کد: [انتخاب]
\documentclass{article}
\usepackage{multirow}
\begin{document}
\begin{table}
\centering
\caption{Your caption.}
\begin{tabular}{|l|l|l|l|}\hline
Wind&On shore&&$a_1$\\ \hline
\multirow{5}{*}{Solar}&\multirow{2}{*}{Photovoltaic}&On grid&$a_2$\\ \cline{3-4}
&&Off grid&$a_3$\\ \cline{2-4}
&\multirow{3}{*}{Solar Thermal}&Linear parabolic collector& $a_4$\\ \cline{3-4}
&&Central receivers (towers)&$a_5$\\ \cline{3-4}
&&Stirling dish (parabolic dishes)&$a_6$\\ \hline
\multicolumn{3}{|l|}{Geothermal}&$a_7$\\ \hline
\multicolumn{2}{|l|}{\multirow{6}{*}{Biomass}}&landfill gas&$a_8$\\ \cline{3-4}
\multicolumn{2}{|l|}{}&Muncipal Solid Waste (MSW)---incinerator&$a_9$\\ \cline{3-4}
\multicolumn{2}{|l|}{}&Muncipal Solid Waste (MSW)---digestion&$a_{10}$\\ \cline{3-4}
\multicolumn{2}{|l|}{}&Sewage (biosolids)&$a_{11}$\\ \cline{3-4}
\multicolumn{2}{|l|}{}&Animal Waste (manures)&$a_{12}$\\ \cline{3-4}
\multicolumn{2}{|l|}{}&Forest residues&$a_{13}$\\ \hline
\multicolumn{3}{|l|}{Fuel cell}&$a_{14}$\\ \hline
\end{tabular}
\end{table}
\end{document}