Discontinued operations - Mexico project development (Details) - USD ($)	Jun. 30, 2023	Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total assets of discontinued operations	$ 21,449,715	$ 21,660,768
Value added tax, net of allowance	1,940,725	1,711,234
Discontinued Operations. | Mexico Project Development
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Cash	211,272	442,252
Accounts receivable	12,675	12,675
Prepaid expenses and other current assets	95,489	75,826
Value added taxes receivable (net of allowance of $1,940,725 and $1,711,234, respectively)	991	727
Land	21,126,898	21,126,898
Other assets	2,390	2,390
Total assets of discontinued operations	21,449,715	21,660,768
Total liabilities of discontinued operations	$ 280,695	$ 389,884