Increase the X length of a tikzpicture

Question

This is the code that i'm using (Thanks to percusse in here):

\documentclass[conference]{IEEEtran}
\usepackage{lipsum} %<-- For dummy text
\usepackage{pgfplots}
\pgfplotsset{compat=1.7}


\newcounter{groupcount}
\pgfplotsset{
    draw group line/.style n args={5}{
        after end axis/.append code={
            \setcounter{groupcount}{0}
            \pgfplotstableforeachcolumnelement{#1}\of\datatable\as\cell{%
                \def\temp{#2}
                \ifx\temp\cell
                    \ifnum\thegroupcount=0
                        \stepcounter{groupcount}
                        \pgfplotstablegetelem{\pgfplotstablerow}{[index]0}\of\datatable
                        \coordinate [yshift=#4] (startgroup) at (axis cs:\pgfplotsretval,0);
                    \else
                        \pgfplotstablegetelem{\pgfplotstablerow}{[index]0}\of\datatable
                        \coordinate [yshift=#4] (endgroup) at (axis cs:\pgfplotsretval,0);
                    \fi
                \else
                    \ifnum\thegroupcount=1
                        \setcounter{groupcount}{0}
                        \draw [
                            shorten >=-#5,
                            shorten <=-#5
                        ] (startgroup) -- node [anchor=north] {#3} (endgroup);
                    \fi
                \fi
            }
            \ifnum\thegroupcount=1
                        \setcounter{groupcount}{0}
                        \draw [
                            shorten >=-#5,
                            shorten <=-#5
                        ] (startgroup) -- node [anchor=north] {#3} (endgroup);
            \fi
        }
    }
}
\pgfplotstableread{
%Res. Number    Res A.  Res.B   Group
1               0.5     4.224   1
2               0.6     4.124   1
3               0.7     4.067   1
4               0.8     4.88    1
5               0.9     4.391   1
6               1       4.273   1
7               1.1     5.506   2
8               1.2     5.391   2
9               1.3     5.52    2
10              1.4     5.418   2
11              1.5     5.285   2
12              1.6     5.194   2
13              0.5     6.224   3
14              0.6     6.124   3
15              .7      6.067   3
16              0.8     6.88    3
17              0.9     6.391   3
18              1       6.273   3
19              1.1     8.506   4
20              1.2     8.391   4
21              1.3     8.52    4
22              1.4     8.418   4
23              1.5     8.285   4
24              1.6     8.194   4
}\sindezoito

\title{Some article title}

\author{The Author}

\begin{document}
\maketitle
\begin{abstract}
\lipsum[2]
\end{abstract}
\lipsum[1-6]


\begin{figure*}\centering
\begin{tikzpicture}
\begin{axis}[ybar stacked, compat=newest, %Better label placement
enlarge y limits=false,
ymin=0,
enlarge x limits = .1,
bar width=12pt,
legend style={at={(0.5,-0.15)},anchor=north,legend columns=0},
x tick label style={rotate=45,anchor=east},
ylabel={Power $(mW)$},
xtick=data,
nodes near coords=\rotatebox{90}{\pgfmathprintnumber\pgfplotspointmeta},
axis lines*=left,
y axis line style={opacity=0},
yticklabels={\empty},
ytick style={draw=none},
cycle list={
    {fill=black!60,draw=black!60},
    {fill=black!40,draw=black!40},
    {fill=black!20,draw=black!20}
},
axis on top,
major grid style=white,
ymajorgrids,
xticklabels =   {BS,BS-A,HP,HP-A,LP,LP-A,BP,BP-A,HP,HP-A,LP,LP-A,
                 BS,BS-A,HP,HP-A,LP,LP-A,BP,BP-A,HP,HP-A,LP,LP-A},
legend style={
      font=\footnotesize,
      cells={anchor=west},
      legend columns=5,
      at={(0.5,-0.2)},
      anchor=north,
      /tikz/every even column/.append style={column sep=0.2cm}
    },    
%           draw group line={[index]3}{1}{30c - 180}{-3.5ex}{7pt},
%        draw group line={[index]3}{2}{50c - 180}{-3.5ex}{7pt},
%        draw group line={[index]3}{1}{30c - 350}{-3.5ex}{7pt},
%        draw group line={[index]3}{2}{50c - 350}{-3.5ex}{7pt},           
    ]


\addplot table[x index=0,y index=1] \sindezoito;
\addplot table[x index=0,y index=2] \sindezoito;
\legend{Switching, Internal Cell}
\end{axis}
\end{tikzpicture}
\caption{Power results examples forum.}
\label{fig:0.18.sin}
\end{figure*}

\lipsum[1-6]
\end{document}

I'd like to plot this with an increased 'x length' in the page, as you may see the plot stays in small square at the center of the page, and it has lot of bars, they estay too next one another. How may i increase that area plot to present the data in a better way?