Magento - Add textarea to admin system config tables

Data.php

<?php
/**
 * Use
 */
class Module_Adminhtml_Block_Config_Data extends Mage_Adminhtml_Block_System_Config_Form_Field_Array_Abstract
{
    protected $_textareaRenderer;

    public function __construct()
    {
        $this->setTemplate('system/config/form/field/array.phtml');
        parent::__construct();
    }

    public function _prepareToRender()
    {
        $this->addColumn('textarea', array(
            'label' => $this->__('Textarea'),
            'renderer' => $this->_getTextareaRenderer()
        ));

        $this->_addAfter = false;
        $this->_addButtonLabel = $this->__('Add');
    }

    protected function  _getTextareaRenderer()
    {
        if (!$this->_textareaRenderer) {
            $this->_textareaRenderer = $this->getLayout()->createBlock(
                'module_adminhtml/system_config_form_field_textarea', ''
            );
        }
        return $this->_textareaRenderer;
    }
}

Textarea.php

<?php
class Module_Adminhtml_Block_System_Config_Form_Field_Textarea extends Mage_Core_Block_Template
{
    public function _toHtml()
    {
        $inputName = $this->getInputName();
        $columnName = $this->getColumnName();
        $column = $this->getColumn();

        return '<textarea type="text" name="' . $inputName . '" value="#{' . $columnName . '}" ' .
            ($column['size'] ? 'size="' . $column['size'] . '"' : '') . ' class="' .
            (isset($column['class']) ? $column['class'] : 'input-text') . '"'.
            (isset($column['style']) ? ' style="'.$column['style'] . '"' : '') . '>#{' . $columnName . '}</textarea>';
    }
}