| 7.         Other
Assets Other
assets consist of the following (in thousands).   
    |  |  | December
    31, |  |  
    |  |  | 2017 |  |  | 2016 |  |  
    |  |  |  |  |  |  |  |  
    | Alameda
    security deposit (1) |  | $ | 321 |  |  | $ | 597 |  |  
    | CD for Green Bank collateral
    security (2) |  |  | 1,019 |  |  |  | 1,012 |  |  
    | Nevada sales and use
    tax deposit |  |  | 49 |  |  |  | 49 |  |  
    | Facility Closure Trust
    deposit (3) |  |  | 450 |  |  |  | 100 |  |  
    | Various
    other assets |  |  | — |  |  |  | 147 |  |  
    |  |  |  | 1,839 |  |  |  | 1,905 |  |  
    | Less:  current
    portion (1) |  |  | (275 | ) |  |  | (275 | ) |  
    |  |  |  |  |  |  |  |  |  |  
    | Other
    assets, non-current |  | $ | 1,564 |  |  | $ | 1,630 |  |    
    |  | (1) | The lease deposit related to the Alameda headquarters
    is being released over time: $275,000 was released in June 2017 and $275,000 will be released in June 2018; the remainder
    will be released at the end of the lease term. The current portion is included in prepaid expenses and other current assets
    in the consolidated balance sheet. |    
    |  | (2) | The $1.0 million certificate of deposit is held
    by Green Bank as collateral for the Green Bank note payable balance. The deposit with Green Bank will be released after TRIC
    has three consecutive months of positive cash flow from operations. |    
    |  | (3) | The Company has entered into a Facility Closure
    Trust Agreement for the benefit of the Nevada Division of Conservation and Natural Resources (NDEP). Funds deposited in the
    Trust are to be available when and if needed, for closure and/or post-closure care of the facility related to potential decontamination
    and hazardous material cleanup. The Trustee will reimburse the Company or other persons as specified by the NDEP from the
    fund for closure and post-closure expenditures in such amounts as the NDEP shall direct in writing. In addition, the Trustee
    shall refund to the Company such amounts as the NDEP specifies in writing. $100,000 was deposited upon establishment of the
    Trust Fund, on October 31, 2016; $350,000 was deposited on October 31, 2017; and $220,000 will be due on October 31, 2018. |  |