Indonesia yang merupakan negara kepulauan yang memiliki banyak wilayah perairan khususnya laut berpotensi untuk di jadikan sebagai media pembangkitlistrik dengan memanfaatkan tenaga gelombang laut. Kolom air osilasi (Osilatingwater colom (owc)) merupakan salah satu pembangkit listrik yang menggunakantenaga gelombang sebagai sumber energi. Keuntungan utama Osilating watercolunm dibandingkan kebanyakan konversi energi gelombang (wave energyconversi) lainnya adalah kesederhanaannya. Tempat di laksanakannya kegiatanpenelitian ini adalah labolatorium teknik mesin univeritas muhammadiyahsumatera  utara. Penelitian ini akan merancang 3 konsep alat konversi energy listrik tenaga gelombang dengan mengaplikasikan teknik kolom osilasi, memilih satu konsep dari tiga konsep yang di rancang,menganalisa kuat arus listrik yang di hasilkan alat konversi energi listrik tenaga gelombang dengan mengaplikasikan teknik kolom osilasi. Berdasarkan uji konsep pada rancangan alat pembangkit listrik tenaga gelombang teknik kolom osilasi konsep 3 yang memenuhi kreteria untuk di buat rancangan pembuatan karena pada konsep 3 kolom osilasinya mengerucut ke atas sehingga tekanan udara terpokus ke satu arah, setelah pengujian alat di dapat hasil dengan ketinggi air  30 cm, tinggi gelombang 1 cm dan panjang gelombang 66 cm menghasilkan listrik 0,06 v, dengan ketinggi air  40 cm, tinggi gelombang 5 cm dan panjang gelombang 75 cm menghasilkan listrik 0,08 v, dengan ketinggi air  45 cm, tinggi gelombang 6 cm dan panjang gelombang 97 cm menghasilkan listrik 0,06 v.

Fresh water from the desalination process is expected to be commercially produced in large quantities for world consumption needs. In this paper, experimental testing is carried out to obtain the overall characteristics of the desalination device to suit the placement of the test area. The single slope passive desalination tool model with a slope of 35o is still used as the object being tested because of its low cost and environmentally friendly use of solar energy. It is hoped that the performance improvement can be made after obtaining the characteristics of the desalination tool as a whole. It is obtained that the heat energy absorbed reaches 0.31 kWh with a solar intensity of 534.40 W/m2 at the same time. The production of fresh water during the test always follows the brightness and solar intensity. Experimentally obtained the allergy from the desalination device of 0.53 kW/m2 with an energy efficiency of 58.4% with the highest amount of hourly fresh water production of 2.6 kg.

At the Taqwa Muhammadiyah Mosque, a local place of worship, the power blackout is becoming very troublesome. On one side of the village where the research was conducted, the light intensity was high enough so that it is very good to be used as a source of renewable energy, namely solar panels or better known as PLTS. Method used in this research is experiment which is fully functional to control the implementation of the solar panel for electricity supply for the Mosque everyday activity Based on the results of measurements and calculations, the 200 Wp solar panel, when the weather is sunny, will be able to charge a battery by 68.2% or 87.2 Watts. In using the battery, the efficiency factor of the battery must be considered because it cannot be operated until all power is used up. Battery Capacity is 754.7 Ah and is able to supply DC lamps for 1 day and is able to supply AC loads for 1.02 day. So in 11 hours (lowest data) the 200WP solar panel is able to charge a battery with a capacity of 100Ah at 80% of the full battery capacity. Keywords: generator; PLTS; solar cell

This research was conducted in the underpass of the flyover in the Ampera Medan road corridor. The purpose and objective is to provide scientific concepts related to the spatial arrangement under flyovers that are not currently well managed and tend to cause acts of vandalism in the space. The construction of flying cross-construction in several plot areas is generally a new open open space linearly. underneath. Thus the space under the flyover which was initially unproductive will become a point of interest for the surrounding environment. Furthermore, a well-organized space and area will certainly generate economic growth through the support of a well-planned and correct management system. Based on a spatial analysis that is adapted to the function of public space, good planning and management is needed to support and maintain the continuity of activities through creativity and interesting information for the public in public spaces under the Ampera Medan railway flyover. The arrangement of open areas located in flyover and railway areas often creates contradictions and social problems that are quite crucial, especially related to state-owned land ownership. The open space under the Ampera Medan road overpass is currently a lost area (unproductive land) and an act of vandalism that contains immoral messages. The arrangement of open spaces located on the railway underpass as a public space will provide a positive image for the area and become an attractive place for the city of Medan with the availability of jogging tracks as a sports venue, performance arena and social interaction space for the community

Penerapan sistem refrigerasi pada sistem pendingin semakin ramai dibicarakan dan saat ini telah menjadi kebutuhan utama masyarakat. Klasifikasi dari penggunaan sistem pendingin bergantung dari kebutuhan sistem pendingin. Kebutuhan sistem pendingin berkaitan dengan beban pendingin yang mempengaruhi besar penggunaan energi listrik. Penelitian ini bertujuan untuk mengetahui pengaruh dari beban pendingin terhadap tegangan energi listrik pada sistem dan konsumsi jumlah arus yang terpakai. Perancangan sistem pendingin dalam bentuk lemari pembeku disesuaikan dengan kapasitas dari sumber energi listrik yang diperoleh dari panel surya 400 WP. Penggunaan pompa refrigerasi direncanakan berkapasitas 1/4 PK dengan tujuan peningkatan efisiensi penggunaan energi. Pengujian dilakukan dengan membandingkan data penggunaan listrik PLN dan listrik bersumber dari panel surya. Hasil menunjukkan bahwa temperatur box pendingin akan lebih cepat menurun jika menggunakan arus listrik PLN, hal ini dikarenakan arus listrik PLN selalu konstan ketika digunakan, berbeda halnya penggunaan listrik dari panel surya yang bergantung dengan perubahan cuaca. Tegangan arus listrik di awal waktu pengujian 27.3 Volt dan akan terus meningkat hingga puncaknya pada siang hari hingga mencapai 36.1 Volt. Koefisien kemampuan kerja mesin juga diuji, yaitu pada saat penggunaan arus listrik PLN nilai COP pada temperatur 25 o C hanya mencapai 2.23 sedangkan dengan menggunakan arus listrik dari panel surya mampu mencapai 2.46 dan bersamaan akan berangsur turun ketika mencapai temperatur 0 o C. Hal ini dikarenakan keuntungan penggunaan arus listrik yang bersumber dari energi matahari murah pada pencapaian yang sama.