above 4mg/L based on field research in 1960, 1973 and 1982.

Sea water is difficult to desalinate to make potable water using filters. All sea water contains boron, mostly as boric acid. The boric acid molecule is about the same size as a water molecule.
Boron occurs in the sea at a concentration of at least 4 milligrams per litre or over 20 times a safe drinking level of 0.2mg/L where it is safe for all mammals and plants. Tests in the US show that boron in dam water is 0.047 mg/L on average. Boron is tasteless. Membranes used to filter sea water under pressure are not efficient at reducing boron and their ability to remove boron diminishes with use.

Even in order to get the boron level down to 0.5mg/L (twice the safe level for all mammals) will require the RO filters to be changed every six months an increase of 12% in the operating cost. Usually RO plants are small and are used for short periods to produce permeate (or manufactured water) for use on installations like oil rigs or mixed with fresh water to dilute boron to safe levels.

From 2003 to 2009 0.5mg/L of boron was considered to be a safe level for drinking and is the maximum boron amount specified in the Wonthaggi contract. Records from Australia’s Gold Coast and Kurnell plants show that boron has not been kept at levels below 0.5mg/L and the level exceeds 0.5mg/L after about six months. The Kurnell plant which is currently up for sale by the NSW government is mixed with water held in the large Warragamba Dam to dilute the boron to safe levels, apart from the suburbs of Prospect, Ryde and Potts Hill which receive unmixed water for pressure reasons.

The toxicity tests entailed feeding a group of pregnant rats increasing amounts of boric acid to the point where the average foetal weight loss was 5% compared to a control group. The World Health Organisation then used this standard formula to establish safety guidelines for humans based on water consumption, boron retention and adult body weight. On this basis the WHO set the 0.5mg/L safety guideline which was adopted by Australia.
It was only when reverse osmosis plants began to replace distillation plants that the WHO guidelines became of more than academic interest to the water industry. In 2008 the Harvard Medical School undertook an exhaustive survey of boron literature which concluded that additional boron exposure above the background level in drinking water should be avoided by children under 18 years of age.

The original boron safety standard of 0.5mg/L is costly to meet. One way of reducing that cost is to relax the guidelines.

Despite the lack of new laboratory or population research in 2009 the WHO increased the safety guideline to 2.4mg/L and the Australian guidelines were increased to 4mg/L in 2004 just before Australia’s first large desalination plant was approved. The 400% increase in the WHO guidelines and the 800% increase in the guidelines for Australia are not based on published toxicology or epidemiology. This apparent regulatory capture has international as well as national implications for the development of public health standards.

the keyword here is salinification.

what do you do with the brine?