Property, plant and equipment (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Property, plant and equipment
Property, plant and equipment, gross	$ 9,988,457		$ 9,988,457		$ 24,570,233
Less accumulated depreciation	1,487,214		1,487,214		1,722,379
Property, plant and equipment, net	8,501,243		8,501,243		22,847,854
Depreciation expense	646,465	499,812	1,667,619	1,265,049
Land and improvements
Property, plant and equipment
Property, plant and equipment, gross	699,308		699,308		3,049,765
Buildings and improvements
Property, plant and equipment
Property, plant and equipment, gross	6,357,967		6,357,967		19,788,447
Equipment
Property, plant and equipment
Property, plant and equipment, gross	2,920,561		2,920,561		1,306,597
Construction in progress
Property, plant and equipment
Property, plant and equipment, gross	$ 10,621		$ 10,621		$ 425,424