## Cost of transport The total cost for transport

2.3.5. Transport capacity restriction

Eqs. (28) and (29) represent that BAMB-4 the total amount of the grain/biofuel transported by one kind of transport model cannot exceed its capacity.equation(28)∑i=1I∑k=1Ktikj1?Dj1u,j1=1,2,…,J1equation(29)∑i=1I∑k=1Ktikj2?Dj2u,j1=1,2,…,J2

2.3.6. Production capacity restriction

Eq. (30)represents that the amount of biofuel production should be bigger than the lower bound of production capacity, and smaller than the upper bound of production capacity.equation(30)PCkl?∑i=1IDik×rk?PCku,k=1,2,…,K

2.3.7. Mass balance

Eq. (31)means that the sum of grain distributed from an agriculture zone to the factories by different transport models equals the total amount of grain distributed from the agriculture zone to those factories. Similarly, Eq. (32)means angina the sum of biofuel distributed from a factory to a market center by different transport models equals the total amount of biofuel distributed from the factory to those market centers. Eq. (33)expresses the mass balance between grain and biofuel.equation(31)∑j1=1J1tikj1?∑k=1KDik,i=1,2,…,Iequation(32)∑j2=1J2tklj2?∑l=1LDkl,k=1,2,…,Kequation(33)∑i=1IDik×rk=∑l=1LDkl,k=1,2,…,K