 Historically, tax-exempt bonds were used to underwrite investments in public goods and services and, for this reason, SEBs are seen as a critical tool for SEUs to serve their communities.An SEU can be given bond issuing capacity which allows it to sell tax-exempt bonds in order to treat sustainable energy as an infrastructure scale investment.In 2011, the Delaware SEU issued a statewide tax exempt bond for SEUs, the first of its kind in the U.S., acquiring $72.5 million for capital investments in sustainable energy measures.