We have described the derivation of chemicals from petroleum and natural gas. But between 5 and 10% of organic chemicals come from other sources-coal, fats, oils, and carbohydrates. Historically, these sources are important because it was from them that the modern chemical industry evolved. Their present applications are also significant, particularly for specialty chemicals. Furthermore, because fats, oils, and carbohydrates are renewable resources, they represent an insurance policy for the future.
Coal, although a nonrenewable source of chemicals and energy, occurs on earth in much larger quantities than petroleum and will certainly outlast petroleum reserves by a few hundred years. The reserves to production ratio is six times that for oil and four times that for natural gas. Although seen as polluting and difficult to handle, it still accounts for a quarter of world and US energy consumption. In the European Union, this figure drops to 14.6% but in China it rises to more than 60%. We shall discuss it first, before we turn to the renewable sources.
Coal was important to the chemical industry in the nineteenth and early twentieth centuries. It provided carbide, and hence acetylene (Section 10.3), synthesis gas (Section 10.5), hence ammonia and methanol, petroleum-like fuels, and all the aromatic chemicals contained in coke oven distillate. This distillate still provides some chemicals, although the quantities (about 1.5%, see note at end of this chapter) pale by comparison with those from petrochemicals. The conversion of coal to synthesis gas (Section 10.4) was developed in the nineteenth century as a source of gaseous