Does training require GPU?

Since it use torch.CudaTensor, so it require GPU, right?
Is there any way I can train it only using CPU?

BTW, here is my command line for training
th train.lua -learning_rate 0.003 -data_json data/training_data/training_json -data_h5 data/training_data/training_h5 -gpu -1 -checkpoint_path data/training/cp.v1 -id densecapv1 -backend 'nn'

And here is the error I got.
/usr/local/google/home/wangyu/torch/install/bin/luajit: ...gle/home/wangyu/.luarocks/share/lua/5.1/torch/Tensor.lua:238: attempt to index a nil value
stack traceback:
...gle/home/wangyu/.luarocks/share/lua/5.1/torch/Tensor.lua:238: in function 'type'
.../google/home/wangyu/.luarocks/share/lua/5.1/nn/utils.lua:52: in function 'recursiveType'
...google/home/wangyu/.luarocks/share/lua/5.1/nn/Module.lua:126: in function 'type'
.../google/home/wangyu/.luarocks/share/lua/5.1/nn/utils.lua:45: in function 'recursiveType'
...google/home/wangyu/.luarocks/share/lua/5.1/nn/Module.lua:126: in function 'type'
train.lua:48: in main chunk
[C]: in function 'dofile'
...ngyu/torch/install/lib/luarocks/rocks/trepl/scm-1/bin/th:145: in main chunk
[C]: at 0x00406670