Stockholders' Equity - Share-Based Compensation (Detail) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	$ 112,169	$ 189,155
Cost of product sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	5,466	8,483
Research and development
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	22,484	35,847
Selling, general and administrative
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	84,219	144,825
Fuel Storage & Vehicle Systems
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	31,651	48,867
Fuel Storage & Vehicle Systems | Cost of product sales
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	5,466	8,483
Fuel Storage & Vehicle Systems | Research and development
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	22,484	35,847
Fuel Storage & Vehicle Systems | Selling, general and administrative
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	3,701	4,537
Corporate
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	80,518	140,288
Corporate | Selling, general and administrative
Compensation Related Costs Share Based Payments Disclosure [Line Items]
Share-based Compensation Expense	$ 80,518	$ 140,288