Energy hidden in plants

HIGH ECONOMIC VALUE: Jatropha curcas is cultivated on a large scale on China's Hainan Island for the production of biofuel (JIANG ENYU)

Experts estimate by the middle of the 21st century, various alternative biomass fuels produced by new technologies will account for 40 percent of total global energy consumption.

Many countries and regions in the world are studying "energy plants" or "oil plants" and setting up new bases of energy production. China is one of the first countries to take advantage of "energy plants."

The Chinese Government has formulated several policies to promote the development of the new sector. The first five-year plan on economic and social development of the new century proposed developing various oil substitutes and said liquid biofuels will be a key new industry for future development.

A forum on bioenergy was held in China on January 28, 2005, where the feasibility of producing liquid biofuels and biochemical products in the country was discussed. A month later, China passed its ground-breaking Renewable Energy Law.

Now China is able to design and build large-scale biopower plants independently and also to produce all the necessary equipment. China has also achieved breakthroughs in technologies on biofuel cells and optimizing biofuels. It has selected more than 300 strains of anaerobic bacteria for the development of biogas technology.

Since the 1980s, the Sichuan Academy of Forestry has been researching Jatropha curcas, a drought resistant plant, whose seeds can be used as material to produce biodiesel fuel, and studying its planting technologies and extraction techniques. The Chinese Academy of Sciences (CAS) has established a cultivation demonstration area for Jatropha curcas.

Scientists in central China's Hunan Province have completed studies on the production of methyl-ester fuel from Cornus wilsoniana fruit. China has also imported another tree for biofuel production, Euphorbia tirucalli, from South Africa, the United States and Brazil and studied its selection, cultivation, genetic improvement, processing technology and equipment.

In 2006, China's first garden of energy plants was established in the CAS's South China Botanical Garden, where major areas of studies include breeding high quality varieties having high energy storage rates. The garden uses Jatropha curcas as a research sample.

Although the production of biofuels started long ago, people couldn't make biodiesel out of Jatropha curcas until about 10 years ago. "It has wide adaptability to varied climate and soil, even the most barren land. The seeds have a germination rate of nearly 100 percent," said Wu Guojiang, a senior molecular biology research fellow from the CAS Garden. He said molecular biologists have successfully cloned several functional genes of the plant through DNA and ribonucleic acid extraction and established its regeneration and genetic transformation system, paving the way for turning the studies on Jatropha curcas into a model for research on other energy plants.

"Without using arable crop land, growing wild plants, such as Jatropha curcas, on marginalized land resources holds the key to the development of biomass energy in China," Wu said. There are vast barren mountains, hills and saline lands across the country, and if they are used to grow energy plants, it will save precious arable land, produce raw material for biofuel generation, improve the local ecology and provide local farmers with a new source of income.

The advantages to growing oil plants, Wu said, are the carbon dioxide produced by the combustion of biomass energies equals the amount the energy plants absorbed during their growth and the burning of biomass energy emits almost no sulfur dioxide. "This is an incomparable advantage over traditional fuels, such as gas, oil and coal."

The development of biomass energy still faces barriers of low energy conversion efficiency, high costs and insufficient raw materials, experts say, compared with the generation of wind and photovoltaic power.

The collection, storage, transportation and processing of biomass energy materials requires the input of large units of manpower, leading to high total costs of raw materials. Taking projects of using straw to generate electricity as an example, given the cost of transportation and manpower during the purchase of straw, it is better to collect straw from within only a radius of less than 50 km to recover costs. Biofuel projects using woody plant materials as sources can be even more expensive, considering the cost of the cultivation of trees, orchard planting and maintenance, fruit collection and transportation.

The key to overcoming these hindrances and fostering the new sector, experts say, is to promote scientific research.