Giving money for kafaarat yameen or kafaarat al-zihar (expiation for divorcing one’s wife by zihaar, which is a jaahili form of divorce in which the husband says to his wife, “You are to me as my mother’s back”) or for breaking one’s fast in Ramadaan by having intercourse, instead of giving food, is not sufficient, even if one thinks that money is more useful. Rather the person has to give food of the type that he gives to his own family, whether it be wheat, dates, barley, rice or whatever, because this expiation is an act of worship that must be done in the manner enjoined by sharee’ah. There are many poor people who will accept this food. The person who is obliged to offer expiation does not have to distribute this food all at the same time, rather he may do it in the way that is easiest for him. 

From Fataawa al-Lajnah al-Daa’imah, 23/8 

If a person cannot find ten poor people, or it is difficult for him to give the expiation himself, then some charities can give the kafaarah on behalf of people and give it to those who are entitled to it. 

So he could pay the equivalent amount to a trustworthy charity to distribute the kafaarah on his behalf. 

And Allaah knows best.