West German Chancellor Helmut Schmidt, underlining Bonn's renewed interest in coal as the key to its future energy production needs, today announced a sizeable expansion of efforts to produce synthetic fuel and gas from this country's ample coal reserves.

The soaring price of oil, Schmidt said in a major statement on government energy policy before the parliament, has made these new techniques especially important.

Schmidt proposed no specific new energy-saving measures for West Germans, however, claiming that the general guidelines for voluntary conservation outlined in previous years and bolstered by such things as subsides for home insulation were still valid and could be increased. He avoided the politically explosive issue of asking for speed limits on West Germany's raceway-style autobahns, where powerful Mercedes and other vehicles drive at 100 or more miles an hour with impunity. He also defended Bonn's willingness to pay top prices for oil on the Rotterdam spot market.

The idea behind the synthetic fuel program, which involves expansion of a $65 million pilot plant begun in 1977 to a $350 million project through 1980, is to shorten the time it takes to make these processes competitive in the energy market.

Government specialists said that within a few years, oil and gas produced from coal might account for 1 to 3 percent of the imported oil now used here.

Ultimately, Schmidt said, economic growth and stabl employment levels would not be realizable without nuclear power.

But Bonn's nuclear future is cloudy and for the time being, Schmidt mad clear that coal was the "preferred" solution for production of electricity to fuel this country's highly industrialized society.

Although heavy use of coal pollutes the air and is expensive as a power generating source, costing the government more than $3 billion a year in subsidies, "it is the only important energy source with which we can make ourselves independent from foreign countries," Schmidt said.

Schmidt said oil-fired power stations account for only 9 percent of West Germany's electric power production, the lowest of any major industrialized country. When Bonn banned new oil-fired stations after the 1973 oil crisis, they were providing about 15 percent of West German electric power. In the 1980s, Schmidt said, West Germany plans to reduce such oil-fired plants to zero.

Bonn's strategy to achieve conservation is to keep raising prices, although West Germans, and Europeans in general, tend traditionally to be more energy-conscious than Americans. There is little air conditioning. Lights are turned off and thermostats turned down more regularly. Cars are more efficient -- although they are allowed to drive faster -- and public transportation is better.

West Germany is the only major Western country without highway speed limits and it is clear that oil imports could be reduced somewhat by such limits.

Schmidt, however, preferred not to confront the German love-affair with high-speed cars. Rather, he suggested that they leave the car at home more often and ease up on the gas pedal. If the international situation worsens or the voluntary appeal goes unheeded, he warned, "we will have to reconsider" the question of speed limits.

Gasoline here now costs about $2.20 a gallon and home heating oil costs have doubled in six months.

Both reflect what Schmidt acknowledged to be a very heavy West German dependence on the Rotterdm spot market. West Germany, he said, gets 20 percent of its gasoline and 40 percent of its heating oil there, paying top prices.

West Germany is Western Europe's largest oil consumer, imports all its oil and is the largest buyer on the spot market.

It has resisted joining efforts to control that market, where oil sells well above standard prices.

If West Germany tried to set price limits on its purchases in Rotterdam, Schmidt said, other countries would be willing to pay more and Bonn would wind up without the fuel it needs.