The widespread use of conventional energy started during the industrial revolution with coal combustion and hydro power as main electricity sources, later followed by oil and nuclear power as main contributors of energy. For a long time, little was done to mitigate the well-known environmental risks associated with these energy sources. Recently, issues such as increased CO2 emissions put energy and environment higher on the political agenda and we are nowadays taking challenges in waste management, water, peak oil, peak phosphorous and pollution into consideration in energy systems development. Future energy systems will require intelligent technology (grid, market etc.) and new strategies to enable the introduction of different kinds of renewable energy sources and to make them available to the consumer. In future energy systems, both in urban and remote areas, many consumers will also be small scale producers of energy from solar, wind or biofuels.