One protester was charged with disorderly conduct for defying deputies' orders for him to remove a mask, sheriff's spokeswoman Teri Barbera said.
Deputies also charged 20 other men and six women with unlawful assembly and trespassing after they were warned to leave the entrance to Palm Beach Aggregates off State Road 80 near 20-mile Bend.
One person was treated for heat exhaustion, Barbera said.
Barbera noted that about 10 protestors had linked themselves in a circle and had slipped their arms through metal tubes to keep authorities from separating them. They were ultimately freed from the contraption and arrested, she said.
It was not immediately clear why the demonstrators chose that location for a protest. The demonstrators were speaking against the West County Energy Center, a natural-gas powered plant that is expected to produce power for about 750,000 homes throughout Palm Beach County when it is completed in 2012.
Critics have said the plant will spur needless growth in western Palm Beach County and that it will pump more pollutants into the atmosphere.