There is a limit for generating static images without api key, so make sure you wait a bit when getting forbidden error from Google request.

public static string rootPath = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
        public static string csvPath = rootPath + "\\Addresses.csv";
        public static Random rnd = new Random();
 
        public static void Main()
        {
            using (var sr = new StreamReader(csvPath))
            {
                while (!sr.EndOfStream)
                {
                    var data = sr.ReadLine().Split('|');
                    var address = data[0];
                    var postCode = data[1];
 
                    SaveFile(address, postCode);
                }
            }
 
            Console.WriteLine("done!");
            Console.ReadLine();
        }
 
        public static void SaveFile(string address, string postCode)
        {
            try
            {
                var filePath = new DirectoryInfo(rootPath).Parent.Parent.Parent.FullName + @"\output\" + postCode + ".jpg";
                if (File.Exists(filePath))
                {
                    Console.WriteLine("skipped " + address + " " + postCode + " (image exists in output directory)"); return;
                }
 
                Console.WriteLine("processing " + address + " " + postCode);
 
                using (var wc = new WebClient())
                {
                    var url = "https://maps.google.com/maps/api/staticmap?address=" + address + "&center=" + postCode + "&size=275x275&format=jpg&maptype=roadmap&zoom=15.5&markers=color:0xE21A9B|label:T|" + postCode + "&sensor=false";
                    wc.DownloadFile(url, new DirectoryInfo(rootPath).Parent.Parent.Parent.FullName + @"\output\" + postCode + ".jpg");
                }
 
                Thread.Sleep(rnd.Next(300, 2300)); //wait a bit
            }
            catch (Exception ex)
            {
                Console.WriteLine("error for: " + address + " | " + postCode + Environment.NewLine + ex.Message);
            }
        }
    }

Download project: googleImageApi

Artykuł Generating static map images using Google Map API pochodzi z serwisu Proxmedia.