The reduction of costs at a national level for countries that import fossil fuels is also of value, especially in light of recent price increases and global unrest. There is considerable controversy over whether currently available biofuels (typically derived from grain or oil seed crops) are produced sustainably at this time, whether they provide much net C02 reductions, and whether they may have adverse impacts on food security and agricultural markets. The answers depend on each situation, but current biofuels do not now provide significant net benefits. There are exceptions such as sugar cane ethanol in Brazil, where at least the costs are low and C02 emissions reductions appear to be substantial.