ENERGY USE EFFICIENCY IN BIOMASS PRODUCTION SYSTEMS - Economics of Sustainable Energy in Agriculture - page 79

efficiency are required. Knowledge obtained in studies on other sustainable
energy sources might be of use and variables such as payback-time or solar
energy use efficiency can be incorporated.
4.4 Shift towards low-input agriculture and the
consequences for energy crops
Up to now, the choice of a high-input versus a low-input system has only
been evaluated in the context of its energy yield/ efficiency. It has been
concluded that the high-input systems result in the highest energy yields. In
reality, the choice of a high or low-input system is also determined by
socio-economic factors. The cost-effectiveness of the system plays a role,
as well as the social acceptance of production systems. High-input biomass
production systems can be expected to have the same effects on the
landscape and environment as high-input agricultural systems. In European
agriculture, a shift from high-input to organic farming is observed. Based
on this information, the future feasibility of large-scale high-input energy
crop farming will be low. The expected shift from high-input to low-input
(or organic) production systems will have a major impact on the potential
of biomass as an energy source. On one hand, the low-input food
production systems will require more land for the production of food,
implying a reduction of the land available for energy production. Secondly,
energy yields that can be obtained from these areas will be lower, since it is
not likely that future production will come from high-input systems.
5. CONCLUSION
Fossil energy use efficiency is higher in low-input crop production systems
than in high-input systems. This is caused by the fact that in low-input
systems, a relatively large amount of the used nitrogen originates from
non-fossil resources. In energy crop production systems, solar energy is
converted into plant material (with the aid of fossil energy). The net
(output-input) energy yield of high-input systems is much higher than the
net yield from the low-input systems. The choice of a particular production
system will thus have significant consequences for the energy yields that
can be obtained.
REFERENCES
Conforti, P, and M. Giampietro (1997) Fossil energy use in agriculture: an international
comparison. Agriculture, Ecosystems and Environment 65, 231 -243.