Revenue (Tables)

9 Months Ended

Sep. 30, 2023

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The following table provides information about disaggregated revenue:

	Three Months Ended				Nine Months Ended
	September 30,				September 30,
$ in thousands	2023		2022		2023		2022
Project revenue	$	950	$	1,324	$	2,401	$	4,207
Engineering services revenue	146		43		473		168
Total services revenue	1,096		1,367		2,874		4,375
Grant revenue	1,177		1,733		2,730		4,656
Total revenue	$	2,273	$	3,100	$	5,604	$	9,031

Schedule of Accounts, Notes, Loans and Financing Receivable

Receivables, net consisted of the following:

$ in thousands	September 30, 2023		December 31, 2022
Trade receivables	$	866	$	1,119
Grant receivables:
Billed	1,421		—
Unbilled	2,791		5,610
Other grant receivables	—		1,578
Total grant receivables	4,212		7,188
Contract assets	—		560
Other receivables	391		328
Total receivables	5,469		9,195
Allowance for doubtful accounts	(198)		—
Total receivables, net	$	5,271	$	9,195

Contract with Customer, Contract Asset, Contract Liability, and Receivable

The following table outlines the activity related to contract assets, which is included in total receivables on our consolidated balance sheets:

$ in thousands
Balance as of December 31, 2022	$	560
Additions to unbilled receivables	177
Amounts billed to customers	(729)
Foreign currency translation adjustments	(8)
Balance as of September 30, 2023	$	—

The following table outlines the activity related to contract liabilities:

$ in thousands
Balance as of December 31, 2022	$	10,348
Payments received in advance of performance	5,460
Revenue recognized	(2,401)
Recognition of consideration payable associated with Project Warrants	(234)
Other	(3)
Balance as of September 30, 2023	$	13,170