The Rise and Rise of Green Chemistry

Agriculture is worth more than €5 billion to the Irish economy each year, but the chemistry involved in modern agriculture can also have a high environmental cost. To take just two examples:

  • There are 1.5 billion cows in the world, producing 18% of the planet’s greenhouse gases, particularly carbon dioxide (CO2) and methane (CH4) – even more than cars.
  • Another issue is ‘eutrophication’, where fertilisers derived from phosphorous and nitrogen wash into lakes, streams, rivers and oceans. It causes algal blooms which destroy sea life and can poison the local environment.

But it’s not all doom and gloom. Advances in agricultural chemistry are allowing us to farm in a more environmentally sensitive way.

Algal blooms on Dianchi Lake in China

Algal blooms on Dianchi Lake in China (Image: Eutrophication & Hypoxia)

Biopesticides

Biopesticides are naturally occurring substances and organisms that control pests and fungi and stop them from destroying our crops. These are different from man-made pesticides which chemically kill destructive pests.

Not only do biopesticides boost and protect plant life, they’re generally a lot kinder to the environment and over time can enable damaged ecosystems to recover.

An example of these biopesticides is chitin (in chemical terms it is a long-chain polymer, a derivative of glucose). It can be found inside the shells of shrimps and other crustaceans and it works by improving a plant’s ability to defend itself against pests. It also boosts photosynthesis, so plants grow larger and faster.

An oil rig at sunset

An oil rig at sunset (Image: US National Archive)

Green Chemical Cars

Heard of biofuels? This is probably green chemistry’s biggest project. With oil set to disappear as a major resource in a few decades, the race is on to discover other means of fuelling vehicles.

One alternative is solar power, but thanks to bioethanol chemistry seems to be beating physics to it. Ethanol is a pure form of alcohol that is already powering cars. It comes from fermenting common crops such as sugar cane and potatoes and even marine organisms such as algae. This means it is renewable and clean.

An average car can use a mix of ethanol (up to 15%) and petrol to reduce emissions and dependence on fossil fuels. Many car companies are developing cars that can run entirely on ethanol. The Irish Government aims to have 10% of transport running on renewable fuels by 2020.
View an animated feature on how ethanol is made »

Clean, Green Headaches

Another example of green chemistry is how the pharmaceutical industry produces one of the most commonly used medicines in the world: Ibuprofen. Its more common trade names include Neurofen and Advil, and it is used to ease many sorts of pain, from colds and flu to arthritis.

Previously, the synthesis (or production) of Ibuprofen involved six chemical steps, and just 40% of the atoms involved in the process were used (i.e. 60% went to waste). Now this process can now be done in just three steps by using solid catalysts (in this case, Raney nickel). It also uses atoms far more efficiently – 80% are used, with just 20% going to waste.

Ibuprofen is now a far more efficient process thanks to Raney nickel

Ibuprofen is now a far more efficient process thanks to Raney nickel (Image: Quite Peculiar)