try to send your post data as a query string
$str = '';
foreach($data as $key => $val){
$str.= $key.'='.$val.'&';
}
rtrim($str,'&');
curl_setopt($ch, CURLOPT_POSTFIELDS, $str);
or
curl_setopt($ch, CURLOPT_POSTFIELDS, 'address='.$_POST['address']);
or
curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($data));
According comment error you need code:-
<?php
$address = "Capitol Avenue, Elsmere, Kentucky";
$address = str_replace(" ", "+", $address);
$address_url = "https://maps.googleapis.com/maps/api/geocode/json";
$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, $address_url.'?address='.$address);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 0);
echo $response = curl_exec($ch);
print_r(curl_getinfo($ch));
curl_close($ch);
$response_a = json_decode($response); ?>
?address=ADDRESS_HERE&fields..) -http_build_query()