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Native plants smart choice for biofuels

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Technology

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Biofuels made from native plants could be the most environmentally and economically favourable option, researchers say.

Credit: Wikimedia

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Native perennial plants could be used to make biofuels that are not only more environmentally sustainable, but more economically attractive to boot.

Using a mixture of local plants as fuel appears to reduce greenhouse gas emissions and improve local water quality and biodiversity, according to US researchers at the Joint Global Change Research Institute in Maryland.

The team, led by Cesar Izaurralde, is using field trials and computer simulations to examine the economic and environmental potential of 'cellulosic' biofuels, which are made from woody or herbaceous plants, instead of starch-based biofuels from corn or sugar cane.

"The most important part of our work is the comprehensive research approach we are using," said Izaurralde.

The team is trying to find which crops grow best under the normal conditions of the test area, the prairies of America’s Great Lakes region.

Plants that thrive on the natural rainfall, temperatures and soil of the region need less care, so less greenhouse gas is emitted while raising them, and they cost less to cultivate, the researchers have found.

Izaurralde’s team also wants to find biofuel crops that don’t interfere with or replace food production, thereby driving up food prices, as this has been a major point of biofuel criticism in the past.

Instead, the researchers suggest, with the right kind of plants, biofuels could be produced on marginal cropland – farmland that has been degraded and is no longer suitable for food production.

A mixture of native prairie plants is a good choice for biofuel crops in the Great Lakes region, Izaurralde said, because they are already adapted to the conditions, improve biodiversity and can be grown on the desired marginal agricultural land.

Furthermore, Izaurralde points to a paper that appeared in the US journal Science last year, showing that biofuel from the perennial plants is actually carbon negative, because the amount of carbon absorbed by the growing plants exceeds the amount released from fossil fuels used in growing and processing the crops.

In theory, biofuels are good for the environment because they only recirculate carbon already in the atmosphere.

But when rainforests or grasslands are felled and ploughed for conversion to biofuel cropland, huge amounts of carbon sequestered in the soil are released, and fertilising the crops with petroleum-based chemicals also adds to their carbon footprint.

Those problems are avoided by planting the hardy prairie grass on already available, degraded land.

Choosing perennials that don’t need to be replanted annually further reduces the amount of greenhouse gases released in biofuel production.

Another bonus of using local species is an increase in biodiversity in the area, because the grasses provide more habitat for predatory insects that help control pests, bees that pollinate crops, and local bird species.

Deborah O’Connell, a researcher at Australia’s CSIRO Sustainable Ecosystems in Canberra, said that using local plants is also a smart choice because of the weed potential of many conventional biofuel crops.

"The perfect energy crop is also the perfect weed," she said.

Australian researchers are testing a range of cellulosic biofuel crops, O’Connell said, including trees like the oil mallee, which is planted through wheat fields in Western Australia to prevent salinity and provide electricity-generating feedstock, charcoal for water filtration and eucalyptus oil.