Note 4 - Property and Equipment (Tables)
 12 Months Ended
Dec. 31, 2019
Notes Tables  
Property, Plant and Equipment [Table Text Block]
   
December 31, 2019
    
December 31, 2018
  
                 
Machinery and equipment
   $
36
     $
1,367
  
Computers and other
    
88
      
7,540
  
Aquifer
    
-
      
482
  
Leasehold improvements
    
-
      
1,553
  
     
124
      
10,942
  
Accumulated depreciation and amortization
    
(52
 )    
(9,825
 )
                 
    $
72
     $
1,117