library(sf)
library(tidyverse)

load("wind_test.rda")

buffer  <- wind.test %>% select(ID) %>%
  st_buffer(dist=1000) %>%
  st_union() %>%
  st_cast("POLYGON") %>%
  st_sf() %>%
  mutate(turbines = st_intersects(buffer, wind.test) %>% map_int(length))